Temat: computational fluid dynamics - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Flow analysis of hydraulic poppet control valve by means of computional fluid dynamics
Autorzy:: Łazowski, J.
Krasucki, J.
Powiązania:: https://bibliotekanauki.pl/articles/248062.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: poppet control valve
computational fluid dynamics (CFD)
flow characteristics
Opis:: The poppet control valve is one of the most widespread hydraulic components. The paper purpose is the evaluation of flow characteristics of poppet valve by means of a complete numerical analysis. The aim of this analysis is to evaluate the valve fluid dynamic performance, exploiting computational fluid dynamics (CFD) techniques, in order to give the reliable indications needed to define the valve design criteria and avoid expensive experimental tests. The numerical analysis was performed by using the commercial code of CFD, and the numerical results show the complete flow field inside the valve. Axisymmetric as well as three-dimensional valve model was considered and the simulation results also are verified with experimental results. The results have confirmed the good accuracy of the simplified CFD analysis based on 2D axisymmetric valve model being more efficient than full 3D approach and show this method as very useful to forecast flow characteristics of poppet control valves. Hydraulic control poppet valve, distribution of the velocity in layers of the fluid, computational grid in the modelled geometry, pressure distribution for axisymmetric and three-dimensional mode for different flow rate, fluid velocity distribution in valve metering section for axisymmetric and three-dimensional model for different flow rates, the example of streamlines, the comparison of flow characteristics are contained in the publication.
Źródło:: Journal of KONES; 2012, 19, 1; 251-259
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: CFD analysis of the influence of flaps extension on the aerodynamic characteristics of the M-28 Bryza aircraft
Autorzy:: Szczepaniak, R.
Konopka, B.
Zahorski, T.
Bąbel, R.
Stryczniewicz, W.
Powiązania:: https://bibliotekanauki.pl/articles/243831.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: M-28 Bryza
aerodynamic characteristics
flap
Computational Fluid Dynamics
Opis:: The paper presents a modelling procedure of the M-28 Bryza wing with extended flaps and Computational Fluid Dynamics (CFD) simulations results preformed in order to assess the performance of the investigated wing for various flap extension rates. The M-28 Bryza is a two-engine high-wing aircraft used in the Polish Air Force for short distance airlift of people and equipment. The aim of this work was to determine the aerodynamic characteristics of the investigated wing. The CFD simulations were performed in order to investigate the influence of flap extension on lift and drag coefficients at various angles of attack. In order to validate the results of two different commercial CFD packages were used. The findings are presented in the form of flow visualization and aerodynamic characteristics. The typical and non-standard extension rates were investigated for low, moderate and high angles of attack. The results correlated with the limitations specified in the aircraft manual. The outcome of the presented work confirmed the feasibility of the presented methodology for its use as a supportive tool for providing additional information about airplane performance in standard and non-standard conditions of flight such as landing with one engine working. The results of work might prove useful for M-28 Bryza pilots and maintenance personnel as well as for educational purposes.
Źródło:: Journal of KONES; 2016, 23, 1; 353-360
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Jet and droplet breakup modelling approaches
Autorzy:: Kapusta, Ł. J.
Jaworski, P.
Kowalski, J.
Powiązania:: https://bibliotekanauki.pl/articles/245813.pdf
Data publikacji:: 2015
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: spray
modelling
simulation
breakup
injection
CFD
computational fluid dynamics (CFD)
Opis:: Three-dimensional computational fluid dynamics (CFD) plays important role in engines development. The mixture formation in a direct-injection piston engines poses a huge challenge in successful simulations of the engine processes. It is due to the fact that the spray as a two-phase flow complicates the computational process. Moreover, this multiphase flow is not uniform. Three main zones, depending on the distance from the nozzle exit are visible when a liquid is injected. Very dense so called “thick” in a direct vicinity of the injector hole, than “thin” as a result of pri-mary breakup downstream the injector and finally in the certain distance from the injector appears “very thin” region as a result of secondary breakup. It is important to take into account that the liquid phase in various regimes behaves differently and is under influence of different phenomena. The modelling approach needs to take in to consideration all those elements. This paper focuses on presentation of the theory and numerical models for primary and secondary breakup phenomena. The primary breakup is a process that results from a combination of three mechanisms: turbu-lence within liquid phase, implosion of cavitation’s bubbles and aerodynamic forces acting on a liquid jet. Secondary breakup regime occurs mainly due to the aerodynamic interactions between the liquid and the gaseous phase.
Źródło:: Journal of KONES; 2015, 22, 3; 83-90
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

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: 5.

Tytuł:: Application of the rans flow model for the analysis of the motion of floating objects in waves
Autorzy:: Kraskowski, M.
Powiązania:: https://bibliotekanauki.pl/articles/248052.pdf
Data publikacji:: 2012
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational fluid dynamics (CFD)
ship
drilling platform
mooring
model tests
Opis:: The present paper describes a proposal of the method for simulating the motion of freely floating and moored objects in waves, based on the RANS (Reynolds Averaged Navier-Stokes Equations) flow model. Attempts on using this model for simulating the floating body dynamic started quite recently due to its large requirements for the computer power. Only in the past few years such analyses became more common, however, no unique approach can be observed due to large variety of existing possibilities, numerical methods etc. The paper includes the description of the proposed method, which consists in mesh generation technique, efficient wave generation method, and the mooring system module, as well as two samples of marine applications: analyses of the motion of fishing vessel in head waves and the motion of moored semi-submersible drilling platform. The results were verified basing on the towing tank experiments, conducted by Centrum Techniki Okrętowej (Ship Design and Research Centre) S.A. Generating the waves by prescribed wave motion on both ends of the domain, generating the waves by prescribed wave motion and suppressing them in the damping zone, sliding mesh example, mooring system scheme, forcedisplacement characteristics of the mooring chain, fishing vessel in head waves, heave motion history, outline of the semi-submersible are presented.
Źródło:: Journal of KONES; 2012, 19, 1; 199-206
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Three - dimensional numerical simulations of the combustion chamber of the rotating detonation engine
Autorzy:: Folusiak, M.
Swiderski, K.
Kobiera, A.
Lukasik, B.
Wolanski, P.
Powiązania:: https://bibliotekanauki.pl/articles/245644.pdf
Data publikacji:: 2013
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: rotating detonation engine (RDE)
RDE
computational fluid dynamics (CFD)
CFD
REFLOPS
Opis:: From 2010 Warsaw University of Technology (WUT) and Institute of Aviation (IoA) jointly implement the project under the Innovative Economy Operational Programme entitled ‘Turbine engine with detonation combustion chamber’. The goal of the project is to replace the combustion chamber of turboshaft engine GTD-350 with an annular detonation chamber. During the project, the numerical group that aims to develop computer code allowing researchers to simulate investigated processes has been established. Simulations provide wide range of parameters that are hardly available from experimental results and enable better understanding of investigated processes. Simulations may be also considered as a cheap alternative for experiments, especially when testing geometrical optimizations. In this paper the analysis of simulation results of the combustion chamber of the Rotating Detonation Engine (RDE) investigated at the IoA in Warsaw is presented. Primarily, REFLOPS USG which has become a fundamental numerical tool in the research of the RDE at the IoA is briefly described and governing equations and numerical methods used are shortly presented. Some aspects of numerical simulations of the RDE, related to selection of combustion mechanism, and an initiation of rotating detonation are provided. Secondly, results of simulations of inviscid gas with numerical injectors of hydrogen are compared with available experimental results. Three different wave patterns are identified in numerical solution and briefly described. Results of simulations are compared to experimental results in combustion chamber. Results presented in this paper are part of the project UDA-POIG.01.03.01-14-071 ‘Turbine engine with detonation combustion chamber’ supported by EU and Ministry of Regional Development, Poland.
Źródło:: Journal of KONES; 2013, 20, 1; 83-88
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Computational design and optimisation of innovative, high-efficiency wind turbine
Autorzy:: Stalewski, W.
Zalewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/246604.pdf
Data publikacji:: 2015
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: green power
wind turbine
computational fluid dynamics (CFD)
computer-aided design
optimisation
Opis:: New concept of innovative, high-efficiency wind turbine has been developed and optimised. The turbine consists of a rotor with a vertical axis of rotation and a ring-palisade casing, which task is to deflect wind stream so that it flows perpendicularly to the rotor plane. The main advantage of such configuration of a wind turbine is that due to the vertical axis of symmetry, it works independently on the wind direction and it does not need any mechanism directing it towards the wind. The greatest challenge when designing the turbine was to minimise losses of energy of the wind stream deflected by 90 degrees by the ring vanes of the casing. This involved optimisation of number, shapes and mutual positions of the ring vanes. The whole optimisation works were done based on computational methods of Computer-Aided Design and Optimisation and Computational Fluid Dynamic. Subsequent variants of the ring-palisade casing were designed using an appropriately adapted in-house-software package supporting design and optimisation of multi-element airfoils. Three-dimensional analysis of flow around and inside the casing was conducted by application of commercial URANS solver ANSYS FLUENT. Eventually designed turbine is characterised by high efficiency in respect of acceleration of the wind stream. On the basis of computer simulations, it is estimated that the average velocity of air stream flowing through the rotor plane may be higher than the wind speed by about 45%. Extent of the acceleration of the wind stream partially depends on the number of ring vanes comprising a casing. Depending on specificity of application, this number of ring vanes may be chosen by a compromise between performance and dimensions of the turbine. The proposed wind turbine seems to be very promising solution, especially within the area of small and moderate renewable-energy sources, which in particular may be placed directly in residential-building areas, e.g. on the roofs of houses. This type of renewable-energy sources may also be successfully used in the field of environmentally friendly transport, in the process of producing hydrogen as fuel for fuel cell vehicles.
Źródło:: Journal of KONES; 2015, 22, 2; 221-232
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Virtual ship’s roll decay test with the use of CFD technique
Autorzy:: Krata, P.
Jachowski, J.
Powiązania:: https://bibliotekanauki.pl/articles/243570.pdf
Data publikacji:: 2016
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: sea transport
ship stability
roll simulation
roll decay test
computational fluid dynamics
Opis:: Since safety of navigation is related to the stability performance of a ship, the transverse stability is routinely calculated and measured. One of the crucial experimental approach is a roll decay test. Although, an obtained result of the roll decay test carried out on the full-scale ship needs to be compared to a benchmark enabling an estimation of the relevant stability. Nowadays such a benchmark is just based on the simplified GM-based IMO-recommended formula. This research aims at the more sophisticated method of ship’s natural period of roll estimation and thus her stability assessment. The CFD (computational fluid dynamics) technique is applied and the result of the free roll simulation is compared to the solution of a roll equation. The one degree-of-freedom roll equation is applied with regard to the nonlinear ship righting moment and the nonlinear damping moment obtained according to Ikeda’s method. The six degrees-of-freedom simulation of ship’s roll decay test was carried out by the use of FlowVision code utilizing the Reynolds-averaged Navier–Stokes equation with regard to the turbulent flows based on the eddy viscosity concept. The semi-empirical k-ε turbulence model was applied. Thereby, the CFD-based approach allows to get rid of any assumptions regarding the value of the damping coefficient, which is an advantage over the roll equation based approach.
Źródło:: Journal of KONES; 2016, 23, 2; 215-221
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Simulation of rime icing and its effects on aerodynamic characteristics of an airfoil
Autorzy:: Sznajder, J.
Powiązania:: https://bibliotekanauki.pl/articles/243475.pdf
Data publikacji:: 2018
Wydawca:: Instytut Techniczny Wojsk Lotniczych
Tematy:: computational fluid dynamics
aerodynamics
two-phase flow
simulation of ice accretion
heat exchange
aircraft engineering
transport
vehicle
Opis:: 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.
Źródło:: Journal of KONES; 2018, 25, 3; 437-443
1231-4005
2354-0133
Pojawia się w:: Journal of KONES
Dostawca treści:: Biblioteka Nauki

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