Temat: vortex flow - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: A note on discrete descriptions of water flows in material variables
Autorzy:: Szmidt, K.
Powiązania:: https://bibliotekanauki.pl/articles/241055.pdf
Data publikacji:: 2005
Wydawca:: Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:: potential motion
vortex flow
material variables
discrete integration
Opis:: The paper describes the problem of discrete formulation of plane fluid flows in material description. The investigation is confined to chosen cases of stationary potential and vortex motion of an incompressible inviscid fluid within circular domains with perfect boundaries. The paths of fluid particles are obtained by numerical integration of momentum equations within a discrete time space. Brownian type random disturbances are attached to the displacement field obtained by the integration. It has been shown, that the discrete formulation may lead to solutions in which a small distance between two material points may grow to a relatively large value after a finite elapse of time. The last feature of the procedure may be a serious drawback of the discrete formulation in the material variables.
Źródło:: Archives of Hydro-Engineering and Environmental Mechanics; 2005, 52, 2; 163-175
1231-3726
Pojawia się w:: Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: A Novel Design of a Counter-flow Vortex Tube by Suitable Automation at Hot and Cold Ends
Autorzy:: Macha, D.
Renganathan, M.
Arockiadoss, A. S.
Powiązania:: https://bibliotekanauki.pl/articles/950970.pdf
Data publikacji:: 2016
Wydawca:: Sieć Badawcza Łukasiewicz - Przemysłowy Instytut Automatyki i Pomiarów
Tematy:: counter-flow vortex tube
temperature separation
automation
orifice area controller
blockage cone
Opis:: Separating the cold and hot air by using the principles of the vortex tube can be applied to industrial applications such as cooling equipment in CNC machines, heating processes, cooling suits, refrigerators etc. The vortex tube is well-suited for these applications because it is simple with no moving parts, quiet, compact, and does not use refrigerants. This study is devoted to the development and testing of an automated vortex tube that can meet the demands of time variant applications such as spot cooling during welding. This is achieved with the help of a moving blockage cone at hot end and orifice area controller at cold end. The performance of a counter-flow vortex tube is validated by comparing the results obtained from the present work with the literature.
Źródło:: Journal of Automation Mobile Robotics and Intelligent Systems; 2016, 10, 3; 34-37
1897-8649
2080-2145
Pojawia się w:: Journal of Automation Mobile Robotics and Intelligent Systems
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Model of Pressure Distribution in Vortex Flow Controls
Autorzy:: Mielczarek, S.
Sawicki, J. M.
Powiązania:: https://bibliotekanauki.pl/articles/241160.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:: rotational flow
flow control
vortex valve
storm wastewaters
Opis:: Vortex valves belong to the category of hydrodynamic flow controls. They are important and theoretically interesting devices, so complex from hydraulic point of view, that probably for this reason none rational concept of their operation has been proposed so far. In consequence, functioning of vortex valves is described by CFD-methods (computer-aided simulation of technical objects) or by means of simple empirical relations (using discharge coefficient or hydraulic loss coefficient). Such rational model of the considered device is proposed in the paper. It has a simple algebraic form, but is well grounded physically. The basic quantitative relationship, which describes the valve operation, i.e. dependence between the flow discharge and the circumferential pressure head, caused by the rotation, has been verified empirically. Conformity between calculated and measured parameters of the device allows for acceptation of the proposed concept.
Źródło:: Archives of Hydro-Engineering and Environmental Mechanics; 2015, 62, 1-2; 41-52
1231-3726
Pojawia się w:: Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Measurement of air-water oxygen transfer of cylindrical vortex flow regulators at a recirculating system
Autorzy:: Wójtowicz, P.
Szlachta, M.
Kotowski, A.
Powiązania:: https://bibliotekanauki.pl/articles/208207.pdf
Data publikacji:: 2013
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: hydrodynamics
storms
vortex flow
aeration efficiencies
hydrodynamic flows
oxygen mass transfer
oxygen transfer rate
recirculating system
stormwater systems
sewerage
oxygen
hydrodynamika
burze
wiry
efektywność napowietrzania
przepływy hydrodynamiczne
przenoszenia masy tlenu
szybkość transferu tlenu
system recyrkulacji
systemy deszczowe
kanalizacja
napowietrzanie
Opis:: Hydrodynamic flow regulators are used for diversion and/or limiting excess discharge in wastewater and stormwater systems as a replacement for traditional flow throttling devices. They are highly efficient, reliable and free from common disadvantages of traditional devices. Recent research of the authors indicated that atomization of a liquid by vortex flow regulators accelerates oxygenation and prevents the putrefaction process in wastewater and storm water collection systems. The study presents experimental results of the oxygen transfer measurements for basic designs of cylindrical hydrodynamic flow regulators in a closed-circuit experimental setup at the semi-commercial scale. The oxygen mass transfer coefficient, standard oxygen transfer rate and standard aeration efficiency were determined for the range of tested configurations by the clean water test.
Źródło:: Environment Protection Engineering; 2013, 39, 3; 207-215
0324-8828
Pojawia się w:: Environment Protection Engineering
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

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

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Skocz do pozycji: 6.

Tytuł:: Experimental study on suppression of vortex street behind perforated square cylinder
Autorzy:: Teimourian, A.
Hacışevki, H.
Bahrami, A.
Powiązania:: https://bibliotekanauki.pl/articles/279942.pdf
Data publikacji:: 2017
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: vortex shedding
flow control
coherent flow structure
perforated square cylinder
Opis:: In this study, the effects of entrainment of a fluid through a perforated surface on suppression of the vortex street behind a perforated square cylinder have been studied experimentally. The wake region has been investigated in terms of coherent flow structure, time averaged properties and effectiveness of different perforations. The quantitative measurements revealed that the perforated surfaces are only effective within a width interval of y/D = ±1.0. It has been observed that in the near wake region up to approximately 1.5D downstream the wake, the shedding phenomenon has been suppressed significantly. It has been also demonstrated that velocity profiles and flow structure have been affected by different perforated surfaces and, as a result, coherent structures have been diminished considerably.
Źródło:: Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1397-1408
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Vortex in cell method for exterior problems
Metoda cząstek wirowych dla zagadnień zewnętrznych
Autorzy:: Kudela, H.
Kozłowski, T.
Powiązania:: https://bibliotekanauki.pl/articles/279735.pdf
Data publikacji:: 2009
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: vortex method
flow past cylinder
external problem
Opis:: The ”vortex in cell” method was used to model the flow past a solid body. Problems connected with flows past a body belong to the category of exterior problems. The main difficulty here is to establish the boundary condition far from the body, to solve equations of motion on the numerical mesh. The mesh requires a limited calculation area and the boundary condition far from the body. A method of obtaining the accurate boundary condition in such flows was presented. Testing calculations were performed for the flow past a cylinder for a wide range of Reynolds numbers. The flow past an ellipse was also performed. A good agreement with experimental results and calculations of other researchers was obtained.
Do obliczeń zastosowano metodę cząstek wirowych typu „wir w komórce”. Rzeczywisty obszar przepływu transformowano używając odwzorowania konforemnego. Opisano sposób wyznaczania zewnętrznego warunku brzegowego daleko od ciała, wykorzystując asymptotyczne własności rozwiązania równania Laplace’a. Wyniki numeryczne przedstawiono dla opływu walca w szerokim przedziale liczb Reynoldsa (550 < Re > 9500) oraz cienkiej elipsy. Obliczenia porównano z danymi eksperymentalnymi i wynikami numerycznymi innych badaczy, uzyskując bardzo dobrą zgodność.
Źródło:: Journal of Theoretical and Applied Mechanics; 2009, 47, 4; 779-796
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Random Vortex Method approach to axisymmetric jet in a large tank
Autorzy:: Hedar, I.M.
Styczek, A.
Powiązania:: https://bibliotekanauki.pl/articles/279559.pdf
Data publikacji:: 1999
Wydawca:: Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:: viscous jet flow
stochastic method
axisymmetric vortex blob
Opis:: In the paper we give an extention of the Vortex Blob Method to cover axisymmetric flows of of viscous liquid. We also present a simple simulation of a jet flowing into a half-space large tank. This example shows that the method works and that a more reliable numerical simulation can be performed.
W pracy podano rozszerzenie metody "Vortex Blob" na ruch osiowosymetryczny i przedstawiono symulację strugi płynu lepkiego wpływającego do półograniczonego obszaru. Przykład pokazuje możliwości, choć nie jest wyliczony perfekcyjnie.
Źródło:: Journal of Theoretical and Applied Mechanics; 1999, 4; 863-872
1429-2955
Pojawia się w:: Journal of Theoretical and Applied Mechanics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

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

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Skocz do pozycji: 10.

Tytuł:: Numerical analysis of the tip vortex in an air-conditioners propeller fan
Autorzy:: Wang, J.
Wu, K.
Powiązania:: https://bibliotekanauki.pl/articles/1955218.pdf
Data publikacji:: 2006
Wydawca:: Politechnika Gdańska
Tematy:: tip vortex
internal flow field
propeller fan
numerical simulation
Opis:: A steady, incompressible, turbulent flow field inside a propeller fan used in an air conditioner has been analyzed numerically using the single-equation Spalart-Allmaras turbulence model. It has been found that the formation of tip vortex starts from the blade tip's suction side at about one third of the axial chord's length aft of the rotor's leading edge. It is due to the rolling-up of the intense shear layer flow between the main axial flow and the suck-in inward flow caused by the large pressure difference between the pressure and the suction sides. The tip vortex passes through the blade passage in a curve reversed towards the direction of the blade's rotation. Its trace is partial to the tangential direction as it goes into the aft part of the blade passage covered by the shroud and, simultaneously, its trace in the radial direction is turned from the outward direction to the inward direction. The operating flow rates have an important effect on the axial position of the tip vor-tex's trace, while its effect on the radial position is negligible. At law flow rates, the vortex disappears at a location closer to the leading edge. The effect of the shroud's width on the tip vortex's trajectory is notable. For a fan with a wide shroud, the trace of the tip vortex moves upstream with a smaller radial influence region than that of a fan with a narrower shroud.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2006, 10, 2; 101-112
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: What is the role of the stagnation region in Karman vortex shedding?
Autorzy:: Pankanin, G. L.
Powiązania:: https://bibliotekanauki.pl/articles/221765.pdf
Data publikacji:: 2011
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: flow measurement
Karman vortex shedding
bluff body
stagnation region
Opis:: This paper is devoted to the problem of the appearance of a stagnation region during Karman vortex shedding. This particular phenomenon has been addressed by G. Birkhoff in his model of vortices generation. Experimental results obtained by various research methods confirm the existence of a stagnation region. The properties of this stagnation region have been described based on experimental findings involving flow visualisation and hot-wire anemometry. Special attention has been paid to the relationship between the existence of a slit in the bluff body and the size of the stagnation region. The slit takes over the role of the stagnation region as an information channel for generating vortices.
Źródło:: Metrology and Measurement Systems; 2011, 18, 3; 361-370
0860-8229
Pojawia się w:: Metrology and Measurement Systems
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: Diagnozowanie wentylatora promieniowego w warunkach zmian wartości ciśnienia przepływu gazu
A radial ventilator diagnostic in the conditions of gas flow pressure changings
Autorzy:: Zachwieja, J.
Jarzyna, T.
Powiązania:: https://bibliotekanauki.pl/articles/329202.pdf
Data publikacji:: 2007
Wydawca:: Polska Akademia Nauk. Polskie Towarzystwo Diagnostyki Technicznej PAN
Tematy:: oderwanie strumienia
ścieżka wirowa
separation of flow
vortex path
Opis:: W pracy analizowany jest wpływu spiętrzenia przepływającego czynnika na poziom drgań wentylatora promieniowego. Wyniki uzyskane w warunkach laboratoryjnych zestawiono z rezultatami badań wentylatora przemysłowego. Dane doświadczalne uzupełniono symulacjami numerycznymi przepływu powietrza w kanale między łopatkami wirnika.
This paper presents results of vibration investigation of an industrial ventilator. threats of vibration occurrence resulting from the compressible medium flow parameters through the ventilator chamber were analyzed in detail. There have been presented measurement results taken during an industrial fan operation. Next results of tests performed in a laboratory on a smaller fan with provision of similar working conditions have been presented. Experimental tests were completed with computer simulations during which current lines, pressure and velocity distributions in the channel between the rotor blades were tested.
Źródło:: Diagnostyka; 2007, 3(43); 119-124
1641-6414
2449-5220
Pojawia się w:: Diagnostyka
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 13.

Tytuł:: Study on the effect of the descent rate of a helicopter in the Vortex Ring conditions
Autorzy:: Surmacz, K.
Kowaleczko, G.
Powiązania:: https://bibliotekanauki.pl/articles/248016.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: Vortex Ring State
helicopter descent
computational fluid dynamics
flow simulations
Opis:: One of the limiting factors for a helicopter operation is the Vortex Ring State (VRS). This aerodynamic phenomenon, known as the VRS or “Settling with Power”, is characterized by the formation of circulating air stream moving along a ring shaped track around the main rotor of a helicopter. Conditions, conducive to development of the vortex ring state, occur in the vertical or nearly vertical descent. This leads to decrease in thrust and thus rapidly increasing the rate of descent. This phenomenon occurs for an appropriate combination of induced velocity and the velocity of the stream of airflow from the bottom to the rotor. The rates of change of velocities delimit dangerous areas of flight. The objective of this work was to investigate the influence of the descent rate of a helicopter on the vortex ring formation process and determinants of the occurrence of vortex rings. For better understanding of the nature of this state, a computational method was applied. Series of three-dimensional (3D) unsteady analysis was carried out using Computational Fluid Dynamics tools (CFD). Simulations were realized using geometry and performance of the W-3 “Sokol” helicopter. The paper presents results of a helicopter operation in axial and non-axial descent conditions. Three calculation cases of vertical flight of a helicopter with different rates of velocity changes were considered. A simulation of non-axial descent was based on the measured flight test data for the W-3 helicopter. The results provide information about the changing nature of the flow in the course of the movement of a helicopter and show the influence of the rate of descent during initiation on the development of VRS. Results of the calculations provide guidelines for helicopter pilots.
Źródło:: Journal of KONES; 2016, 23, 1; 345-352
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 14.

Tytuł:: Numerical simulation and modification of 3D flow phenomena in an axial flow fan
Autorzy:: Elhadi, E. E.
Keqi, W.
Powiązania:: https://bibliotekanauki.pl/articles/1954658.pdf
Data publikacji:: 2003
Wydawca:: Politechnika Gdańska
Tematy:: axial flow fan
vortex
stagger angle
numerical simulation
3D
Opis:: This work aims to study and analyze the behavior of flow in an axial flow fan using numerical simulation based on solving Reynolds-averaged Navier-Stokes equations coupled with a modified Spalart-Allaras turbulence model. In the present work, different flow phenomena occuring in an axial flow fan were presented and interpreted at different design conditions and at different regions, with special concern to the rotor exit and stator regions. Large vortices and reverse flow at the stator suction side were observed under high loading conditions. These are mainly due to radial and centrifugal effects in the fluid due to a decreasing flow rate. To avoid this type of flow, the stator flow pattern has been modified using a new stator blade. This blade was designed by changing the stator stagger angle by 10o in the radial direction. This study indicates that the flow in the modified stator region behaves well and gives better performance than that obtained when using a baseline stator, especially under high loading conditions. This study also indicates that the stator stagger angle has a significant effect on modifying the fan performance.
Źródło:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 2; 199-213
1428-6394
Pojawia się w:: TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 15.

Tytuł:: Random vortex method in numerical analysis of 2D flow around circular cylinder
Autorzy:: Kostecki, S.
Powiązania:: https://bibliotekanauki.pl/articles/178682.pdf
Data publikacji:: 2014
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: vorticity
vortex method
flow instability
circular cylinder
boundary element method
Opis:: A combination of the vortex method and the boundary element method is used here to predict the two-dimensional flow field around a circular cylinder. Cylindrical structures experience strong hydrodynamic loading, due to vortex detachment from the both sides of cylinder during the flow. Thus, the practical meaning of such calculation is significant particularly in offshore oil and gas engineering as well as in the bridge and hydraulic structure engineering. This paper presents the mathematical formulation of the vortex method for the velocity and vorticity field calculation. The calculated velocity and vorticity fields are then used to predict the pressure distribution on the cylinder surface by the boundary element method. The resulting pressure on the cylinder, the Strouhal number and the length of the base recirculation zone are compared with solutions of other numerical methods and experiments, and a good agreement is achieved.
Źródło:: Studia Geotechnica et Mechanica; 2014, 36, 4; 57-63
0137-6365
2083-831X
Pojawia się w:: Studia Geotechnica et Mechanica
Dostawca treści:: Biblioteka Nauki

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