PhD programmes

Completed doctoral research projects

Method for improving the maneuverability of a top-wing monoplane.
This dissertation is based on experimental work and describes a method for improving the maneuverability of trainer aircraft built in accordance with the classical laws of aerodynamics.

The appearance of highly maneuverable fighter aircraft automatically, so to speak, increased the requirements for aircraft designed for pilot training.

This paper presents the method for and way of achieving a planned effect consisting in an increase in the maneuverability of a modernized trainer aircraft built in accordance with the classical aerodynamics laws by means of introducing modifications worked out during an aerodynamic design process carried out with the use of wind tunnels operated by the Aviation Institute. The obtained results of model testing in wind tunnels and comparison thereof with data from tests flights conducted with the use of prototype aircraft provided evidence justifying the statement contained in the thesis according to which higher maneuverability (better aerodynamic characteristics) of a top-wing monoplane trainer aircraft built in accordance with classical aerodynamics laws can be achieved by means of equipping its wing with high-lift devices and strakes (strake, LEX) installed at the wing root.

In order to increase lift generated by the wing within the whole range of operational velocities of the aircraft and to raise the limit above which wing buffeting occurs, the author has proposed to introduce strakes (generators of vortex flow on the upper surface of the wing near the fuselage, within the symmetrical profile area, installed at the wing root).

In order to increase the lift generated by the wing at low speeds and to decrease the angle of airflow deflection behind the wing, the author has proposed introduction of high-lift devices (on the leading and trailing edges) based on the Fowler flap that generates lift not only by means of airflow deflection but also by increasing the wing area (broadening), which, as a consequence, prevented airflow separation on the bottom source of the horizontal stabilizers.

Modifications worked out by the author as options were subsequently introduced during the model completion and subjected to tests in wind tunnels.

The necessary corrections were introduced successively, depending on the achieved test results.

Introduction of prototype modifications was planned and effected in two phases.

Phase one: an I-22 ”Iryda” aircraft prototype was modified by means of installing strakes and increasing the height of the vertical stabilizer.

Phase two: another aircraft was reconstructed and provided additionally with wholly changed high-lift devices comprising double-segment slats on the leading edge and Fowler flaps.

The analyses and surveys presented in the paper have enabled positive verification of the thesis proposed in the dissertation.

The developed method for selecting components (strake, high-lift devices) and testing made it possible to provide the modernized aircraft with increased maneuverability capabilities.

The subject of this doctoral dissertation focuses on the influence of gyroscopic effects on dynamic properties of light turboprop aircraft. Gyroscopic moments are generated by the turbopropeller power units and cause coupling between longitudinal and lateral dynamics.

The main purpose of this study was to investigate the influence of the gyroscopic effects on the dynamic stability and the response of aircraft to manoeuvres following either a rapid deflection of the control surfaces or wind gust.

As a representative of the General Aviation aircraft, for which calculations were carried out, a Polish turboprop aircraft I-31T was selected. The analyses were conducted for several different mathematical models of aircraft motion, which allowed to investigate the relationship between introduced simplifying assumptions and the aircraft response, including non-linear terms in equations of motion expressing the influence of inertial coupling.

There was carried out an analysis of the sensitivity of dynamic stability versus dimensionless aerodynamic derivatives, received from different data sources. The analytical and experimental methods (measurements in the wind tunnel for the scaled model and flight test of the I23 prototype aircraft) were employed.

The results of numerical simulations were compared to the aircraft flight tests. There were also evaluated compliance of the dynamic characteristics obtained by the use of different computational packages. A number of calculations were conducted to assess trends in dynamic stability changes due to many other flight and aircraft parameters.

It was found that the gyroscopic moments are induced mainly by the propeller and their influence on dynamic stability of a light aircraft is negligible, whereas in manoeuvring flight the gyroscopic effects should be included into analyses, although for light aircraft they are not strong. Hence there were distinguished two types of gyroscopic effects depending on disturbances of steady flight. They were divided into: weak gyroscopic effects – corresponding to classical dynamic stability and strong gyroscopic effects – corresponding to rapid manoeuvres.
Conclusions include some findings about nature of the gyroscopic effects (i.e. sensitivity of flight stability versus turboprop power unit parameters) and practical recommendations for aircraft designers dealing with new configurations of General Aviation aircraft.

In this dissertation the analysis of disc brake temperature impact on braking torque curve in vehicle’s friction brake is presented. Scientific objective of the thesis is analysis of the braking torque versus time function induced by temperature. Temperature rise results in friction coefficient reduction, which causes a decrease of the braking process efficiency. The issues related to the design, construction, and tests of the friction brakewith emphasis on the impact of temperature on the braking torque are the subject of the dissertation. In order to determine the impact of temperature on the braking torque, a number of laboratory tests was performed. Two test stands, one for friction material testing and the other for full scale brakes testing,were used. The measurements of the braking torque, rotational speed, braking force, and temperature were performed. Temperature recording was made using infrared camera, pyrometer, and thermocouples on the stand for testing friction materials and pyrometer only on the stand for testing full size brakes. As a result of the tests, the existence of the connection between temperature and the braking torque curves was confirmed.Developed test method can be used to observe phenomena occurring in the friction contact zone, difficult or even impossible to determine using other methods of measurement.At the same time the phenomenon of sudden drop in braking torque, and its re-growth to a level of equilibrium was observed and explained.

In the next part of the dissertation, numerical (FEA) and mathematical models of friction process are presented. Numerical model was created using COMSOL Multiphisics software. As the input parameters, the results from friction material laboratory test were used. The results obtained from the simulation were compared to the laboratory ones showing high level of convergence. The same laboratory results became the source of the braking torque and temperature mathematical models. They were determined using functions estimation approach.

The thesisalso includes the state of the knowledge analysis in terms of friction phenomena, friction materials, full size brakes, laboratory tests, and numerical simulations.

At the end of the dissertation the conclusions are formulated connected to the described laboratory research and calculations, which confirm the thesis. Suggestions for further works on the topic are proposed.

An elaboration of a future aircraft design concept has become increasingly complex due to changes of the basic criteria for evaluating emerging solutions. In the past, the basic performance characteristics of an airplane were the only selection criteria. Today, more and more emphasis is placed on factors such as impact on the environment, cost-effectiveness, or comfort of travel.

The thesis presents a method to optimise parameters of a small aircraft and to be used in the initial phase of a design project taking into account the requirements of aviation safety imposed by the European Union certification specifications CS-23 and a requirement of aircraft competitiveness within the total transport system.

The basic design decisions regarding a future aircraft, including the selection of basic parameters are taken in the initial phase of a project (a definition of requirements, a conceptual design, a preliminary design). It means that most of the decisions concerning a future aircraft, including decisions significantly affecting aircraft competitiveness, for both, a manufacturer and an operator, are taken before the stage of a technical design. However, in this phase of a project, it is extremely difficult to evaluate achieving project goals due to the imprecision of requirements and design parameters, lack of knowledge of any ongoing interactions among parameters and uncertainty of analysis and calculations. A solution to this dilemma is to increase knowledge of the early stages of a design process.
The method is based on a mathematical model of aircraft and the multidisciplinary design optimisation (MDO) and the method covers the basic areas of aircraft design: aerodynamics, aircraft structure, performance and expected operating costs.

First, I determined the basic requirements for future aircraft by defining project goals accompanied by a set of basic design parameters. I select these basic parameters to define a configuration, that corresponds most accurately to the goals.
The objective function was defined as the value of the direct operating costs per 1 passenger-kilometre. Evolutionary algorithm was applied to solve the optimization problem.

The competitiveness requirements were formulated basing on a concept of the Small Air Transport system (SATs). The SATs vision was developed by the consortium within the projects of the 6th and the 7th Framework Programme of the European Union. The SATs is based on a fleet of small aircraft and rotorcraft equipped with 4 to 19 seats, and operating within an integrated and intelligent transport management system, at small airports and aerodromes. The SATs conclusion underlines significance of a fleet of turboprop aircraft.

The first stage of my study was to analyse the current state of the art in three thematic areas: the small aircraft transportation theory, the design process at the stage of concept development and preliminary design, and the modelling, computer simulation and numerical optimisation methods.
I used the analysis results to formulate a mathematical model of aircraft. It consists of four modules: a mass model, a performance model, a direct operating costs model and an optimisation algorithm.

My next step was elaboration of the simulation model and the simulation program. The simulation model was elaborated using Mathcad software. The basic aim of the simulation model was to validate the structure of the mathematical model, the completeness of data and algorithms.
I coded the simulation program in the Visual Studio environment using C++ programming language.

Then, I carried out the optimisation of design parameters of the 9-seater and the 19-seater as an example of this method application. I compared the optimisation results of my method with the results obtained using the minimisation of the engine power method.

Moreover, I analyse the sensitivity of the objective function with respect to selected parameters of the aircraft. The results facilitate choosing the most significant variables responsible for operational costs.

The thesis includes conclusions from modelling and analysis, and the recommendations leading to improve the competitiveness of small aircraft.

The subject of this doctoral dissertation focuses on the early detection of damage to the nickel-based alloys using nondestructive methods. The degradation of the material structure is a dangerous phenomenon from the safety point of view. The deformation of the structural materials causes the structure damage and in effect destroys the material. Analysis of damage growth consists of observation of changes in the structure of the material subjected to a specified deformation. In order to determinethe degradationof materialsbothdestructiveandnon-destructive methods there are used. An important advantage ofnondestructive methodsisthat they do notrequire asampleof materialfromthe tested objectto determine itsmaterial properties.
The main purpose ofthis study was toinvestigate the possibilityto detectdefectsat an earlystage of theprocess ofdegradation of the material, with application ofcurrently used or modified methodsof nondestructive testing. A stage preceding the creation of the dominant crack is an early stage in the process of material damaging. At this stage, cracks, formed as a result of accumulation of microdamages, are below 0.5 mm in size.
To detect changesin the structureof the materialanultrasonicandeddy currentmethod are selected. Inconel718 was the materialused to testand evaluate the degradation. Inconel is a family of alloys of austenitic crystal structure based on nickel and chromium. These superalloys are characterized by high heat resistance, strength and creep resistance at high temperatures, surface stability and resistance to corrosion and oxidation. Therefore Inconel alloys are specially applied in extreme working conditions – in power engineering industry, aviation and aerospace.
The tests were conducted using a new type of specimens of variable cross-sectional area measuring part. This allowed to obtain a continuous distribution of plastic strain in that part of the specimen. The deformation that varies along the axis of the sample enables an analysis of damage induced by plastic deformation. The proposed method enables replacing a series of specimens by one sample.
Methods of material damage measuringare based on the assumptionof the correlation between the degree of damage and the measurablephysical quantitycalledthe indicator ofdamage.There was carried out an analysis concerning measures and damage indicators. In ultrasonic testing attenuation of ultrasonic waves and acoustic birefringence were selected as indicators of damage. In the case of the eddy current method there was selected a change in the phase angle of the impedance in the material. The values of these indicators were measured for specimens of the material before strength tests.
In order to obtain a certain deformation of the material samples static tensile tests and creep tests were carried out. Thedamage indicators were measured again. In the result there were obtained the values of attenuation of ultrasonic waves, the acoustic birefringence, and the phase angle shift of the eddy current, depending on level of material damage in specific areas of the specimen.
Based on Johnson’s model there were determined damage parameters in parts of the measuring specimens. The correlation between thematerial damage degree and nondestructivedamage indicators was determined.
In the summary,it has been concludedthat theappropriatenondestructivetesting techniquescan be used toassess the degree ofmaterial degradation. Using these,it is possible todetect damageat the microstructure level, resulting fromservice loadsandmaterialsrelated to the processof creepand fatigue.Nondestructivetesting techniquesallow the detectionof the changesin the structureof the materialcaused bypermanent deformationat an early stage of damage.

Aim of the dissertation

Liquid impingement erosion is a result of numerous and repetitive impacts of liquid droplets onto a solid body with degradation mechanisms similar to fatigue. The erosion models used so far are based on empirical data and limited selection of material properties.
The aim of this work is to develop a methodology for erosion life prediction of martensitic steels, based on data concerning fatigue properties.

Thesis
Prediction of service life of martensitic steels subjected to liquid droplet erosion can be performed based on fatigue material properties.

Scope of dissertation
• Based on available publications, a literature review on liquid droplet erosion has been presented with an emphasis on material degradation mechanisms.
• Existing models of service life prediction under erosion were analyzed. The following aspects were taken into consideration: impingement loads caused by single droplet impacts, used material properties, structural aspects and thermodynamic erosion conditions.
• A test matrix and investigation plan was elaborated for two types of martensitic steels: 17-4PH and X20Cr13 – materials commonly used in the design of turbomachinery equipment. Tests were setup to match the typical operating conditions.
• As a result of these studies, similarities between the erosion and fatigue mechanisms were evaluated. Among the methods used were: visual examination, magnetic particle inspection, microfractography using scanning electron microscopy, microstructural studies using transmission electron microscopy and X-ray residual stress measurement.
• Analyses and simulations of liquid impacts onto a solid body were performed with numerical methods, such as: finite element method (FEM) and due to complex fluid-structure interactions, presence of fragmentation effects and large deformations smooth particle hydrodynamics (SPH). Obtained results were used to evaluate the stress levels induced by impinging water droplets.
• Based on fatigue approach, a methodology was developed for estimation of erosion incubation period. The stresses and strains generated by a single droplet impingements are evaluated from numerical experiments. Depending on their level, two different methods were used: for high or low cycle fatigue. The randomness of droplet impacts during erosion tests is included with a simplified statistical model. Verification and validation of the developed methodology was performed based on experimental test data.
Conclusions
1. Literature review has shown existence of similarities between the erosion and the fatigue phenomena:
• existence of incubation period, analogous to fatigue life under fluctuating loading;
• increase or decrease of incubation period length as a function of erosion conditions (i.e. impingement speed);
• presence of limiting conditions for erosion occurrence (i.e. minimum speed with other parameters remaining constant) for materials having an endurance limit (such as carbon steel);
• lack of limiting conditions for erosion occurrence (i.e. lack of minimum speed with other parameters remaining constant) for materials (such as aluminum alloys) which do not have a defined endurance limit.
2. Analysis of existing erosion models showed numerous and significant limitations in their applicability. These were found to come from simplifications in model design (being based on empirical data), or lack of sufficient material properties to express the erosion resistance.
3. Degradation mechanisms under erosion showed numerous similarities to fatigue. As a consequence of repetitive load cycles caused by water droplets impingements, the target material has suffered from surface microdeformation and accumulation of microstructural defects. After a the incubation period was reached, the material degradation took form of fatigue microcracks initiation and propagation.
4. The analyzes and simulations of liquid droplet impingements showed that the generated stress levels are sufficient to exceed the fatigue strength of martensitic steels such as 17-4PH. The source of stresses was both: the hydrodynamic interaction between the liquid and the solid, as well as formation of a shock wave. Depending on the erosion conditions, two possible scenarios were observed (for typical turbomachinery operating conditions):
• single impingements generate stresses exceeding the fatigue strength of a given material, however too low to cause plastic yielding;
• single impingements generate stresses exceeding the elasticity limit of a given material.
5. The accuracy of the developed incubation period estimation methodology for models based on low and high cycle fatigue was verified against ASTM G73 test data. It was found to be comparable to typical accuracy of methods used for evaluation of fatigue life.

Recommendations
• Some of the existing simplifications in proposed methodology originate from current limitations in modeling of fatigue on a microscale and under high strain rates. Any progress in those fields should be used, leading to further refinement of erosion prediction accuracy.
• Present study was focused on martensitic stainless steels. Nevertheless, materials such as cobalt based Stellite alloys or titanium alloys are known to exhibit remarkably good erosion characteristics, with comparable tensile properties. Taking into consideration their different physical and fatigue properties, application of fatigue based approach to LDE prediction on those groups of materials should be a part of further research.
• Considering the fact that turbomachinery equipment is designed to poses years of service lifespan, further study should focus on implementation of methods used to estimate infinite life of the material. Ongoing work is focused on feasibility study of Goodman diagram and Haigh diagram application with mean stress correction to liquid droplet erosion problems.
• With known design parameters and operating conditions on erosion (i.e. impact angle, surface roughness), further work should be related to development of design criteria, so that the stress levels produced by a single droplet impingements would be reduced, leading to increase in erosion resistance.

The subject of proposed thesis is a multidisciplinary optimization of inverted joined-wing. In a result of the research an optimization algorithm of whole configuration of joined-wing with electric propulsion is proposed. The optimization process is a global search optimization suitable for preliminary design of joined-wing. Modular algorithm based on automatic geometry generator, FEM solver and aerodynamic panel method is developed. Whole process is optimized to decrease huge computation cost to the minimum.
The general optimization objective is to maximize the range of aircraft for assumed mission, as it is the major disadvantage of electric aircrafts. The payload and battery capacity are fixed. Global, local geometry and structural parameters are selected as a design variables.
Optimization is performed in serial manner – structure optimization is conducted inside aerodynamic optimization step. During structure optimization, strength is checked for few sizing load cases obtained from loads envelope. Only structural parameters are variable at this stage. In the aerodynamic loop objective function is optimized by changing only geometrical parameters.
For optimization purpose a meta-model of response surface is created and then used in next steps. Final optimization is conducted using two stage process. The first stage is the global one and it uses genetic algorithms. The second stage which is gradient based optimization is the local stage that improves first estimation of optimum.
Based on proposed algorithm a program was coded and some tests were done. Aerodynamic calculations were validated by wind tunnel tests conducted in Institute of Aviation. Next, three optimization test cases for UAV and VLA aircrafts were performed. Additionally, a modification of algorithm was proposed that allows to obtain specified longitudinal stability margin. Based on results of prepared optimizations it was proven that proposed algorithm can be successfully used to improve the range of inverted joined wing aircraft.

The thesis presents the analysis of results of experimental investigation which was a part of the research on the catalytic decomposition of highly concentrated hydrogen peroxide. Manganese oxide ceramic supported catalysts were used in the framework of research. Test and preparation stands as well as test equipment were designed in order to perform the activity. Catalyst beds, similar to those used in rocket propulsion, were utilized in the investigation.
The main task was to assess the possibility of application of various heterogeneous ceramic supported catalysts to decompose 98% hydrogen peroxide inside unheated catalyst beds of mono- and bipropellant rocket engines. In order to perform the activity, the number of catalysts supported mainly on α- and γ-alumina were prepared. The active phase for these catalysts were manganese oxides, doped with oxides of several transition metals.
The investigation consisted of four main stages. Initially 46 samples of catalysts were tested inside the catalyst chamber using the unified procedure and test sequence. That enabled to compare performance and select those catalysts that met defined criteria with the highest score. Selected catalysts were then applied to the second stage of the investigation that was performed using a new test setup. The crucial stage of the activity was to define, prepare and test composite catalyst beds. These structures were made by layered distribution of various ceramic supported catalysts, separated by wire mesh screens. Finally the lifetime test of one selected catalyst bed configuration was performed in order to assess the possibility of application of such a structure in a rocket engine.
Based on the results of the performed research the final conclusions were drawn. Further work for the extension of recent investigation was suggested as well.
The investigation was a part of the project “Research on composite catalyst beds for decomposition of hydrogen peroxide to be applied in a monopropellant thruster”, funded by the European Space Agency in the framework of PECS programme. The project was realized in the Institute of Aviation by the research team from Space Technology Department.

This doctoral dissertation aims at examination of Light Aircraft Transport System (LATS) safety. Analysis of statistical data concerning operations of small aircraft undoubtedly indicates on large disparities in the area of safety and reliability level compared to big commercial transport. The main reason behind this is the fact that development of safety related technologies is mostly driven by big airline industry resulting with lack of physical possibility of adopting them to the small aircraft re­quirements and non-proportional price of the item. Therefore, there is a strong need for identification of other solutions enabling improvement of light aircraft safety level without high increase of take-off weight and operational costs. The study focuses on commercial operations on light propeller-driven aircraft with take-off weight below 5760 kg and seat capacity under 10.

The primary objective of the study was analysis of room for improvement in the area of light aircraft safety through:

  • Identification of issues critical for the safety issues and consideration of possi­bilities of limiting their impact;
  • Optimal selection of technical and operational specifications of the aircraft fleet and the whole System.

The methodology was based on identification of the typical mission profile of the LATS aircraft and set of 26 critical safety issues with regard to their weights on par­ticular flight phases. There was result increase in mission reliability with insignificant increase in aircraft operational costs.

Applied methods originated from statistical analysis and theory of probability. Of the special importance was Reliability Diagrams theory enabling modelling of Mean Time Between Incident or Accident (MTBIA). Mathematical model was calibrated with use of statistical data gathered and processed in the framework of analysis of 194 NTSB accident and incident reports occurred in the United States between 2008 and 2013.

The main result of the dissertation was distribution of incidents and accidents occur­rence intensity for particular flight phases. Mathematical model also had capacity of calculation of expected LATS safety level for set of various operational scenarios. In summary, it has been concluded that the most critical problems concerning light air­craft safety are: engine reliability in cruise phase responsible for about one fourth of incidents and accidents; pilot spatial disorientation during cruise phase leading to more than 16% of occurrences; airmanship errors, especially during touchdown phase (4%) accounting for 12% of accidents as well as pilot errors resulted from operations on non-certified or non-towered airports respectively leading to: 7.5% and 5.5% of events.

Additionally, it has been claimed that optimal selection of the technical specification of the aircraft fleet as well as operational features of the whole System would improve the LATS safety level 3,5-fold and increase in the value of MTBIA by 230%. Never­theless, it was concluded that despite the identified potential for the progress in the considered area, the further efforts aimed at safety issues are unavoidable. LATS cannot be considered as acceptably safe, both in terms of technical reliability and human factor performance. The most critical issues are: engine reliability improve­ment, pilot training effectively preventing errors leading to spatial disorientation, airmanship during touchdown or errors committed before engine start. Part of the executed work was supported by the results of ESPOSA and ASCOS FP7 projects.

This thesis concentrates on the problem of identification, estimation and risk analysis in the area of laboratory processes in defined condition for  laboratories participating in accreditation process and laboratories offering their services outside this process.

This thesis presents evaluation model of risk and defined ways of risk management in the identified sources of uncertainty focusing in the area of technical and organizational area of laboratories and specifies a roadmap of risk.

This paper defines a methodology for the approach to the risk assessment in research laboratories. Indicates sources of information related to the risk and tools for their analysis. This paper presents also the results of analyzes based on the conducted questionnaire and the results of internal and external audits in the area studied laboratories. The implementation in line with laboratories strategy have a significant impact on improving the functioning of the laboratory activities.

Analysis of the results conducted questionnaire is based on the tools such as analysis of the risk structure index (named WSR), grid percentile calculation of risk, risk coefficient analysis between perspectives and their strength and linear regression analysis and ranking. To carry out the analysis of raw data from the results of internal and external audits author uses the following tools: analysis of the percentage of risk, analysis of Pareto distribution of risk analysis and analysis of standardized risk ranking.

The above-mentioned methodologies of analysis of questionnaire results and audit were the original solution in terms of risk undertaken subject in laboratory practice.

Ability to manage effectively the risk in the context of the highest quality of services to the customers will allow laboratories to gain a competitive advantage.

In this dissertation has been presented how geometry of the combustion chamber in compression ignition engine with direct injection influence on the emission of the nitrogen oxides. The choice of the nitrogen oxides had been supported by its special harm to health, the environment and the difficulty in reducing at the level of the formation and elimination from exhaust gases.

The emission of the nitrogen oxides depends on many engines construction factors and fuel injection parameters. In this dissertation, plenty of attention, was put on the analysis of the describing these phenomena literature. It has permitted to eliminate its influence on conducted research beyond the geometry of combustion chamber. Testing was performed on five combustion chambers, which varied in diameter and depth of the chamber but chosen in this way to ensure the same compression ratio.

As a result of the research and simulations it has been confirmed that there is connection between the diameter of the combustion chamber and the level of nitrogen oxide emission.

Presented simulation of turbulence and its effects on the stream of fuel has allowed to prove the thesis which were based on the attached stream theory disintegration and other researchers study concerning on the effect of droplet size and droplet residence time in the combustion zone. Air turbulence and fuel injection in the cylinder and in the combustion chamber simulations were carried out in SolidWorks Flow Simulation. A mathematical movement model of fuel drops in swirling air was developed and its results cover with the simulations made in SolidWorks Flow Simulation.

All conclusion which are included in this dissertation, based on researches and simulations, confirm the thesis of work. The conclusion of this dissertation may provide a guidance in the design of toroidal combustion chambers.

The dissertation presents a comprehensive analysis of the feasibility of using electric propulsionsystems for commercial aircraft, as a replacement for turbofan engines in the 20 30 year time frame. The main study was preceded by the identification of the potential customerneeds and expectations for future propulsion systems. Safety regulations, environmental issues, economic conditions, and maintenance requirements were widely considered. Potential methods and technical solutions, which would allow to fulfill newdemands, were reviewed in terms of pros and cons of specific solutions, and based on that, the juxtaposition of different competitivemethods was presented. Three main types of electric propulsions were discussed: all-electric, hybrid and turbo electric systems, including differentvariants of system architecture. Strengths and weaknesses of each architecture were discussed and their technical limitations were presented. In the next step, thesis focused on the field of electric components, in terms of their efficiency, power density and energy density, as well as their possibilities for further development. Then a fullreview of the currently designed all-electric airplanes and their performance and planned upgrades were presented. In addition, the feasibility of all-electric propulsion for small-business jetaircraft was extensively investigated. Based on the conclusions drawn at this stage of thesis, extensive analysis of a distributed propulsion system, which utilizes turboelectric and hybrid architectures, was performed for regional jet, narrow-body and wide-body classaircraft. The obtained results were compared with performance of the selected base line airplanes which represented three given classes. The analysis was performed in three stages. In the first stage thermodynamic cycle performance of uninstalled propulsion system was calculated. In the second stage the mass of the propulsion system was assessed, and in the third, the aircraft mission analysis was performed. The possibility of reduction of the total mission energy consumption, as well as expected emission reduction were studied. That showed the potential benefits of the use of electric propulsion system, at different time frames and levels of electric devices advancement. The same analysis was also performed for boundary layer ingestion, which can greatly increase the potential benefits. The summary of this study presents conclusions about the eventual use of electric propulsion systems. At the end, the recommendations for future analysis and potential fields of further research were presented.

The presented thesis is analytical in nature and is dedicated to the method for determining indicators of reliability for military vehicles operated intermittently by recording operating events.Indicators of reliability are a helpful element in military logistics.The algorithm of reliability index is so generalized that it can be used to analyze other types of technical objects used in the rescue, transport, and specialized seasonal transport jobs.

The advent of information technology in the logistics of the military has helped to move the traditional paper system of recording operating eventsto the integrated IT military system.It allows to track the usage history of fleets of military vehicles with regard to the individual units of equipment.Polish Armed Forces capable of constant combat readiness maintain the potential of the fight, aids and logistics and transport on the vehicle chassis. Knowledge of the reliability of the various types of vehicles creates the possibility of a proper planning of the mission within the framework of its potential means of transport.
A method of obtaining desired increase of the efficiency of fleet management vehicles utilized irregularly has been presented in this thesis. Developed on the basis of analytical procedures, the algorithm of selection for vehicle (or group of vehicles) to perform the tasks takes into account the allocation of mobile resources, their complexity and complicated construction, the degree of modernity, with the so-called “morally obsolete”, the history of usage – runs, current repairs, planned repairs, operation planned, the amount of spent fuel, oils and lubricants, industry regulations.The obtained results of analytical models and computer simulations carried out demonstrate the validity of the adopted thesis dissertation, which argues that the designated indicators of reliability for individual groups of vehicles can implement the Integrated Multilevel Information System of the Ministry of Defence.

To increase the efficiency of managing military vehicles author proposed to introduce an algorithm taking into account the mobility of vehicle, type of traction – wheeled or tracked, task specificity and the history of the vehicle.The author has also introduced a reserve procedure supported by the results of tests and computer simulations in this paper, the aim of which is to assess the reliability of the vehicle designated for the mission.

A mathematical model has been created, basing on the known test methods used to determine the reliability of a variety of mechanical systems developed.The selection of the minimum necessary and sufficient operating parameters of the vehicle has been conducted, allowing to determine the indicators of reliability of military vehicles at the level of a single copy of the equipment.

A preliminary analysis of the economic effects expected when using the methods developed in the thesis which determine the indicators of reliability, has been made. Comparison of the recording methods currently used in the Polish Armed Forces with those proposed in the thesis, have revealed that the innovative methods will undoubtedly bring a positive effect both in increasing the reliability of carrying out rescue and intervention and will bring savings in the period of awaiting and storage.

At the end, the thesis shows the findings of the analytical considerations supported by an extensive database of various operating types of transport equipment used intermittently in the Armed Forces of the Republic of Poland.

The paper presents the analysis of the reliability and cost of the risk of non-operating vehicles used in long-term rental. The main objective of the study was to develop a model for assessing the truck’s operational efficiency, including both economic and reliability criteria.

The additional objective of the study was to compare three brands of medium-payload trucks used for long-term rental.
On the basis of literature analysis and practical experience, it has been shown that the methods used to evaluate the efficiency of the car operation in many cases are not sufficient. Under the conditions of high competition in the transport services market, it is important to manage the operational risk and anticipate car damage and to anticipate the cost of these damages. From the standpoint of the operational efficiency model, revenue discrepancy and lost customer trust are of great importance.

The dissertationincludes:
1. Theoretical study on the development of a mathematical model of car performance,
2. Simulation studies – numerical modelling of operational efficiency,
3. Experimental operational research on the reliability and the cost of repairing of three selected brands,
4. Expert tests of vehicle reliability and maintenance costs.

On the basis of conducted experiments, numerical and expert investigations, an authoritative model of the efficiency assessment of trucks was developed and validated. The model is based on a cost effective formula. The key feature of the model is that it takes into account the risk of losing customers’ trust in the event of unforeseeable failure of the vehicle due to damage and taking into account the risk of accidental loss of revenue due to truck repair. The efficiency factor presented in the dissertation is a measure of the risk of discontinuity of the vehicle during the rental period and can be used for scientific research as well as for the operational practice of brand choice and truck model. It has been shown that when selecting a vehicle for a rental hire, the investor should, in addition to the price of the vehicle, take into account its reliability, which significantly affects customer service quality and vehicle maintenance costs.

This thesis presents the wide application of industrial installations containing pipes in their construction. The issue of safety during the operation of industrial piping systems, in particular installations for the extraction and transport of hydrocarbons, has been discussed. Two examples of catastrophes caused by a failure of the installation are described, focusing on their causes and effects. An analysis of the factors affecting the risk of failure has been conducted identifying safety key processes occurring during its design, construction, commissioning, operation and disassembly. Author described processes that are used to minimize the risk of failure as well as to limit its effects when it occurs. In assessing the consequences of the failure and the analysis of the procedures, it was found that one of the key factors that determines the magnitude of the problem is the time between the occurrence of the failure and the effective response. A review of available piping repair methods has been made, founding that there is no effective way to quickly and effectively prevent uncontrolled outflow if the installation is completely disrupted for use in areas difficult to access for the crew.

The purpose of the research is to find an effective solution that applied in a fast way enables to limit or block the leakage from the damaged pipe or first of all to connect damaged subsea well.

The thesis of the work is the possibility of using a labyrinth-type seal used, among others in the construction of energy turbines, as an effective and efficient solution that allows to quickly reduce or completely stop leakage from a damaged installation by blocking the outlet, or, above all, connecting a damaged offshore well.

Based on conducted numerical and experimental studies, the author’s solution of the protection of the industrial pipeline against the uncontrolled outflow of hazardous substances was developed and verified. These studies may provide the basis for further development of the proposed solution to develop optimal configurations for individual

As a part of the contemporary fight against harmful organisms attacking forests and agricultural crops in many areas of the globe, pesticides or other water-soluble agents are applied. They are applied in the form of small drops spraying, that settle mainly due to gravity force. The dissertation is focused on the spraying from the air using aircraft, above all, helicopters and planes. Recently, there has been a strong increase in the use of unmanned aerial vehicles as well. The use of such techniques, however, is associated with a strong migration of sprayed material from the areas subjected to treatments over the surrounding areas, especially when the treatments are carried out improperly. It may cause contamination of unintended areas.

Therefore, an attempt to model the process of spraying and settling the liquid drops in the lower atmosphere of the Earth was made. After sketching and analyzing selected ideas and models of previous authors, one could notice a very strong simplification in the description of aerodynamic wakes left by the flying aircraft (especially in very close vicinity of the ground). This seems to be a significantly wrong assumption. Drops are introduced into the atmosphere from atomizers located just below the airfoil or in the middle part of the aircraft. Therefore, the velocity field generated by aircraft in flight has the greatest impact on their movement.

Wind and its atmospheric turbulence is the second, most important factor, especially in cases of vertical air movements. Nonetheless, the agricultural treatments are being carried out in the best weather conditions, thereby eliminating their potential influence. However, it is not possible to eliminate the very strong and unavoidable aerodynamic trace.

Hence, the need to pay attention to the nearest wake of the plane, which can not be modeled using only two vortex lines, as in the most previous models, is very urgent. Most, if not all the existing works, do not take into account the full, three-dimensional aircraft models, including fuselage, gears, struts, elevators or rudders. Only the influence of wings, propellers or rotors, in the form of vortex lines, on the aircraft velocity fields, was modeled. Thus, the main axis of work has been put on the creation of the full, 3D models of both the helicopter and the airplane. The Mi-2 helicopter and the PZL-106 “Turbo Kruk” plane were selected. Analyses were carried out using CFD methods for a side wind and for the windless air as well as for the fully loaded plane and the plane in the final spraying stage, with the minimum level of fuel and chemicals. Lateral distributions of droplets on the ground was obtained, which was then compared to experimental data and to the solutions done by the selected models of other authors for the helicopter, while for the plane the results were compared only to the results obtained by means of other models.

The subject of the dissertation is an analysis of helicopter main rotor including aeroelasticity effects. It is devoted to developing and validation of new computational methods.

Modern helicopter rotor blades design requires taking into account complex aeroelastic phenomena because of their significant impact on the rotor performance and the safety of helicopter operations. Sophisticated computational fluid dynamics and structural dynamics models, available on the market, when coupled together enable such analysis with very high fidelity. However, the computational cost of this type of simulation is usually very high and for this reason it cannot be used in an interactive design process or an optimization run. Complex Fluid Structure Interaction (FSI) models are excellent tools for verification purposes, but the design process requires simpler methods with lower computational costs while maintaining relatively high accuracy and capabilities.

The presented work focuses on development of a new efficient method for calculating helicopter rotor loads, deformations and performance. It uses the well-known Navier-Stokes equations aerodynamic solver – ANSYS Fluent, and modified Virtual Blade Model (based on Blade Element Theory and actuator disk approach) for rotor flow calculation. The dedicated structural dynamics solver, based on an equivalent beam model of a blade and Finite Difference Method, was developed and coupled with the CFD solver using User Defined Functions in ANSYS Fluent software. The connection of the two reduced order models ensured high capabilities in comparison with simulation time.

The accuracy of the created module has been validated with the wind tunnel test data of an IS-2 helicopter rotor model and an UH-60A helicopter rotor, for both hover state and forward flight cases. The method was also verified based on an analysis of the hypothetical Ormiston rotor, which was developed especially for the testing of computational packages. The comparisons showed good agreement of the datain hover andlow-speed cases,but also revealed new research possibilities to improve the accuracy of simplified module in high-speed forward flight cases. As part of the research a second computational module, based on explicit flow modeling around the blades, was also developed. This allowed for a more complete verification of the simplified method, identification of itsusability range, and an accurate estimation of the influence of blade deformations on rotor performance.

The proposed simplified aeroelastic helicopter rotor model combines most of the advantages of using three-dimensional Navier-Stokes solver with relatively low computational costs and high accuracy, confirmed by wind tunnel tests. Therefore, it can be successfully used in helicopter rotor blades design and optimization process provided that its current limitations are respected.

This thesis presents issues connected with designing electric brakes. Author are interested mainly in designing during his own work in Institute of Aviation. The designing process has been presented since the first conception phase. In that phase was made the selection of existed brakes solutions and then was created the first conception of electric brake. In next phase the model was upgraded few times and in the final conceptthe brake was adapted to I-23 landing gear. During the designing changes the model strength was optimized in FEM methods program. Eventually the final model 3D was created and the draft documentation was created from it. In the final phase the prototype was created and then was tested in Landing Gear Laboratory. All these designing issues were taken into account when author showed the designing methodology and methods of finding designing solutions based on literature, experience of designer and people connected with designing in our department.Nevertheless, the author is aware of the extreme of the topic and the opportunity to show diversify of the issues related to the design. In order the author presented the selected issues which were the most interesting and important. Also, the author sees the gap and the lack of thesis related with designing methodology and methods.

It was presented a comparison between the electric brake and existing hydraulic brakes. There were shown the theoretical issues related to the whole process of airplane landing.

One of the most important part it was created the electric brake and comparison to hydraulic solution. The most important part of the thesis were the laboratory tests of electric brakes, which were performed. The tests, parameters, machines, analysis were described in detail. The tests were performed based on the hydraulic brakes methodology.

Sounding rocket development is a significant step preceding launch vehicle programmes. It is an important element of space technology. Increased interest in space transportation in recent years led to plans of introducing new suborbital vehicles to the market. However, despite dozens of years of suborbital flight, today’s designs use similar technical solutions as historic ones. Often non-optimal configurations, in terms of vehicle sizing and propulsion, are used, what leads to decreased performance.

This thesis presents the topic of design and development of small suborbital rockets. It has the form of a series of articles, published in scientific journals and proceedings of international conferences.All papers are strictly connected with the topic of increasing performance of sounding rockets. Modification of parameters of rocket propulsion systems is considered along sizing and focus is given to small rockets used as technology demonstrators.
The thesis of this work is the following: Adequate selection of vehicle configuration and determination of propulsion system design parameters enables increasing overall rocket performance. This relatively general statement enables a flexible approach in terms of providing numerous examples of a wide range of rockets up to 200 kg of mass.

The aim was to present possible suborbital missions of small vehicles, including reaching the Von Karman line, which is commonly regarded as the verge of space. This thesis consists of descriptions of methods of increasing rocket performance. Thrust level, firing duration and nozzle optimisation are considered. Apart from results of numerical analysis, several experimental vehicles with different propulsion systems are shown. A multidisciplinary approach enables providing details considering the design process. Guidelines for developing small suborbital rockets are provided. The thesis is also to be used as a guidebook describing sounding rocket technology development in Poland in the last five years. The series of articles has been finalised thanks to statutory funding of Institute of Aviation.

This doctoral thesis examines the dynamic stability of the unconventional joined wing aeroplane. Aeroplane stability is usually a critical factor that determines its operational safety. Given this, it is obligatory to perform the stability evaluation of a new aeroplane before its initial flights are initiated. It is particularly important in the case of innovative construction, in which the flying qualities are not well known yet.

Therefore, the main aim of this doctoral research was to evaluate the flying qualities of the unconventional, inverted joined-wing aeroplane configuration based on the ILX-23 MOSUPS aeroplane. Particular attention was paid to the evaluation of the dynamic stability of the aeroplane. The stability of the aeroplane was analysed with the use of various mathematical models of aeroplane motion along with the analysis of the data acquired during flight tests.
Before numerical analyses were performed, the input data were prepared based on the aeroplane aerodynamic characteristics received from wind tunnel tests. The aerodynamic characteristics of the aeroplane in unsteady states were determined using two different numerical methods for fluid mechanics. Based on these, preliminary analyses and dynamics simulations were performed, that eventually became a valuable source of information for the pilot before flight tests campaign started.

Data received from flight tests were then analysed. Some specific manoeuvres describing an aeroplane response for the steady state flight disturbances were retrieved from the data. These were used to make a qualitative and quantitative evaluation of the aeroplane modes of dynamic motion. Afterwards, the data from flight tests were also used to validate the numerical model of the aeroplane dynamics.

Numerical analyses were conducted to assess the aeroplane flying properties based on the aerodynamic and mass data reflecting the aeroplane configuration from its final flights. These analyses enabled to determine any major parameters that are used to describe longitudinal and lateral-directional modes of motion. While examining the changes in the aeroplane flying properties that occurred as a result of the vertical stabilizer modification, it was demonstrated that it is possible to improve the joined wing aeroplane flying qualities in a predictable manner.

The findings were examined against the respective legal regulations, the result of which indicates good flying qualities with regard to the formal requirements. The same results were then compared with the results of the flight tests. By doing so, the numerical model was successfully validated, since in most cases, its results were consistent with the results retrieved from the flight tests. Moreover, the examination also included how the changes of input data influence the final results. It demonstrated low sensitivity of the numerical model, and thus, high confidence in the final findings. Several recommendations for aeroplane modifications were also made in order to indicate further possibilities of flying qualities and performance improvements.

Ground Vibration Tests (GVT) are a standard type of tests in aircraft building. They are based on the identification of structure resonances in accordance with the procedures resulting from the properties of a linear model of a single degree of freedom.

In the PhD thesis, the issues which despite of a correct completion of the test procedures can question the reliability of some results, and can escape the methods of estimation of the measurement errors were analyzed. These problems were noticed by the author during works carried out in the Institute of Aviation research laboratory. In accordance with the thesis, an analysis of such cases has been made. These cases have been called as possible reasons for the unreliability of results.

The basis of analyses and considerations are chapters containing the measurement error theory and the definitions and procedures of Ground Vibration Test.
In the first of the chapters dedicated the author’s own research, the error and uncertainty of measurement of the experimentally determined resonance frequency are discussed. It is done to show the incomparably greater impact of the device mass used for the flexible suspension of the test object on the measured frequency. Despite the fact that in the GVT process much attention is paid to the elimination of suspension stiffness, the author notes that also the mass of the suspension device located in a neutral location for some modes of resonance vibrations may have a negative effect on the reliability of other resonance test results.

In another chapter, the issue of an influence of excitation force magnitude on the reliability of tests is discussed. A characteristic feature of mechanical structures is a nonlinear characteristics of resonant frequency for small vibration amplitudes. The paper analyzes a part of this characteristics, an appropriate model for its interpretation has been chosen, and it has been concluded that the internal dry friction of the structure is responsible for this part of nonlinearity.

This dissertation also focuses on a possibility of interpreting selected cases of close-frequency resonance phenomena through dynamic vibration absorber. For the case of close-frequency resonances, the effect of omitting one of the pair of resonances on the flutter calculation results was examined.
Examination of the issues above is a proof of the thesis that in some cases there is a threat of reliability of Ground Vibration Test results unrelated to classic measurement errors.

The Small Aircraft Transport System (SATS) idea assumes using up to 19 seater airplanes for passenger transport. Unlike traditional airlines that operate according to a schedules covering several months, a small number of passengers enforces frequent  adjustment of flights to changing demand. Therefore, it is necessary to develop a method of managing fleet, adapted to SATS needs.

The purpose of the work is to develop methods for optimal management of aircraft fleet operation in SATS. Input data are times and cycles to maintenance  checks, fleet and personnel location and transport service demand in a given time period. The output is aircraft and personnel routing and maintenance plan.

In order to carry out the stated task, a novel space solution model was developed that enables considering exclusively physically feasible solutions, adapted to parallel computing. The task is solved using evolutionary algorithm based optimization heuristics.

The result of work is method of finding optimal routing of aircraft and personnel that meet operational requirements and ensures completing transport task. Its validity was verified through computing test tasks using developed software that take advantage of parallel computing with CUDA architecture (Compute Unified Device Architecture) technology. The method can be used to solve other similar problems, with different vehicles or carrying out other work.

The achievement of the work is:

  1. Formulation, in Chapter 4.1, of fully integrated problem of minimisation of operational costs with routing of aircraft, crew and passenger assignment and maintenance plan. These issues are still being solved sequentially in airlines.
  2. Development of a complete model of solution space (Chapter 4.2), that takes into account complex relationships between planning flight routes of aircraft and assignments of pilots and passengers to aircraft, accompanied by spatiotemporal and operational limitations, such as limited flight time (range), obligatory maintenance checks every fixed number of hours or take-off and landing cycles.
  3. Practical development of original concept of solution representation (chapter 5), which allows to limit the search of solution space to solutions that are physically feasible. Innovation in the representation of solutions is in pointing not directly points in a solution space, but instead providing parameters for the algorithm that use it build the solution. The solution-building algorithm is used in evaluation of solutions. Similarly, when moving around a city, we can replace a list of street names with commands: stick to the left / right side. Starting from a particular point, we will always get somewhere, while mixing parts of two street lists (this is how crossover works in evolutionary algorithms) there may be no common point (e.g. lists of streets on two sides of the river) and the effect is obtaining (and processing!) solution doomed to be doomed to be. Intermediate representation was used by an author in his earlier work concerning simpler problem of optimizing the transport of goods. In the presented PhD thesis, implementation of such a solution for more complex problem made it possible to develop a model of solution space.
  4. A practical solution of fully integrated task of aircraft routing, with allocation of pilots, passengers, and maintenance plan. The methodology can be successfully applied to companies operating air taxi or small aircraft in the framework of SATS.

Scaling the methodology up to, for example, airlines is possible, though it requires implementation that can handle processing of much larger data.

Development of the algorithm will make it possible to automate operations planning and will reduce operational costs. Minimizing costs is the goal of the algorithm.

The methodology presented in the work was verified in a series of test tasks, the purpose of which was to check, first of all, taking into account constraints and then finding an optimum. The tests covered satisfying constraints in the network of 5 airports, in a period of one day of flights, which corresponds to the business model of the Small Aircraft Transport System.

The carried out tests confirmed the effectiveness of the presented methodology in the assumed range.

Over the last few years the team of employees of InstytutLotnictwa has developed the concept of Small Air Transport (STMS/SAT), filling the niche between a regular surface transport and a scheduled air transport – on the distances over 200 km, utilizing numerous, though low in volume, passengers’ streams – giving regions a chance to improve their transportation capabilities.

The concept of this System perfectly fits in the European Aviation Strategy Flightpath 2050, it particularly supports getting real of the main challenge of this strategy, which is defined as: “In 2050, 90% of travellers within Europe are able to complete their journey, door-to-door within 4 hours”.

This subject can become Polish specialty and should be scientifically explored. This Ph.D. thesis is an attempt of such exploration. Its author was one of the initiators of the concept of mentioned System; he took role of EPATS, STMS, SAT-Rdmp projects coordinator and was a co-author of idea to include SAT into Clean Sky 2 program, which was executed as part of European Framework Program Horizon 2020.

The thesis focuses on the study of subjects related to the adjustment of parameters of the aircrafts family used to provide transport services depending on the structure of passenger flows, frequency of flights, flight waiting time, the urgency of the trip, distance and the load rate of the aircraft.

Doctoral research projects in progress