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1

Analysis of the application of distributed propulsion to the AOS H2 motor glider

Kuźniar Michał, Orkisz Marek

Journal of KONES

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2019

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Vol. 26, No. 2

85--92

EN

The paper describes the selection of a distributed propulsion for the AOS H2 motor glider (selection of engines, their number, and propellers) and determination of its performance. This analysis is related to the research conducted on environment friendly and hybrid propulsions in various research centres. The main aim of the analyses conducted is to increase the performance of vehicles powered by electric motors. The batteries have a low density of energy, i.e. the ratio of mass to cumulated energy. Instead of a battery set, it is possible to apply a hybrid- electric system, where the combustion engine works as a generator or an electric-hydrogen generator, where the hydrogen cell supports a small set of batteries. One of such flying vehicles, fitting in this trend, is the AOS H2 motor glider built at the Rzeszow University of Technology in cooperation with other universities. It is a hybrid aircraft, equipped with a hydrogen cell, which together with a set of batteries is a source of electricity for the Emrax 268 electric motor. To increase the vehicle's performance (the range and flight duration), it is possible to use a distributed propulsion. This type of propulsion consists in placing many electric motors along the wingspan of the aircraft. Appropriate design of such a system (propeller diameters, engine power, number of engines) can improve the aerodynamic and performance parameters of the airframe. An analysis of the performance for the selected flight trajectory for this propulsion variant was conducted and compared to the performance of the AOS H2 motor glider equipped with traditional propulsion. The consumption of hydrogen was also determined for both systems. The results obtained were presented in the diagrams and discussed in the conclusions.

2

Analysis of the mechanism of fatigue failure of the Refill Friction Stir Spot Welded overlap joints

Kubit Andrzej, Trzepiecinski Tomasz, Bochnowski Wojciech, Drabczyk Mateusz, Faes Koen

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1419--1430

EN

The aim of this work is the experimental investigation of fatigue failure in Refill Friction Stir Spot Welding joints. The specimens for the fatigue analysis were made of 0.8-mm-thick and 1.6-mm-thick 7075-T6 aluminium alloy which is used to fabricate aircraft fuselages con-sisting of a plate skin with a stiffening stringer. The load capacity of joints was determined by tensile/shear tests. Fatigue tests were carried out on an Instron E10000 testing machine at room temperature. High-cycle fatigue tests were carried out under the following conditions: a limited number of cycles equal to 2 _ 106, a frequency of 50 (Hz), and a coefficient of stress cycle R = 0.1. Microstructural features of fatigue fractures for different levels of variable load were examined using Scanning Electron Microscopy micrographs. The analysis of the fatigue fractures reveals that the Alclad layer at the bottom of the weld is a kind of structural notch and in this situation can be the location of the initiation of fatigue cracking. It was found that fracture mechanism depends on the value of load amplitude. Analysis of the SEM micrographs of fatigue fractures shown that the thermo-mechanically affected zone and heat affected zone are sources of fatigue failure.

3

Simulation of rime icing and its effects on aerodynamic characteristics of an airfoil

Sznajder J.

Journal of KONES

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2018

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Vol. 25, No. 3

437--443

EN

A mathematical model for simulation of icing dedicated to simulation of ice accretion and its effects on aircraft aerodynamic characteristics in conditions of rime icing is presented. Pure rime icing occurs at lower temperatures than glaze icing and results in higher roughness of the surface of deposited ice. The model accounts for increased surface roughness, in terms of equivalent sand grain roughness, caused by deposited rime ice, which influences generation and dispersion of heat in the boundary layer. Increase of surface roughness is determined by analytical models created upon experimental data obtained in icing wind tunnels. Increased generation of heat is a result of increased tangential stress on the surface and is quantified in the temperature recovery factor determined numerically by a CFD solver. Effects of surface roughness on the intensity of forced convection are quantified by application of Colburn analogy between heat and momentum transfer in the boundary layer, which allows assessment of heat transfer coefficient for known friction coefficient, determined by CFD. The computational method includes determination of the surface distribution of mass of captured water in icing conditions. The model of freezing of captured water accounts for generation of heat due to latent heat of captured water droplets, temperature recovery in boundary layer and kinetic energy of captured droplets. The sinks of heat include forced convection, heating of super cooled droplets, conduction of heat through the ice layer and sublimation. The mathematical model is implemented as user-defined function module in ANSYS Fluent solver. The results include effects of deposited ice, including increased surface roughness on aerodynamic characteristics of an airfoil.

4

Determination of ice deposit shape and ice accretion rate on airfoil in atmospheric icing conditions and its effects on airfoil characteristics

Sznajder J., Sieradzki A., Stalewski W.

Journal of KONES

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2017

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Vol. 24, No. 2

271--278

EN

Simulations of ice accretion on airfoil in icing conditions were conducted using ice accretion model implemented by authors in ANSYS FLUENT CFD solver. The computational model includes several sub-models intended for simulations of two-phase flow, determination of zones of water droplets impinging on the investigated surface, flow of water in a thin film on airfoil surface and heat balance in air-water-ice contact zone. The method operates in an iterative loop, which enables determination of effects of gradual deformation of aircraft surface on airflow over the surface, which has impact on distribution of collected water, flow of water film over the surface and local freezing rates. The implementation of the method in CFD solver made it necessary to complement the mathematical model of determination of local rates of deformation of aircraft surface with modification of computational mesh around the surface, which must conform, to the deformed surface. Results of simulated ice accretion on NACA 0012 airfoil were compared with results of experiment conducted in icing wind tunnel for a 420 s long process of ice accretion in steady-flow, steady angle-of-attack conditions. Close agreement of values and location of maximum ice thickness obtained in experiment and in the flow, simulations can be observed. For the airfoil deformed with ice, contour determination of its aerodynamic characteristics at several other angles of attack was conducted proving dramatic degradation of its aerodynamic characteristics due to ice deformation.

5

Determination of water collection on two- and three-dimensional aerodynamic surfaces in external two-phase flow in atmospheric conditions

Sznajder R.

Journal of KONES

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2016

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Vol. 23, No. 1

369--376

EN

Simulations of two-phase flow cases consisting of air and water dispersed in atmosphere were conducted using ANSYS FLUENT solver. The computational model was built with the aim of determination of zones of water droplets impinging on the investigated surface, which is a first step towards simulations of ice accretion in flow conditions where super cooled water is present as dispersed phase. It follows Eulerian approach, currently most effective approach for determination of distribution of water collection on two- and three-dimensional surfaces. Dispersed water is treated as continuous phase and its transport equations are being solved along with air flow equations in the whole computational domain. There are two specific factors of this two-phase flow problem. One of them is ratio of air and water density, which is a cause of existence of two time scales in obtaining a numerical solution of this problem: one for convergence of air flow solution and another for solution of flow of dispersed water in the computational domain. This required development of a specific strategy in obtaining a numerical solution in some circumstances important in aerodynamics, especially at high angle of attack with flow recirculation zones on the wing. The other factor is relatively low concentration of water droplets in conditions important for atmospheric icing. The consequence of this is possibility of uncoupling of solution for both phases and narrowing the solution of the phase of dispersed water to a small region of non-uniformity of velocities of the dispersed phase. Results for two objects: an airfoil and helicopter tail rotor blade, exploiting the developed computational strategy will be presented.

6

Application of 3-D fracture criteria for assessment of fatigue strength of composite plate with internal delamination

Romanowicz P.

Journal of KONES

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2016

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Vol. 23, No. 2

301--308

EN

The fracture analysis of the composite plates with circular delaminations working in a regime of cyclic multi-axial stresses is the main object of the paper. Such structures with internal damage are mainly exposed for local or global buckling and delamination propagation under service loadings. Analyses of described phenomena are complex and require application of fracture mechanics and nonlinear analysis. The literature review of experimental and theoretical investigations of composite plates with circular delaminations is presented in the paper. The essential papers including experimental fatigue tests and theoretical techniques for studying of damage propagation growth are cited and crucial conclusions are given. In composite structures with internal delamination, the cyclic compression-tension and compression-compression stresses are the most dangerous. Moreover, the rapid increase of damage propagation occurs in the final stage of structure degradation. Such problem is investigated and illustrated on the example of rectangular plate with the circular delamination. The calculations are made for bi-axial compression and AS4/3501-6 graphite/epoxy material. The fracture analysis is made using different criteria based on the linear elastic fracture mechanics. The criteria are compared with the multiaxial experimental tests made for AS4/3501-6 graphite/epoxy material. It is observed that in composite plate with the internal delamination subjected for compressive loading the complex form of the gap opening occur. Because of this, the 3-D fracture criteria are applied in the investigations. Presented methodology allow for suitable selection of the multiaxial fracture model for analysis of such structures including interactions between different forms of the gap opening. The critical loadings for different layers orientation are estimated and given in the paper.

7

Analysis of effects of shape and location of micro-turbulators on unsteady shockwave-boundary layer interactions in transonic flow

Sznajder J., Kwiatkowski T.

Journal of KONES

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2016

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Vol. 23, No. 2

373--380

EN

Solutions for turbulisation of a part of laminar boundary layer upstream of shockwave on laminar airfoil in transonic flow were investigated by means of solution of Unsteady Reynolds-Averagd Navier-Stokes equations using as a closure the four-variable Transition SST turbulence model of ANSYS FLUENT solver. This turbulence model has the capability of resolving laminar-turbulent transition occurring in undisturbed flow as well as under the influence of flow-control devices. The aim of the work was to investigate possibilities of improvement of aerodynamic characteristics of laminar wing of a prospective transport aircraft in adverse conditions characterised by occurrence of a shockwave over a laminar-turbulent transition region with separation of laminar flow under the shockwave. The subject is important for application of laminar flow technology, offering economic and environmental advantages due to decreased friction drag, into civil transport aviation. Natural laminar-turbulent transition in the investigated conditions takes place with occurrence of “laminar separation bubble” under the foot of a shockwave and the resulting shockwave is intensive and prone to unsteady oscillations, the “buffet” phenomenon, limiting operational range of flight parameters. In order to counteract the harmful effects of natural laminar-turbulent transition in transonic flow two types of turbulators, placed upstream of the shockwave, were investigated. One of them consisted of delta-shaped vortex generators, producing chordwise-oriented vortices. The other consisted of rectangular micro-vanes, perpendicular to flow and to airfoil surface producing vortices of rotation axes oriented spanwise. Effectiveness of both types of turbulators was investigated for varying height and their location on airfoil chord. Both types of turbulators have proved their effectiveness in tripping laminar boundary layer. The specific effects of the tutbulators, different for each type occurred in the region where laminar separation takes place on clean airfoil. As a result, the changes of lift and drag were different for each type of turbulators.

8

Analysis of chosen fuels influence on turboprop engine work performance

Jakubowski R.

Journal of KONES

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2016

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Vol. 23, No. 2

163--170

EN

The analysis of work parameters of a turboprop engine fuelled by various fuels was done in the paper. The turboprop engine model was presented in the beginning. The main feature of this model is description of the flow in the engine as semi-perfect gas model. By the way, the change of fumes chemical composition influence the gas properties as heat constant and isentropic index are determined. Next energy balance of a compressor and turbine was analysed and turbine pressure drop was evaluated. Finally, engine output power was determined. It was done for selected fuels, which could be applied in the aero engines. The results of analyse were presented in the tables and charts and discussed. Summary of the test results with the results for contemporary applied fuel allows drawing the conclusions about the turboprop engine performance change by various fuel application. Main of them refers to the point that higher combustion heat value of fuel and higher heat constant of fumes cause better engine work conditions By this way the hydrogen seems to be perspective fuel of future, because its combustion heat value is three times JET A-1 and by this way it is possible the engine fuel consumption will be lower.

9

An influence of pusher propeller cover on its performance : a concept of wind tunnel investigation

Ruchała P.

Journal of KONES

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2016

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Vol. 23, No. 4

429--434

EN

The paper describes a concept of wind tunnel investigation of the influence of the pusher propeller cover on its performance. The pusher propeller is one of the most popular types of the airplane propulsion, especially in light sport aircrafts and in the UAVs (Unmanned Aerial Vehicles). Its main advantages is that the engine with the pusher propeller does not affect the visibility from the cockpit and allows for placing an electronic equipment (for example, a camera) in the front part of the UAV’s fuselage. One of main disadvantages of pusher propeller is that it is partially covered by the fuselage and the wings of the airplane, thus the slipstream is distorted. This distortion may reduce the propeller thrust and efficiency. It may also cause vibrations of the propeller blades. This fact is well known, however it is difficult to find any quantitative information about reduction of the propeller performance. Taking it into account, it is worth to treat this subject and show a way to enhance the propeller performance. The wind tunnel tests, which concept has been described in the paper, will include measurements of total aerodynamic loads acting on the investigated object and on the propeller. Measurement of velocity distribution in the slipstream (by pressure measurement and by laser anemometry) will be included as well.

10

Pomiar geometrii podwozia samolotu SEPECAT Jaguar GR.1 ze szczególnym uwzględnieniem węzłów kinematycznych

Brewczyński D.

Logistyka

|

2015

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nr 4

8711--8716, CD3

PL

Skanery 3D zyskują ostatnio na popularności z powodu coraz niższych cen oraz dostępności drukarek 3D, które w zestawie ze skanerem umożliwiają szybkie prototypowanie oraz inżynierię odwrotną. Artykuł zawiera opis metody pomiaru geometrii podwozia z wykorzystaniem samopzycjonującego ręcznego laserowego skanera 3D poza laboratorium. W trakcie pomiarów uzyskano dane, które po dalszej obróbce pozwoliły na wyznaczenie pozycji oraz orientacji wszystkich 14 węzłów kinematycznych mechanizmu podwozia głównego samolotu SEPECAT Jaguar GR.1 oraz wymiarów jego elementów. Pomiary posłużyły również do wykazania możliwości oraz ograniczeń bezkontaktowej metody pomiarowej z wykorzystaniem skanerów laserowych. W trakcie badań stworzono instrukcję pozwalającą na korzystanie z skanera 3D przez osoby na co dzień niezwiązane z tego typu urządzeniami. Wykonane pomiary w przyszłości mogą posłużyć do stworzenia modelu kinematycznego podwozia co pozwoli na badanie zakresu ruchu oraz może przyczynić się do optymalizacji przestrzeni roboczej w mechanizmach podwozi innych samolotów.

EN

3D scanners are gaining in popularity recently because of increasingly lower prices and the availability of 3D printers, which are included with the scanner enables rapid prototyping and reverse engineering. The article contains a description of the main gear geometry measurement method using hand self-positioning 3D laser scanner outside the laboratory. During the measurement data obtained which, after further processing allowed to determine the position and orientation of all 14 kinematic nodes of the airplane’s main landing gear Sepecat Jaguar GR.1 and the dimensions of its components. The measurements also served to demonstrate the possibilities and limitations of contactless measurement method using laser scanners. In the study developed instructions for the use of a 3D scanner by people every day unrelated to this type of devices. Measurements carried out in the future can be used to create kinematic model of the landing gear to allow for testing the range of motion and may help to optimize working space in the mechanisms of other aircraft landing gear.

11

Perspectives on avation training in Polish Universities

Marszałkiewicz J.

Czasopismo Techniczne. Mechanika

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2015

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Y. 112, iss. 4-M

93--101

EN

This article presents the potential for development of aviation education at Polish Universities with a focus on aircraft mechanics training certified by the Civil Aviation Authority in Warsaw and the European Aviation Safety Agency (EASA). An engineering graduate who obtains such a licence in addition to having a diploma would have no problems with finding a suitable employment.

PL

W artykule przedstawiono potencjalne możliwości rozwoju kształcenia lotniczego na polskich uczelniach, z naciskiem na szkolenie mechaników lotniczych certyfikowanych przez Urząd Lotnictwa Cywilnego w Warszawie oraz Europejską Agencję Bezpieczeństwa Lotnictwa EASA. Absolwent studiów inżynierskich, który obok dyplomu, miałby tego rodzaju licencje, nie powinien mieć problemów ze znalezieniem dobrej pracy.

12

Non-contact measurement of geometrical parameters in landing gear using the handheld 3D laser scanner

Brewczyński D.

Journal of KONES

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2014

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Vol. 21, No. 3

23--28

EN

Laser 3D scanners are becoming widely used in many industrial branches. They can be used for prototyping, moulds' designs, special tools creation, reverse engineering, quality control. Also in medicine have been used in the generation of digital 3D files body parts or prosthetic. They are also used in diagnostics to analyse the wear of machine parts, deformation analysis of composite structures, creation of digital objects for FEA analysis. The article includes a description of the noncontact method of geometry measurement using handheld 3D laser scanner REVscan based on geometrical measurements of the MIG-29 aircraft landing gear example. During the analysis performed a complete scan of the landing gear with a resolution of 2 mm (accuracy of 0.05 mm) and a scan of critical points with a resolution of 0.2 mm (0.05 mm accuracy). Subsequently, an attempt to determine the position of characteristic points of connections is by editing the resulting cloud of points. During measurements has been shown the advantages, disadvantages and limitations in the use of non-contact method using 3D laser scanners. Collected data was used to find characteristic point of landing gear in main reference system. Two computer programs were used for data processing. First VXelements software is used to calibration, configuration of the scanner and collecting data. Second Geomagic 3D software allows extensive data processing.

13

Modification of aerodynamic wing loads by fluidic devices

Stalewski W., Sznajder J.

Journal of KONES

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2014

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Vol. 21, No. 3

271--278

EN

Airplane wing load control systems are designed for modification/redistribution of aerodynamic loads in order to decrease risk of structural damage in conditions of excessive loads, to improve passenger comfort in turbulent atmosphere or to act as flight control systems. Classical examples include systems involving symmetric deflections of ailerons reducing wing root bending moments (Lockheed C-5 Galaxy) or deflections of spoilers stabilizing landing approach path (Lockheed TriStar). The fast development of Micro Electromechanical Systems and their application in Flow Control System opens the perspectives of designing practical wing load control systems based on fluidic actuators, modifying local aerodynamic loads by inducing changes to flow, for example, by inducing flow separation in the boundary layer or modifying Kutta condition on the trailing edge. This is the principle of operation of novel concepts of flow control actuators proposed by Institute of Aviation and discussed in the paper. The systems include actuators in the central part of the wing section, reducing local lift similarly to classical spoilers and actuators on the modified trailing edge, acting similarly to ailerons. The potential advantages in comparison to classical devices include potentially shorter reaction time because of avoiding the necessity of moving large surfaces against high dynamic pressure, which is important in conditions of fast-changing loads in turbulent atmosphere.

14

Analysis of the wheel orientation angles in lockheed F-104S starfighter aircraft

Brewczyński D., Tora G.

Journal of KONES

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2013

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Vol. 20, No. 3

79--87

EN

This article contains kinematic analysis of the chassis mechanism used in Lockheed F-104S Star fighter aircraft, which is recently used by the NATO military aviation as an interceptor. The mechanism of the chassis is made up of several smaller subsystems with different functions. The first mechanism is used to eject the chassis before landing (touchdown) and fold it to hatchway after the lift off. The second mechanism is designed to perform rotation of the crossover with the wheel, in order to adjust the position of the wheel to fit it in the limited space in the hold. The third mechanism allows movement of the chassis resulting from the change in length of the damper. To determine the position of the following links of the mechanism was used calculus of vectors in which unit vectors were used to represent the angular position of the links. Often used equation, which describes a polygon vector, and the equation of unknown unit vector possible to determine if the other two and the angles between them are known. Calculations were performed in the three local systems of reference, thus were obtained the simplest forms of solutions for links positions. The corresponding scalar products of unit vectors are elements of two transition matrices. These matrices are needed for the vectors calculation in each of the three coordinate systems. The result of the analysis is to determine the angle of convergence and the angle of heel wheels as a function of variable length of hydraulic cylinder and the length of the shock absorber. It has been shown that length of the shock absorber has little effect on angle of convergence, but has a significant effect on the angle of the tilt-wheel landing gear.

15

Analysis of applicability of thermography to assess health of gas turbine blades

Kułaszka A., Błachnio J.

Journal of KONES

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2013

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Vol. 20, No. 2

237--244

EN

A gas turbine is one of the most heavily loaded, both mechanically and thermally, structural components of an aircraft turbine engine. Hence, the most common reasons for failure are overheating and thermal fatigue of the blade material. It is of great significance for the safety of aeronautical systems that service is monitored; this is carried out to verify the health of these items using all available diagnostic methods. The primary aim is to detect and identify, as early as possible, any probable hazards to the engine. The preliminary assessment of the gas turbine blades condition is carried out via a visual inspection e.g. using a video borescope. During any repair, the preliminary assessment is conducted with a visual method, which is followed with some other non-destructive inspection techniques, e.g. flaw detection, intended to provide full colour images. The essential assessment of the blade condition consists in metallographic examination which precludes further operational use of the item. Probable errors in this assessment usually result in considerable cost of unnecessary repairs of the entire engine. Presented in the paper is the pulse thermography technique being a new NDT method, which is capable of diagnosing changes in the blade condition and to detect early stages of damages to turbine blades. Results of inspections of the blades subjected to high temperature and corresponding changes in signals of thermal response of the blade material stimulated with a heat pulse have also been given. Effects of the testing work have been used to detect changes, against temperature, in thermophysical properties of super alloy used in gas turbine blades. The results have been successfully verified using metallographic examination. To conclude: the thermographic method provides good reliability of the assessment of changes in the microstructure of the blade.