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Tytuł:
The lubricity and sorptive experimental comparatively investigations of engine oils
Experymentalne badania porównawcze smarności i sorpcji olejów silnikowych metodami pośrednimi
Autorzy:
Kałdoński, T. J.
Kałdoński, T.
Powiązania:
https://bibliotekanauki.pl/articles/242866.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transport
projektowanie samolotów
modelowanie
optymalizacja
combustion engine
tribology
lubricity
sorption
engine oils
Opis:
In the paper are presented the results of experimental investigations of lubricity and sorptive properties of selected engine oils. The lubricity properties of oils were tested according to standard method ASTM D2596-69, ASTM D2270-77, and PN-76/C-04147(Polish Standard) on the Four-Ball Test Machine. Sorptive properties of oils were evaluated indirect method, i.e. By means of differential scanning calorimeter DSC141. Two research aims has been realized in this paper. The first aim depended on check the usability of differential scanning calorimetry for indirect assessment of sorptive properties (adsorption) of oils on true material of tribological joint of Four-Ball Test Machines, which was used the next for assessment of lubricity properties of the oils. The second aim depended on conformation of interdependence: have better sorptive properties of oils - have better its lubricating ability. In effect it is showed the thermal measurements for oil-metal system, with the aid of differential scanning calorimeter DSC141, on Four-Ball Test Machines. The worse were lubricity properties of oil (smaller quantity of lubricity additive) the weaker was interaction in metal-oil system and this stand for worse sorptive effects.
W pracy przedstawiono rezultaty eksperymentalnych, porównawczych badań właściwości smarnościowych i właściwości sorpcyjnych wybranych olejów silnikowych. Właściwości smarnościowe olejów oceniano znormalizowaną metodą według PN-76/C-04147 oraz ASTM D2596-69 i ASTM D2270-77 na aparacie czterokulowym. Właściwości sorpcyjne olejów oceniono metodą pośrednią, tzn. Za pomocą różnicowego kalorymetru skaningowego DSC141. Zostały zrealizowane dwa cele tej pracy. Pierwszy cel polegał na sprawdzeniu przydatności różnicowej kalorymetrii skaningowej do oceny właściwości sorpcyjnych olejów silnikowych. Drugi polegał na potwierdzeniu zależności: lepsze właściwości sorpcyjne oleju - lepsza jego smarność. W efekcie sorpcja jest przedstawiana dla pomiarów olej - metal za pomocą różnicowego kalorymetru scanningowego i na aparacie 4 - kulowym. Gorsze były właściwości smarnościowe oleju (mniejsza ilość dodatków smarnościowych), słabsza była reakcja metal-olej i to oznacza gorsze właściwości sorpcyjne.
Źródło:
Journal of KONES; 2007, 14, 3; 261-270
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An application of the heat accumulator and improvement of the DC-DC converter for hybrid-electric vehicles
Autorzy:
Kosztyła, T.
Tutaj, J.
Powiązania:
https://bibliotekanauki.pl/articles/245370.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
simulation
road transport
DC-DC converter
propulsion system
heating system
hybrid vehicle
Opis:
In this article, both problems of the internal combustion-engine’s thermal equilibrium as well as improving the DC-DC converter’s operation in the hybrid-electric vehicle’s propulsion system. The purpose of the proposed amendments is to increase the energy efficiency of the hybrid-electric vehicle’s propulsion system. Such a hybridelectric vehicle in city traffic is characterized by intermittent operation of the internal combustion engine with long pauses, which causes difficulty in obtaining and maintaining the desired operating temperature of the internal combustion engine, especially at low outdoor temperatures and intensive use of the heating system inside the hybridelectric vehicle. The result is the increased emission of noxious exhaust gas components and increased fuel consumption. The proposed solution to this problem is to apply heat accumulator in the cooling system. It is stored in the waste heat from the cooling system used to obtain and maintain the internal combustion engine’s nominal operating temperature. The paper presents the results of simulation analyses the impact of applying heat accumulator in the hybrid-electric vehicle driving in city traffic, at different ambient conditions, such as: air temperature, internal combustion engine’s load and the frequency and length of stops. The proposed algorithm for controlling the circulation of the cooling liquid ensures as soon as possible to achieve and maintain the internal combustion engine’s temperature. Furthermore, the temperature of the operating medium can be adjusted depending on the operating conditions of the internal combustion engine. Experimental studies, on the example of the Toyota Prius and Yaris, confirmed the desirability of the use of the proposed solution. Improving the DC-DC converter’s current is to change the configuration by the use of a two-phase DC-DC converter – instead of a single-phase DC-DC converter, supplying a DC-AC inverter of the DC motoring the hybrid-electric vehicle’s propulsion system. This article also includes waveforms for comparison of the properties of both DC-DC converters.
Źródło:
Journal of KONES; 2016, 23, 3; 263-270
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preventive maintenance with imperfect repairs of vehicles
Autorzy:
Okulewicz, J.
Salamonowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/246462.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transport
maintenance
preventive replacement
imperfect repair
statistical diagnosis
Opis:
A vehicle ability to realise transport tasks may be restored by repairing only failed elements. This is called imperfect repair as the vehicle is not as good as new after such a repair. Preventive replacement is an example of imperfect repair as well. The advantage of such maintenance is that it enables controlling a reliability level of a fleet of vehicles. Sets of vehicles elements which should be replaced in that aim are derived on a base of statistical diagnosing with use of data about elements failures. The acceptable level of a failure risk while executing transportation tasks has been taken as a criterion. An algorithm for selecting elements for preventive replacement has been developed. It was shown that a level of a fleet reliability can be controlled by changing an order of a quantile function in coordination with a number of redundant objects. A computer simulation model of the vehicle fleet was used as an example to illustrate derived dependencies. In particular algorithm for selecting elements for preventive replacement, graph of model states, graphical interpretation of calculating new quantile orders, simulation experiments results for system n out of n, simulation experiments results for d = 2,5 are presented in the paper.
Źródło:
Journal of KONES; 2007, 14, 3; 485-494
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi - material design optimization of a bus body structure
Autorzy:
Korta, J.
Uhl, T.
Powiązania:
https://bibliotekanauki.pl/articles/247771.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
weight reduction
bus structure
structural optimization
multi-material design
Opis:
In the recent years the safety and eco-friendliness have gained much of attention of the automotive stakeholders. These two characteristics are especially important in the case of mass transportation vehicles, such as buses or coaches, which are in continues use for long periods of time, covering significant distances. In such situations, the economical aspects play major role for the transportation companies which try to minimize operational costs of their fleet, by choosing vehicles with reduced fuel consumption. In order to obtain improvements in all the mentioned areas and hence to strengthen their position on the market, bus manufacturers have recently turned their attention to multimaterial design strategies. Structures built in that manner consist not only of regular steel parts, but contain also a mix of components made from various lightweight materials like aluminum alloys or composites, which allow for significant reduction in vehicle curb weight. However, due to the differences in mechanical characteristics which are especially evident in the case of laminates, the material substitution is not a straightforward task. In order to find the material distribution pattern that meets all the requirements, a great number of prototypic numerical models must be prepared and tested. To ease the search for the final solution, optimization techniques can be applied into the design process, allowing for automatic design modifications and assessment of the obtained results. The paper presents an attempt of enhancing the operational characteristics of a bus body structure with simultaneous reduction in the structural weight. In order to find the optimal component configuration, a multimaterial optimization was employed and supplemented by sensitivity and robustness analyses. Such a technique helps to discriminate the over-optimized solutions that are often pointed out as the most desirable by the optimization algorithms which neglect the uncertainties of the analysed system.
Źródło:
Journal of KONES; 2013, 20, 1; 139-146
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical model of bullet - barrel system
Model numeryczny układu lufa - pocisk
Autorzy:
Łazowski, J.
Małachowski, J.
Niezgoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/241651.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
lufa
pocisk
modelowanie numeryczne
barrel
bullet
numerical modelling
Opis:
Aktualnie, projektowanie uzbrojenia w dużej mierze opiera się na metodach analitycznych, które nie pozwalają na znaczną poprawę parametrów broni w zakresie odporności udarowej. Szczególnie istotna jest analiza dynamiki dla ruchu pocisku w lufie na stożku przejściowym i ustalenie optymalnych parametrów procesu. Na styku lufy i pocisku zachodzą bardzo złożone procesy termomechaniczne. Oddziaływanie to powoduje powstawanie na powierzchni styku ciał ciepła a w konsekwencji zmian właściwości mechanicznych. Dodatkowo charakter współpracy obu ciał obarczony jest często brakiem symetrii wynikającym między innymi z niedokładności wykonania elementów, nieodpowiednim osadzeniem pocisku w lufie oraz niejednorodnością materiałów. W skutek takiej złożoności zjawisk, której konsekwencją są np. zmienność współczynnika tarcia czy również drgania pocisku i lufy, ogólne analityczne wyznaczanie stanów naprężeń i stanów krytycznych w sposób ścisły jest niemożliwe. Jedyną skuteczną metodą może być w tym przypadku modelowanie numeryczne. W pracy przedstawiono próbę analizy stanu wytężenia powstającego podczas szybkozmiennych procesów w trakcie współpracy pocisku z lufą. Przedstawiono model numeryczny obiektów i zaprezentowano wyniki analizy w formie planów warstwicowych. Narzędziem zastosowanym do analizy był pakiet obliczeniowy LS-DYNA umożliwiający symulacje w zakresie nieliniowym z jawnym krokiem całkowania.
Currently the design process for armament equipment mostly employs very known and traditional analytical methods. But in many cases this kind of approach is not sufficient and effective, especially for gun parameters related with impact resistance. Very crucial for proper dynamic bullet movement in the barrel are geometric dimensions. In the contact areas between a bullet and a barrel appear some thermo-mechanical phenomena. Additionally, the cooperation process between these two components is encumbered because of the asymmetry caused by the inaccuracy of production process and the inhomogeneity of used materials. Finally, the mentioned reasons produce some unwanted effects like: bullet and barrel vibrations, problems with friction phenomena, etc. In such situations, the typical engineering approach in design process is unable to take into considerations all such local and very complex effects. Therefore, this paper presents is a trial of numerical methods application, which allow perform full analysis process of interaction between bullet and barrel. The models of these two bodies were developed using FE method. The numerical calculations were performed using LS-DYNA code. The main goal of the research was focused on contact problem. In the paper authors enclosed the initial results of the dynamic simulations.
Źródło:
Journal of KONES; 2007, 14, 1; 261-266
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preliminary concept of numerical modelling of combustion process for gunpowder using LS-DYNA code
Wstępna koncepcja numerycznego modelowania procesu spalania ładunku miotającego w systemie LS-DYNA
Autorzy:
Łazowski, J.
Małachowski, J.
Niezgoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/241653.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
lufa
pocisk
modelowanie numeryczne
balistyka wewnętrzna
spalanie
barrel
bullet
numerical modelling
internal ballistic
gunpowder burning
Opis:
In this paper the preliminary concept of numerical modelling of combustion process for gunpowder is presented. Such new computational methods like finite element analysis gave us opportunity to simulate such energetic and high-frequency process like pressure wave generation caused by chemical reaction. The main product of this process is a blast wave, which interacts at the first stage with surrounding (bullet and shell) and finally impel a bullet movement. In the considered case, the detonation product from gunpowder burning couple "produced" gas in Eulerian domain with the barrel-bullet system described in Lagrangian domain. In the performed analysis, the authors noticed some unwanted effects like asymmetry, which is probably related with the finite element mesh and computational errors. In the next conducting investigations some optimisation procedures related with a bullet movement in a barrel will be employed. The successful solution of such complicated problem like a proper simulation of the internal ballistic phenomena with taking into account all dynamic effects can significantly improve the problem of shooting accuracy. The initial calculations were performed using LS-Dyna code. At this stage the presented results have a qualitative character.
W pracy omówiono koncepcję symulacji komputerowej spalania materiału wybuchowego miotającego w układzie lufa- nabój. Takie nowoczesne sposoby obliczeniowe, oparte na metodzie elementów skończonych mogą dostarczyć możliwości symulacji szybkozmiennych procesów energetycznych wynikających ze zamiany energii chemicznej prochu na ciśnienie gazów prochowych i w konsekwencji w energię kinetyczną pocisku. Okazuje się, że zamodelowanie wytwarzania produktów spalania materiału miotającego jest zadaniem trudnym. W takich ekstremalnych warunkach charakter współpracy obu ciał może być obarczony np. brakiem symetrii wynikającym między innymi z asymetrycznego rozkładu ciśnienia produktów spalania materiałów miotających. W przypadku modelu dyskretnego koncepcja ta może zostać wykorzystana do rozwiązania problemu głównego balistyki wewnętrznej i optymalizacji konstrukcji układu lufa - nabój oraz symulacji właściwości dynamicznych rozpatrywanych obiektów w różnych fazach współpracy. Poniżej przedstawiono klasyczne sformowanie modelu dla broni lufowej oparte równań matematycznych i sposób zaimplementowania w modelu dyskretnym. Rozważania zilustrowano przykładowymi wynikami. Pracę realizowano przy wykorzystaniu licencjonowanego pakietu obliczeniowego LS-Dyna. Przedstawione wstępne wyniki mają charakter jakościowy.
Źródło:
Journal of KONES; 2007, 14, 1; 255-260
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling influence of temperature for assessment of wear elements of frictional joints
Modelowanie wpływu temperatury na ocenę zużycia elementów skojarzeń ciernych
Autorzy:
Pakowski, C.
Kałdoński, T. J.
Kałdoński, T.
Powiązania:
https://bibliotekanauki.pl/articles/243040.pdf
Data publikacji:
2007
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
tarcie suche
rozszerzalność cieplna
zużycie tarciowe
dry friction
thermal expansion
abrasive wear
Opis:
In the article is presented continuous method for measurement of wear in conditions of technically dry friction of tribological cinematic pairs type pin-on-disk of T-11 tester, for example. Also is discussed modification of measurement system tester, which it makes possibility synchronization measurement respecting angle position of counter-sample. For six selected joints is appointed a correction for thermal expansion in dependence on temperature offrictional pair as well on speed of temperature change. For continuous of recorder temperature and displacement are carried out research wear for typical materials as well as is measured total wear after finish test. The analysis of obtained results shows existence of correlation between total linear experimental wear and analytical value of total linear wear takes into consideration correlations for thermal expansion. However, during friction there is not correlation between recorded change of dimensions joint and total wear. It shows correction this model. Results calculations of linear wear are overstate in relation to obtained value of wear in direct measurements. It doesn't lower possibility using established method for interpretation results of research wear
W artykule przedstawiono metodę ciągłego pomiaru zużycia w warunkach tarcia technicznie suchego węzła tribologicznego typu trzpień-tarcza przy zastosowaniu testera T-11. Omówiono modyfikację układu pomiarowego testera umożliwiającą synchronizację pomiaru z położeniem kątowym przeciwpróbki. Dla sześciu wybranych skojarzeń wyznaczono poprawkę na rozszerzalność termiczną w zależności od temperatury węzła tarcia oraz od szybkości zmian tej temperatury. Wykonano badania zużycia wytypowanych materiałów, przy ciągłej rejestracji temperatury i przemieszczenia oraz zmierzono zużycie całkowite po zakończeniu testu. Analiza uzyskanych wyników wskazuje na istnienie korelacji między sumarycznym zużyciem liniowym skojarzenia wyznaczonym eksperymentalnie a obliczoną wartością zużycia liniowego, przy uwzględnieniu poprawki na rozszerzalność termiczną. Brak jest natomiast korelacji między rejestrowaną podczas tarcia zmianą wymiarów skojarzenia a zużyciem całkowitym. Dowodzi to prawidłowości przyjętego modelu, konieczne jest jednak poprawienie jego dokładności. Wyniki obliczeń zużycia liniowego są zawyżone w stosunku do wartości zużycia uzyskanych w pomiarach bezpośrednich. Nie obniża to jednak możliwości stosowania przyjętej metody do interpretacji wyników badania zużycia.
Źródło:
Journal of KONES; 2007, 14, 2; 347-353
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Propeller optimization for small unmanned aerial vehicles
Autorzy:
Kusznir, T.
Smoczek, J.
Powiązania:
https://bibliotekanauki.pl/articles/246608.pdf
Data publikacji:
2017
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
unmanned aerial vehicles
particle swarm optimization (PSO)
airfoil modelling
Opis:
Small-unmanned aerial vehicle propellers usually have a low figure of merit due to operating in the low Reynold’s number region due to their size and velocity. The airflow on the airfoil becomes increasingly laminar in this region thus increasing the profile drag and consequently reducing the figure of merit of the rotor. In the article, the airfoil geometries are parameterized using the Class/Shape function transformation. Particle swarm optimization is used to design an airfoil, operating in a Reynolds number of 100,000, which has a high lift to drag ratio. To avoid exceeding geometric constraints of the airfoil, a deterministic box constraint is added to the algorithm. The optimized airfoil is then used for a preliminary design of a rotor; given some design, constraints on the tip chord the rotor radius and the blade root chord, with parameters that achieve the highest theoretical figure of merit. The rotor parameters are obtained using a combination of momentum theory and blade element theory. The figure of merit of an optimal propeller with the same geometric parameters is then compared using the optimized airfoil and the Clark Y airfoil. The optimization is done in MATLAB while the aerodynamic coefficients are obtained from XFOIL. The results of the numerical simulation are presented in the article.
Źródło:
Journal of KONES; 2017, 24, 2; 125-132
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of middle range frequency vibration of aircraft reciprocating engine
Autorzy:
Goliasz, T.
Czarnigowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/246782.pdf
Data publikacji:
2017
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
vibration
aircraft
radial engine
identification
wibracja
samolot
silnik radialny
identyfikacja
Opis:
The authors investigate into vibration characteristics of ASz-62IR-16E aircraft engine. The focus of empirical tests was on the middle frequency vibration range (1000-7000 Hz) that corresponds to vibrations caused by air-fuel mixture combustion process, and defining root mean square of the detected vibration and the amplitude − frequency function. The tests were conducted for seven characteristic engine speeds. Vibrations were measured along three axes of local Cartesian coordinate system. Results indicate directions, frequency ranges and scale of strongest vibrations. The work is a part of identification tests and is intended to provide input for redesign of the engine ignition system. In particular, ASz-62IR-16E engine in test bed, coordinate system for the experiment − designation of axes, sensors mounted on the engine block, comparison of root mean square of full detected range of vibrations (RMS), spectral analysis of vibration for characteristic engine speeds, vibration peaks for all engine speeds, vibrations attributable to combustion process are presented in the article.
Źródło:
Journal of KONES; 2017, 24, 1; 151-158
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fuzzy-Lyapunov based controller for a quadrocopter
Autorzy:
Kusznir, T.
Smoczek, J.
Powiązania:
https://bibliotekanauki.pl/articles/242206.pdf
Data publikacji:
2017
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
quadrocopter
fuzzy control
Lyapunov stability
Opis:
Quadrocopters are nonlinear and inherently unstable systems. To be able to account for the nonlinearities during more aggressive manoeuvres nonlinear control methods need to be utilized to obtain the desired position while at the same time guaranteeing stability. In the article, the quadrocopter dynamics is modelled using the Newton-Euler method. The propeller aerodynamics is modelled using a combination of momentum theory and blade element theory. There are two different control objectives; the 1st objective requires the quadrocopter to reach a desired attitude set point using, while the 2nd objective requires the quadrocopter to track an attitude trajectory. In both cases, Lyapunov stability criterion, in conjunction with LaSalle’s invariance principle, is used to guarantee the system becomes asymptotically stable. In the case of reaching the desired attitude set point, a direct Lyapunov control method is implemented with the control constants determined empirically. For the trajectory tracking, limited knowledge is assumed on the system dynamics and the Mamdani fuzzy controller is used with a rule base that satisfy the Lyapunov stability criterion. The fuzzy membership functions developed empirically and a centre of gravity defuzzification method is used. All simulations are done in MATLAB/Simulink. The results of the numerical simulation are presented in the article.
Źródło:
Journal of KONES; 2017, 24, 4; 125-132
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Direct application of non-thermal plasma to PM reduction from marine diesel engines
Autorzy:
Myśków, J.
Borkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/242305.pdf
Data publikacji:
2009
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
marine diesel engine
exhaust emission
particulate matter
non-thermal plasma reactor
Opis:
This paper describes the experimental method - using non-thermal plasma reactor to cleaning exhaust gases - focused on PM compound. The demonstrator NTP reactor assembly was built as the by-pass in the real exhaust gas after-treatment system, in marine diesel engine. The reactor used to experiment is called - DBD (dielectric barrier discharge) type, The main aim of investigation was to analyze exhaust gas PM compounds under steady load of the engine. Test bench construction enables direct exhaust stream (main exhaust duet by-pass) to plasma reactor exposure with no additional components (coolers, orifices) that can change the exhaust gas properties. A new monitoring PM analyzing system, which can measure soot and SOF in low mass level, has been engaged. It consist of a diffusion charging (DC) detector with a dilution device for soot measurement, and two differential flame ionization detection (FID) method, which uses two FID detectors with separate sample lines. Exhaust emission reduction strategy for ships, Particulate Matters - PM in exhaust gas, non-thermal plasma reactor, experimental test bed and procedure, an example of reactor power measurement, test results provided into seven stages are presented in the paper.
Źródło:
Journal of KONES; 2009, 16, 2; 361-367
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of effects of shape and location of micro-turbulators on unsteady shockwave-boundary layer interactions in transonic flow
Autorzy:
Sznajder, J.
Kwiatkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/242878.pdf
Data publikacji:
2016
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transonic flow control
laminar-turbulent transition
flow simulations
aircraft engineering
transport
vehicles
Opis:
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.
Źródło:
Journal of KONES; 2016, 23, 2; 373-380
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Emission inventory of exhaust gases from oil - fired ship boilers
Autorzy:
Myśków, J.
Borkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/242902.pdf
Data publikacji:
2012
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
ship
oil-fired boiler
marine diesel engine
exhausts emission
Opis:
Regulations concerning the limitation of harmful compounds emission contained in exhaust gases become more restrictive. This is observed within regulations regarding land-based installations and also rules applied to ships of global trade fleet. Other restrictions of vessels emissions, enclosed in rules set out in Annex IV of Marpol Convention 73/78 are gradually implemented and establish emission limits for ship engines. The boiler delivers the heat energy required for fuel preparation for main and auxiliary engines - and also by consuming fuel in its combustion chamber becomes and emitter. This article describes the anticipated methodology of the boiler steam efficiency, depending on the main engine installed. Additionally, fuel oil consumption analysis in various steam capacity range performed using the histograms. The histograms were produced on the basis of service reports of similar units, and combining fuel oil consumption with exhaust emission during operation. A vessel engine report includes monthly machinery abstract and is compiled for a ship-owner on the basis of the log book records. Quantified exhaust emission from auxiliary oil fired boiler contributes determination the overall emissions from a ship.
Źródło:
Journal of KONES; 2012, 19, 4; 487-494
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of turbulence induced by micro vortex generators on shockwave : boundary layer interactions
Autorzy:
Sznajder, J.
Kwiatkowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/245222.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
transonic flow control
laminar-turbulent transition
vortex generators
flow simulations
BAY method
Opis:
Interactions between viscous and transonic effects in air flow around a laminar wing were investigated computationally by means of the solution of unsteady Reynolds-averaged Navier-Stokes Equations. The subject is important from the point of view of applications of Natural Laminar Flow technology in modern, economically efficient passenger aircraft. The research was focused on simulations and analyses of influence of turbulence induced by micro vortex generators on intensity of harmful transonic phenomena like strong shock waves and buffet. Two ways of modelling of the effects of turbulators – the micro vortex generators were taken into consideration. The first way consisted in resolving the shape and inclination angle of the generator in the grid over airfoil and setting the non-slip wall boundary condition on the surface of the generator. The second way, taking advantage of the BAY model of vortex generator, was implemented on orthogonal grid without the need of resolving the shape of the vortex generator in the grid. Calibration of the BAY model was aimed at producing similar distribution of vorticity and velocity circulation behind the model of the vortex generator, as obtained for the grid-resolved model of the vortex generator. The calibration procedure resulted, however, in overestimated turbulisation of the boundary layer in the BAY model, compared to the effects of the grid-resolved vortex generator. The flow simulations indicated, however, that turbulisation of boundary layer induced by micro vortex generators can reduce or eliminate the oscillation of strong shock wave and buffet in off-design conditions and that further adjusting of the BAY model is an efficient strategy for modelling the interactions between viscous and transonic effects in air flow around a laminar wing.
Źródło:
Journal of KONES; 2015, 22, 2; 241-248
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The energetic - superficial and lubricity properties of petroleum products and ionic liquids
Autorzy:
Kałdoński, T. J.
Kałdoński, T.
Pakowski, C.
Powiązania:
https://bibliotekanauki.pl/articles/244139.pdf
Data publikacji:
2009
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
boundary layer
lubricity
ionic liquids
surface tension
contact angle
Opis:
This paper presents the results of comparative investigations on the lubricity and energetic superficial properties of selected petroleum products and new ionic liquids (ILs). Three base oils from polish petroleum refinery (PAO—6, SN-650, SN—350) and lubricity additive (Additin RC2515 EP) have been investigated comparatively to four ionic liquids with imidazolium organic cations and different inorganic anions, i. e. bis (trifluoromethylsulfonyl) imide and tetrafluoroborate. The lubricating ability properties petroleum products and ionic liquids have been assessed according to Polish Standard PN-76/C-04 1 47 (ASTMD2596-69 and ASTM D2270-77) on Four-Ball Testing machine. The investigation range of lubricity properties are limited to the assessment only two parameters i. e. P(t) - seizure load for increasing continuous loading and G(oz) - wear limiting load capacity. The superficial properties of oil compounds and ionic liquids have been assessed by means of modern KSV Sigma 701 Tensiometer. Surface tension o and wetting angle fi were assessed. The obtained results confirmed the possibilities of using tested ionic liquids as lubricants. The best lubricity properties, close to properties of Additin RC2515, had 1—methyl— 3—oktyloxymethylimidazolium tetrafluoroborate.
Źródło:
Journal of KONES; 2009, 16, 1; 239-244
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 67

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