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Wyświetlanie 1-15 z 98
Tytuł:
Analysis of Aerodynamic Characteristics of the Rocket-Target for the „Stinger” System
Autorzy:
Fedaravičius, A.
Kilikevičius, S.
Survila, A.
Patašienė, L.
Powiązania:
https://bibliotekanauki.pl/articles/403737.pdf
Data publikacji:
2016
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
aerodynamics
drag force
drag coefficient
rocket-target
Opis:
This paper presents an analysis of aerodynamic characteristics of the rocket target for the final training of shooting at aerial targets by the „Stinger” system service staff. The governing equations of fluid dynamics are presented and the computational model of airflow around the rocket is developed. ANSYS CFX computational fluid dynamics software is used to compute airflow velocities, pressure, the drag force and the drag coefficient. A practical implementation of the research is presented. Taking into account the simulation results, the rocket-target was designed and manufactured.
Źródło:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa; 2016, 7, 1 (23); 7-16
2081-5891
Pojawia się w:
Problemy Mechatroniki : uzbrojenie, lotnictwo, inżynieria bezpieczeństwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Steady Oseen’s flow past a deformed sphere: an analytical approach
Autorzy:
Srivastava, D. K.
Yadav, R. R.
Yadav, S.
Powiązania:
https://bibliotekanauki.pl/articles/280226.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
Stokes drag
Oseen’s drag
axially symmetric arbitrary body
axial flow
Opis:
In a recent authors’ paper, the general expression of Stokes drag experienced by a deformed sphere in both longitudinal and transverse flow situations was calculated in terms of the deformation parameter up to the second order. In this paper, Oseen’s correction to the axial Stokes drag on the deformed sphere is presented by using Brenner’s formula in general, first and then applied to prolate and oblate the deformed spheroid up to the second order of the deformation parameter. Numerical values of Oseen’s correction is obtained with respect to the deformation parameter and Reynolds number. The corresponding variations are depicted in figures. Some particular cases of a needle shaped body and flat circular disk are considered and found to be in good agreement with those existing in the literature. The import ant applications are also highlighted.
Źródło:
Journal of Theoretical and Applied Mechanics; 2013, 51, 3; 661-673
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laboratory tests of the aerodynamic drag coefficient of the flag as a body with low stiffness
Autorzy:
Wilk, A.
Skuta, M.
Powiązania:
https://bibliotekanauki.pl/articles/1943232.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska
Tematy:
aerodynamic drag coefficient
flag
Opis:
The shape and drag of bodies with small stiffness may change during the airflow. This problem refers to such bodies as flags, bands, banners, flapping sails as well as blades and cables which vibrate due to the flow. Laboratory tests carried out to point out the aerodynamic drag coefficient of a flag are discussed in this article. The laboratory tests were carried out in an aerodynamic tunnel at different airflow velocities for flags with different dimensions made of fabrics of different roughness and stiffness. The drag coefficient value decreases with the increasing airflow velocity. The drag coefficient is higher for materials with higher roughness. The drag coefficient value is also influenced by the fabric stiffness and kind of edge. Great engineering importance to the stability of a structure (e.g. a flag mast) and the safety of nearby persons and buildings are attached to the analyzed problem.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2009, 13, 1-2; 5-14
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of GPS receiver to road tests of automobile
Autorzy:
Sar, H.
Pokorski, J.
Fundowicz, P.
Reński, A.
Powiązania:
https://bibliotekanauki.pl/articles/242475.pdf
Data publikacji:
2013
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
automobile dynamics
air drag coefficient
rolling drag coefficient
ECE 13 Regulation
road transport
Opis:
The article presents the assessment of the possibilities of applying GPS receiver for the measurement and acquisition of the longitudinal velocity of automobile in the investigations of longitudinal dynamics of automobile. For many years for the measurement of the longitudinal velocity Correvit-L sensors are applied. Major simplification of the measurement of the velocity with the GPS receiver, compared with correlational-optical sensors Correvit-L is giving the possibility to faster prepare the automobile for examinations. The more so as only recently GPS receivers with 10 Hz sampling rate are available. In the paper is shortly described the software specially designed for the measurements that makes it possible to simultaneously measure both the longitudinal velocity signal from GPS receiver and from Correvit-L sensor in real time. Furthermore, the application of the measurement of the velocity is presented on the basis of such road tests as the attempt of accelerating through the following gears, the attempt of free deceleration and the attempt of braking according to ECE 13 Regulation. On the basis of the mentioned manoeuvers the characteristics of the vehicle’s acceleration and dynamic coefficient, rolling and air drag coefficient and the braking deceleration were determined. The paper shows also some problems connected with applying GPS receiver to measure longitudinal velocity of the automobile.
Źródło:
Journal of KONES; 2013, 20, 3; 359-366
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Minimum drag shape bodies moving in inviscid fluid – revisite
Autorzy:
Tesch, K.
Kaczorowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/175420.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
minimum drag
variational calculus
optimisation
Opis:
This paper presents the classic approach to minimum drag shape body problem, moving at hypersonic speeds, leading to famous power law shapes with value of the exponent of 3 4. Twoand three-dimensional cases are considered. Furthermore, an exact pseudo solution is given and its uselessness is discussed. Two new solutions are introduced, namely an approximate solution due to form of the functional and solution by means of optimisation of a Bézier curve. The former transforms the variational problem to the classic problem of function optimisation by assuming certain class of functions, whereas the latter by means of discretised functional.
Źródło:
Transactions of the Institute of Fluid-Flow Machinery; 2017, 135; 73-85
0079-3205
Pojawia się w:
Transactions of the Institute of Fluid-Flow Machinery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Computational study of the wake control problem
Autorzy:
Protas, B.
Powiązania:
https://bibliotekanauki.pl/articles/279533.pdf
Data publikacji:
1999
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
flow control
drag reduction
vortex method
Opis:
In the paper we are concerned with the problem of flow control. We consider two-dimentional (2D) turbulent wake flows past rotating obstacles where the control objective is to minimize the drag force. Results of numerical simulations are presented which indicate that substantial drag reduction can be obtained using an open-loop algorithm. This finding is compared with available experimental data. In the second part of the paper we derive a rigorous feedback method for optimal flow control.
W pracy badany jest problem sterowania przepływem. Rozważanyjest dwuwymiarowy turbulentny opływ obracającej się przeszkody. Celem sterowania jest minimalizacja siły oporu. Przedstawione wyniki stymulacji numerycznych dowodzą, że istotne efekty można uzyskać przy pomocy algorytmów "otwartych". Fakt ten potwierdzają również dostępne dane eksperymentalne. W drugiej części pracy sformułowany jest algorytm sprzężenia zwrotnego oparty o teorię sterowania optymalnego.
Źródło:
Journal of Theoretical and Applied Mechanics; 1999, 1; 13-27
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fluid flow in the impulse valve of a hydraulic ram
Autorzy:
Sobieski, Wojciech
Grygo, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/950067.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
ram pump
drag force
CFD
ANSYS Fluent
Opis:
The paper presents the results of a study investigating the equilibrium of forces acting on the closing element of the impulse valve in a water ram at the end of the acceleration stage. Acceleration is one of the three main stages in the working cycle of a water ram. In the first part of the paper, we estimated water velocity based on our earlier experimental measurements. We also calculated the minimum force required for closing the impulse valve. The second part of the paper discusses two variants of a numerical model, which was developed in ANSYS Fluent to determine the resultant hydrodynamic pressure and, consequently, the forces acting on the head of the impulse valve at the end of the acceleration stage. The main aim of this research was to verify the applicability of numerical modeling in water ram studies. The present study was motivated by the fact that Computational Fluid Dynamics is very rarely applied to water rams. In particular, we have not found any numerical studies related to the equilibrium of forces acting on the closing element of the impulse valve in a water ram.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2019, 22(3); 205-220
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Feeder type optimisation for the plain flow discharge process of an underground hopper by discrete element modelling
Autorzy:
Necas, J.
Hlosta, J.
Zurovec, D.
Zidek, M.
Rozbroj, J.
Zegzulka, J.
Powiązania:
https://bibliotekanauki.pl/articles/101876.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
drag chain conveyor
discrete element method
simulation
Opis:
This paper describes optimisation of a conveyor from an underground hopper intended for a coal transfer station. The original solution was designed with a chain conveyor encountered operational problems that have limited its continuous operation. The Discrete Element Modeling (DEM) was chosen to optimise the transport. DEM simulations allow device design modifications directly in the 3D CAD model, and then the simulation makes it possible to evaluate whether the adjustment was successful. By simulating the initial state of coal extraction using a chain conveyor, trouble spots were identified that caused operational failures. The main problem has been the increased resistance during removal of material from the underground hopper. Revealed resistances against material movement were not considered in the original design at all. In the next step, structural modifications of problematic nodes were made. For example, the following changes have been made: reduction of storage space or installation of passive elements into the interior of the underground hopper. These modifications made were not effective enough, so the type of the conveyor was changed from a drag chain conveyor to a belt conveyor. The simulation of the material extraction using a belt conveyor showed a significant reduction in resistance parameters while maintaining the required transport performance.
Źródło:
Advances in Science and Technology. Research Journal; 2017, 11, 3; 246-252
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental and numerical analysis of vortex generators designed for utility vehicles
Autorzy:
Chidambaram, Ramesh Kumar
Kanna, Rajesh
Gopal, Poomanandan
Arumugam, Senthil Kumar
Powiązania:
https://bibliotekanauki.pl/articles/27312222.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
vortex generator
pressure coefficient
numerical simulation
drag force
Opis:
The main goal of today’s car designers is to minimize fuel consumption in all possible ways at the same time maintaining the vehicle’s performance as usual. The goal of this work is to study the effect of adding a vortex generator (VG) on the aerodynamics of the vehicle and fuel economy. Both theoretical and experimental works were carried out and the outcomes of the numerical simulations are contrasted with those of the experimental results. A utility vehicle model with a scale ratio of 1:15 was used as a test model. Experimental research has been done on the fluctuation of the coefficient of pressure, dynamic pressure, and coefficients of lift and drag with and without VG on the roof of a utility vehicle. The delta-shaped VG was put to the test both numerically and experimentally. At a velocity of 2.42 m/s, it is observed that the addition of VG can raise the pressure coefficient by about 17%. When compared to the vehicle model without vortex generators, the velocity profile of the ccomputational fluid dynamics analysis shows that at the back end of the vehicle, the wake has been minimized with VG.
Źródło:
Archives of Thermodynamics; 2023, 44, 3; 217--240
1231-0956
2083-6023
Pojawia się w:
Archives of Thermodynamics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aerodynamic Research of the Overpressure Device for Individual Transport
Autorzy:
Magryta, P.
Powiązania:
https://bibliotekanauki.pl/articles/118177.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Promocji Wiedzy
Tematy:
aviation propulsion
CFD
3D structure
aerodynamic drag
Opis:
Paper proposes a solution of overpressure device for individual transport, the purpose of which is to accumulate the overpressure in a certain geometric area, through the use of specially designed three-dimensional structures. In order to verify the underlying assumptions of the idea, it was decided to perform a simulation study of air flow stream within the proposed unit. These studies were done in Star CD – Pro Star 3.2 software. Further studies were carried out on the actual real model. The verification was performed to compare and identify the main parameters of air flow through the three-dimensional structure.
Źródło:
Applied Computer Science; 2017, 13, 1; 5-19
1895-3735
Pojawia się w:
Applied Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performative Discourse of Drag Queens: A Sociolinguistic Study
Autorzy:
Szymańska, Maria
Powiązania:
https://bibliotekanauki.pl/articles/1368415.pdf
Data publikacji:
2020-03-30
Wydawca:
Uniwersytet Łódzki. Wydawnictwo Uniwersytetu Łódzkiego
Tematy:
drag queens
discourse
political discourse
language and identity
Opis:
The article presents the analysis of two speeches given by Rory O’Neill, also known as Panti Bliss, who is so far the most recognisable Irish drag queen. Apart from being a drag queen, Rory O’Neill is also a political activist whose performances were part of the campaign before the referendum concerning the 34th Amendment to the Constitution of Ireland. In the analysis both these aspects of the speaker’s identity are taken into consideration. Although the analysis is mostly linguistic, it also considers extralinguistic aspects of communication, e.g. the performer’s appearance on stage, as contextual elements are essential in sociolinguistic contexts. Thus, the analysis draws from the theoretical background focused on political discourse and the language used by drag queens to a detailed account of the two speeches in order discuss them in relation to the standards of both a drag performance and a political speech.
Źródło:
Research in Language; 2020, 18, 1; 15-35
1731-7533
Pojawia się w:
Research in Language
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Właściwości reologiczne wodnych roztworów mieszanin niejonowych i amfoterycznych środków powierzchniowo czynnych
Rheological properties of aqueous solutions of mixtures consisting of nonionic and amphoteric surfactants
Autorzy:
Różański, J.
Powiązania:
https://bibliotekanauki.pl/articles/2072138.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
surfaktanty
reologia
redukcja oporów przepływu
surfactants
rheology
drag reduction
Opis:
W pracy przedstawiono wyniki badań eksperymentalnych nad właściwościami reologicznymi roztworów wodnych mieszaniny dwóch surfaktantów amfoterycznego alkiloamidopropylobetainy (CAPB) i niejonowego dieta- noloamidu kwasów tłuszczowych oleju kokosowego (DEA). Wykazano, że właściwości reologiczne użytych w badaniach mieszanin silnie zależą od stosunku wagowego CAPB/DEA. Pomiary spadku ciśnienia przy przepływie użytych mieszanin surfaktantów w rurze pozwoliły ustalić, że obniżają one opory przepływów turbulentnych.
Rheological properties of aqueous micellar solutions of two surfactant mixtures: cocamidopropyl betaine (CAPB) amphoteric surfactant and dietha- nolamide (DEA) coco fatty acid nonionic surfactant were studied. It was demonstrated that rheological properties of mixtures used were strongly dependent on the weight ratio of CAPB/DEA. The measurements of pressure drop of surfactant mixtures showed that they had the drag reduction ability during turbulent flow.
Źródło:
Inżynieria i Aparatura Chemiczna; 2013, 6; 559--560
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An experimental study of interceptor’s effectiveness on hydrodynamic performance of high-speed planing crafts
Autorzy:
Karimi, M. H.
Seif, M. S.
Abbaspoor, M.
Powiązania:
https://bibliotekanauki.pl/articles/258886.pdf
Data publikacji:
2013
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
interceptors
drag reduction
hydrodynamic quality
planing catamaran
mono-hull
Opis:
Trim control mechanisms such as interceptors and trim flaps have been widely used in recent years in highspeed crafts for ride and trim control. In spite of their extensive application, a few studies investigating the impact of interceptors on planing craft performance, have been published. In the present study, the impact of interceptors on planing crafts hydrodynamic quality is investigated through application of an experimental method. Two scaled-down models of high-speed planing mono-hull and catamaran are tested with and without interceptors in calm water at different heights of the interceptors to investigate the effect of interceptors on drag reduction of the models. The first one is a scaled-down model of 11 m planning mono-hull boat and the test was conducted at the towing tank of Sharif University of Technology, Iran. The second one is a scaled-down model of 18 m planing catamaran boat and the test was conducted at the towing tank of Krylov Shipbuilding Research Institute (KSRI), Russia. The experimental results show a remarkable drag reduction of up to 15% for mono-hull model and up to 12% for catamaran model over the wide speed range of the models.
Źródło:
Polish Maritime Research; 2013, 2; 21-29
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Opory ruchu pociągów metra (5)
Drag resistance of metro trains – empirical equations
Autorzy:
Biliński, Janusz
Błażejewski, Maciej
Malczewska, Marta
Szczepiórkowska, Marta
Powiązania:
https://bibliotekanauki.pl/articles/253481.pdf
Data publikacji:
2020
Wydawca:
Instytut Naukowo-Wydawniczy TTS
Tematy:
opory ruchu
tabor szynowy
metro
drag resistance
rolling stock
Opis:
W artykule przedstawiono zależności empiryczne, opisujące opory ruchu dla wagonów metra. Przedstawiono szereg wzorów, opartych na równaniu Davisa, opisujących opory ruchu pojazdu jako kwadratową funkcję prędkości jazdy. Większość zależności związana jest z masą lub obciążeniem osi pojazdu oraz z oporem aerodynamicznym w czasie ruchu pojazdu. Artykuł stanowi próbę usystematyzowania istniejących zależności, opracowanych przez wielu autorów, które zostały przedstawione w literaturze przedmiotu. Takie zestawienie jest pomocne w inżynierskich obliczeniach szacunkowego zużycia energii, wykorzystywanych zarówno w fazie projektowej pojazdu, jak i w procesie oceny zużycia energii na cele trakcyjne. W artykule omówiono oszacowanie dokładności obliczeń teoretycznych sił oporów ruchu ze wskazaniem na konieczność weryfikacji wyników symulacji z wynikami uzyskanymi w warunkach rzeczywistej eksploatacji.
The article presents empirical formulae, describing the drag resistance of various types of metro trains. It is presented a number of formulas, based on Davis equation, describing the train’s resistance to motion as a square function of driving speed. Most of the equations are related to the mass or axle load of the vehicle and to the aerodynamic resistance during the movement of the vehicle. The article is an attempt to systematize the existing mathematical descriptions of drag resistance, which are presented in the several publications on the subject and were developed by many authors.
Źródło:
TTS Technika Transportu Szynowego; 2020, 3-4; 58-59
1232-3829
2543-5728
Pojawia się w:
TTS Technika Transportu Szynowego
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Experimental study on Ahmed’s body drag coefficient
Autorzy:
Wysocki, Dominik
Szymanek, Arkadiusz
Powiązania:
https://bibliotekanauki.pl/articles/2133935.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
Ahmed body
aerodynamics
wind tunnel
drag coefficient
boundary layer
Opis:
The work presents an experimental designation of the aerodynamic drag coefficient for two configurations of the Ahmed body model, with slant angle of 25° and with the inactive synthetic jet generator. When analyzing the aerodynamic drag of vehicles, most authors focus on higher Reynolds numbers, describing lower values only by designated trend lines. Which is why the main contribution of this experimental work was to designate the Ahmed’s body drag coefficient for low Reynolds numbers and to verify the obtained results with other authors experiments especially with the trend lines for Reynolds number in the range 0,35x105 – 1,8x105. For data taken from the literature, it can be seen that the value of the drag coefficient for the Ahmed body model decreases when the Reynolds number increases. The results obtained during the experiment show the opposite tendency.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2022, 25(1); 87--105
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
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