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Wyszukujesz frazę "RANS" wg kryterium: Temat


Tytuł:
On the prediction of flow patterns and losses in HP axial turbine stages using 3D RANS solver with two turbulence models
Autorzy:
Lampart, P.
Świrdyczuk, J.
Gardzielewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1955806.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
high-pressureaxial turbine
RANS solver
RANS equations
turbulence modelling
kinetic energy losses
Opis:
An experimentally tested air turbine stage and a real high-pressure (HP) steam turbine stage are calculated using the 3D RANS solver FlowER supplemented with the Baldwin-Lomax and Menter shear stress transport (SST) models. The computations of the model air turbine stage show that the Menter SST model gives better agreement with the experimental data as far as the span-wise distribution of exit velocities and swirl angle. The comparison of performance of the two turbulence models exhibits differences in predicting flow patterns and losses in the considered HP turbine stage. The main differences concern the development of secondary flows and separations. There is a significant span-wise redistribution of losses between these two models. The tendency is that for the same relatively refined grid resolutions, the level of pitch/span averaged losses for the Menter SST turbulence model is slightly above that of Baldwin-Lomax.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 2; 191-206
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some remarks on modelling and simulation of turbulence
Uwagi o modelowaniu i symulacji turbulencji
Autorzy:
Drobniak, S.
Bogusławski, A.
Tyliszczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/281792.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
turbulencja
LES
DNS
turbulence
RANS
Opis:
The paper presents contemporary developments in the field of deterministic description of turbulence with special reference to Large Eddy Simulation (LES) methods. The limitations of conventional turbulence modelling based on stochastic methodology have been discussed, and reasons for development of deterministic approach outlined. It has been shown that the computational power of the fastest available computers restrict possible DNS (Direct Numerical Simulation) solutions to the range of small Reynolds numbers. Finally, basic assumptions have been formulated for the LES formalism that seem to offer a reasonable compromise between the tendency towards the deterministic solution to Navier-Stokes equations and the existing computational resources.
Praca przedstawia współczesny stan wiedzy w dziedzinie numerycznego modelowania turbulencji ze szczególnym uwzględnieniem metody LES (ang. Large Eddy Simulation). Przedstawiono ograniczenia modeli turbulencji typu RANS, opartych o uśrednione w czasie równania Reynoldsa oraz wskazano perspektywy deterministycznego ujęcia turbulencji z użyciem metod DNS (ang. Direct Numerical Simulation). Wykazano również, że możliwości najszybszych dostępnych obecnie komputerów ograniczają możliwe obszary aplikacji DNS do przepływów o stosunkowo niskich liczbach Reynoldsa. Następnie sformułowano podstawowe zależności dla metod LES i wskazano ich perspektywiczne znaczenie dla inżynierskiego modelowania przepływów turbulentnych.
Źródło:
Journal of Theoretical and Applied Mechanics; 2008, 46, 2; 243-256
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Modeling of unsteady turbulent flows in turbomachines
Autorzy:
Magagnato, F.
Powiązania:
https://bibliotekanauki.pl/articles/1967650.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
turbulence
compressible
unsteady
RANS
LES
Opis:
The suitability of existing models for the simulation of flow through turbomachines is investigated and compared with a recently proposed adaptive turbulence model. Discussed are the improvements in accuracy that can be achieved by using non-linear turbulence models and unsteady calculations. The adaptive turbulence model is based on two equation turbulence modeling. It uses the temporal and spatial scales of the flow field to automatically adapt itself to the unresolved turbulent fluctuations. At its asymptotic limits it reduces either to a Direct Numerical Simulation – when the turbulent scales are in the order of the Kolmogorov micro scale – or to a standard two equation model – when the fluctuations are not resolved at all. In order to compare the quality of the presented models two cases have been considered: the flow past a cylinder and a subsonic as well as transonic flow past the VKI turbine blade. Calculations have been performed for each case using all the models and the results have been compared with measurements. The unsteady calculations gave better agreement with the experimental data demonstrating the superiority over steady state calculations for turbomachines.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 477-494
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Niestacjonarne modelowanie fluktuacji przepływu dwufazowego ciecz-ciecz w mieszalniku statycznym typu Kenics
Numerical modeling of two-phase liquid - liquid turbulent flow fluctuations in a static Kenics mixer
Autorzy:
Jaworski, Z.
Murasiewicz, H.
Powiązania:
https://bibliotekanauki.pl/articles/2070030.pdf
Data publikacji:
2009
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
LES
symulacja niestacjonarna RANS
ciecz-ciecz
mieszalnik statyczny Kenics
unsteady RANS
liquid-liquid
static mixer
Opis:
Przedstawiono wyniki modelowania numerycznego przepływu burzliwego dwufazowego w mieszalniku statycznym Kenics. W badaniach CFD wykorzystano dwa podejścia: symulacji wielkowirowych LES z modelem Smagorimiky'ego-Lilly oraz metodę symulacji niestacjonarnych URANS z modelem k-e. Symulacje numeryczne przeprowadzono dla dwóch niemieszających się wzajemnie cieczy: wody i oleju silikonowego oraz dla liczby Re —W 000.
Results of numerical modeling of two-phase turbulent flow in a static Kenics mixer are presented. The CFD simulations were carried out using two approaches: 1) large eddy simulation with the Smago-rinsky-Lilly model and 2) unsteady RANS method with the fe-c model. Water was used as the continuous phase whereas silicon oil formed the dispersed phase. The Reynolds number value was equal to 10000.
Źródło:
Inżynieria i Aparatura Chemiczna; 2009, 1; 98-100
0368-0827
Pojawia się w:
Inżynieria i Aparatura Chemiczna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigating the effect of water depth on ship resistance using RANS CFD method
Autorzy:
Hoa, Nguyen Thi Ngoc
Vu, Bich Ngoc
Tran, Ngoc Tu
Chien, Nguyen Manh
Le, Tat Hien
Powiązania:
https://bibliotekanauki.pl/articles/259677.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ship resistance
shallow water
RANS
Opis:
On inland waterways the ship resistance and propulsive characteristics are strictly related to the depth of the waterway, thus it is important to have an understanding of the influence of water depth on ship hydrodynamic characteristics. Therefore, accurate predictions of hydrodynamic forces in restricted waterways are required and important. The aim of this paper is investigating the capability of the commercial unsteady Reynolds– Averaged Navier–Stokes (RANS) solver to predict the influence of water depth on ship resistance. The volume of fluid method (VOF) is applied to simulate the free surface flow around the ship. The hull resistance in shallow and deep water is compared. The obtained numerical results are validated against related experimental studies available in the literature.
Źródło:
Polish Maritime Research; 2019, 3; 56-64
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of the drag force reduction for homogeneous column of vehicles
Autorzy:
Hamiga, Władysław
Ciesielka, Wojciech
Powiązania:
https://bibliotekanauki.pl/articles/2064420.pdf
Data publikacji:
2019
Wydawca:
STE GROUP
Tematy:
aerodynamics
platooning
RANS
CFD
vehicles
aerodynamika
pluton
pojazdy
Opis:
This paper presents simulation studies on the aerodynamics of vehicles moving in an organized column. The object of research is a column that consist of three vehicles of the same type (homogeneous column). In this research geometry of Ford Transit was used. As a part of the studies, the air drag forces acting on individual vehicles were calculated. The results are presented in dimensionless drag coefficient. The influence of the distance between cars on the generated force was also determined. In the first stage of the work, a numerical model was developed based on the Ahmed body reference structure. The calculations were carried out for 9 different velocities. The obtained results of the drag coefficient were compared with the work of other authors. The applied turbulence model and parameters of the boundary layer were used to create a numerical model of a moving column of vehicles. Mesh independence for numerical model of van was verified. The Finite Volume Method was implemented in the ANSYS Fluent program and used for the calculations. The use of supercomputers was necessary due to the large size of the grid.
Źródło:
New Trends in Production Engineering; 2019, 2, 1; 524--531
2545-2843
Pojawia się w:
New Trends in Production Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study of step forward swept angle effects on the hydrodynamic performance of a planing hull
Autorzy:
Nourghasemi, H.
Bakhtiari, M.
Ghassemi, H.
Powiązania:
https://bibliotekanauki.pl/articles/135251.pdf
Data publikacji:
2017
Wydawca:
Akademia Morska w Szczecinie. Wydawnictwo AMSz
Tematy:
planing hull
step forward swept angle
hydrodynamic performance
drag
wake profile
RANS
Opis:
One of the most effective methods to diminish the drag of a planing craft is to use a step at the bottom of the hull. A stepped hull causes a reduction of the wetted area and, as a result, a decrease in the drag. The step may be designed as a straight line through the entire width of the hull or may be V-shaped with a forward or backward swept angle. In this paper, the effects of the step forward swept angle on the hydrodynamic performance of a hard chine planing vessel are investigated by finite volume method (FVM). Reynolds-Averaged Navier Stokes (RANS) equations with a standard k-ε turbulence model coupled with volume of fluid (VOF) equations are solved in order to simulate a transient turbulent free surface flow around the hull with the help of Ansys CFX software. In order to predict hull motions, equations of rigid body motions for two degrees of freedom (2-DOF) are coupled with fluid flow governing equations. To validate the presented numerical model, first the numerical results are compared with available experimental data, and then the obtained numerical results of the drag, dynamic trim, sinkage, wetted keel length, wetted chine length, pressure distribution on the hull, wetted surface and wake profile at different Froude numbers and step angles are presented and discussed.
Źródło:
Zeszyty Naukowe Akademii Morskiej w Szczecinie; 2017, 51 (123); 35-42
1733-8670
2392-0378
Pojawia się w:
Zeszyty Naukowe Akademii Morskiej w Szczecinie
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical prediction of propeller-hull interaction characteristics using RANS method
Autorzy:
Tu, Tran Ngoc
Luu, Do Duc
Ha, Nguyen Thi Hai
Quynh, Nguyen Thi Thu
Vu, Nguyen Minh
Powiązania:
https://bibliotekanauki.pl/articles/258472.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
propeller
interaction
hull
wake fraction
thrust deduction
relative rotative efficiency
RANS equations
Opis:
The paper presents the results of computational evaluation of the hull-propeller interaction coefficients, also referred to propulsive coefficients, based on the unsteady RANS flow model. To obtain the propulsive coefficients, the ship resistance, the open-water characteristics of the propeller, and the flow past the hull with working propeller were computed. For numerical evaluation of propeller open-water characteristics, the rotating reference frame approach was used, while for self-propulsion simulation, the rigid body motion method was applied. The rotating propeller was modelled with the sliding mesh technique. The dynamic sinkage and trim of the vessel were considered. The free surface effects were included by employing the volume of fluid method (VOF) for multi-phase flows. The self-propulsion point was obtained by performing two runs at constant speed with different revolutions. The well-known Japan Bulk Carrier (JBC) test cases were used to verify and validate the accuracy of the case studies. The solver used in the study was the commercial package Star-CCM+ from SIEMENS.
Źródło:
Polish Maritime Research; 2019, 2; 163-172
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Design analysis of Tesla micro-turbine operating on a low-boiling medium
Autorzy:
Lampart, P.
Kosowski, K.
Piwowarski, M.
Jędrzejewski, Ł.
Powiązania:
https://bibliotekanauki.pl/articles/259365.pdf
Data publikacji:
2009
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
Tesla turbine
axial flow bladed turbine
flow efficiency
CFD calculations
RANS model
Opis:
This paper presents results of the design analysis of a Tesla bladeless turbine intended for a co-generating micro-power plant of heat capacity 20 kW, which operates in an organic Rankine cycle on a low-boiling medium. Numerical calculations of flow in several Tesla turbine models were performed for a range of design parameters. Results of investigations exhibit interesting features in the distribution of flow parameters within the turbine interdisk space. The calculated flow efficiency of the investigated Tesla turbine models show that the best obtained solutions can be competitive as compared with classical small bladed turbines.
Źródło:
Polish Maritime Research; 2009, S 1; 28-33
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
3D multistage computations of turbine flows using different state equations
Autorzy:
Rusanov, A. V.
Yershov, S.
Lampart, P.
Świrdyczuk, J.
Gardzielewicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/1931597.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
3D RANS model
state equation
low pressure steam turbine
Opis:
The paper describes the implementation of a modified state equation for perfect gas and Tammann equation into a 3D RANS solver FlowER. In the modification the specific heats are assumed as linear functions of temperature. A 5-stage LP steam turbine stage is calculated, and the comparison of results for constant and variable specific heats is illustrated. The modification significantly improves the correctness of determination of thermodynamic parameters in the entire flow region, especially in the exit stage.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 4; 591-600
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Feasibility study of RANS in predicting propeller cavitation in behind-hull conditions
Autorzy:
Zhang, Yuxin
Wu, Xiao-ping
Lai, Ming-yan
Zhou, Guo-ping
Zhang, Jie
Powiązania:
https://bibliotekanauki.pl/articles/1573849.pdf
Data publikacji:
2020
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
RANS
Computational Fluid Dynamics (CFD)
propeller cavitation
turbulence model
grid sensitivity
Opis:
The propeller cavitation not only affects the propulsive efficiency of a ship but also can cause vibration and noise. Accurate predictions of propeller cavitation are crucial at the design stage. This paper investigates the feasibility of the Reynolds-averaged Navier–Stokes (RANS) method in predicting propeller cavitation in behind-hull conditions, focusing on four aspects: (i) grid sensitivity; (ii) the time step effect; (iii) the turbulence model effect; and (iv) ability to rank two slightly different propellers. The Schnerr-Sauer model is adopted as the cavitation model. A model test is conducted to validate the numerical results. Good agreement on the cavitation pattern is obtained between the model test and computational fluid dynamics. Two propellers are computed, which have similar geometry but slightly different pitch ratios. The results show that RANS is capable of correctly differentiating the cavitation patterns between the two propellers in terms of the occurrence of face cavitation and the extent of sheet cavitation; moreover, time step size is found to slightly affect sheet cavitation and has a significant impact on the survival of the tip vortex cavitation. It is also observed that grid refinement is crucial for capturing tip vortex cavitation and the two-equation turbulence models used – realizable k-ε and shear stress transport (SST) k-ω – yield similar cavitation results.
Źródło:
Polish Maritime Research; 2020, 4; 26-35
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Unsteady flow simulation in hydraulic machinery
Autorzy:
Ruprecht, A.
Powiązania:
https://bibliotekanauki.pl/articles/1986686.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
unsteady RANS
parallel computing
hydro turbine
rotor-stator interaction
vortex rope
Opis:
In the field of hydraulic machinery Computational Fluid Dynamics (CFD) is routinely used today in research and development as well as in the daily design phase. Today in industry mostly steady state simulations are applied. In this paper, however, an overview of unsteady simulations is shown for different applications. The presented examples contain problems with self excited unsteadiness, vortex rope in the draft tube, as well as applications with externally forced unsteadiness by changing or moving geometries and rotor-stator interactions. For the shown applications the requirements, potential and limitations of unsteady flow analysis are assessed.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 187-208
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study on two dimensional distribution of streamwise velocity in open channel turbulent flows with secondary current effect
Autorzy:
Mohan, S.
Kundu, S.
Ghoshal, K.
Kumar, J.
Powiązania:
https://bibliotekanauki.pl/articles/38616700.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
velocity distribution
open channel flow
turbulent flow
RANS equations
secondary current
finite difference method
Opis:
For studying mechanism of sediment transport in river flows, open channel flow is a prototype. Flow has always three components of velocity for all types of channel geometry and for a time independent uniform flow along streamwise or main flow direction, all the components of velocity are functions of lateral and vertical coordinates. The present study investigates the two dimensional distribution of streamwise (or longitudinal) velocity starting from the Reynolds averaged Navier–Stokes equation for a turbulent open channel flow which is steady and uniform along the main flow direction. Secondary flows both along the vertically upward direction and along the lateral direction are considered which are also taken as functions of lateral and vertical coordinates. Inclusion of the secondary current brings the effect of dip phenomenon in the model. The resulting second order partial differential equation is solved numerically. The model is validated for all the cross-sectional, transverse and centreline velocity distribution by comparing with existing relevant set of experimental data and also with an existing model. Comparison results show good agreement with data as well as with the previous model proving the efficiency of the model. It is found that the transverse velocity distribution depends on the formation of circular vortex in the cross-sectional plane and becomes periodic as the number of circular vortex increases for increasing aspect ratios.
Źródło:
Archives of Mechanics; 2021, 73, 2; 175-200
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study of fuel and turbulence distributions in an automotive-sized scavenged pre-chamber
Autorzy:
Bolla, Michele
Shapiro, Evgeniy
Kotzagianni, Maria
Kyrtatos, Panagiotis
Tiney, Nick
Boulouchos, Konstantinos
Powiązania:
https://bibliotekanauki.pl/articles/133134.pdf
Data publikacji:
2019
Wydawca:
Polskie Towarzystwo Naukowe Silników Spalinowych
Tematy:
scavenged prechamber
Reynolds-averaged Navier-Stokes
RANS
large-eddy simulation
LES
mixture formation
oczyszczona komora wstępna
tworzenie mieszanki
Opis:
This article presents a numerical study of the fuel and turbulence distributions in a pre-chamber at spark-time. The study has been conducted in the framework of the H2020 Gas-On project, dealing with the development of a lean-burn concept for an automotive-sized gas engine equipped with a scavenged pre-chamber. The test case considered studies a 7-hole pre-chamber with circumferentially-tilted orifices mounted on the cylinder head of a rapid compression-expansion machine (RCEM), consistent with the experimental test rig installed at ETH Zurich. An accurate description of turbulence and fuel distributions are key quantities determining the early flame development within the pre-chamber. Both quantities have an influence on the overall combustion characteristics and therefore on the engine performance. For this purpose, computational fluid dynamics (CFD) is employed to complement experimental investigations in terms of data completeness. The performance of the Reynolds-averaged Navier-Stokes (RANS)-based turbulence model is compared with large-eddy simulation (LES) through ensemble averaging of multiple LES realizations, in which the fuel injection rate evolution into the pre-chamber has been perturbed. Overall, RANS results show that the distributions of the turbulent kinetic energy and fuel concentration at spark-time agree well with the LES ensemble-averaged counterparts. This constitutes a prerequisite in view of the combustion phase and the accuracy reported provides further confidence in this regard.
Źródło:
Combustion Engines; 2019, 58, 1; 61-67
2300-9896
2658-1442
Pojawia się w:
Combustion Engines
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carpathian Project jako przykład projektu międzynarodowegoeuropejskiego programu sąsiedztwa INNTERREG IIIB CADSES
Carpatian Project as an Example of a Trans-National Project of the European Neighbourhood Programme Interreg IIIB CADSES
Autorzy:
Kuczyńska, Kinga
Powiązania:
https://bibliotekanauki.pl/articles/447442.pdf
Data publikacji:
2007-06
Wydawca:
Instytut Rozwoju Miast
Tematy:
współpraca międzynarodowa
Karpacki region rozwoju
rozwój zrównoważony
ochrona dziedzictwa naturalnego i kulturowego
rans-national cooperation
Carpathian Development Region
sustainable development
environmental and cultural heritage protection
Opis:
W artykule omówiono cele, zakres przestrzenny i merytoryczny projektu oraz przedstawiono oczekiwane rezultaty.
This paper concentrates on goals, spatial and content-related range of the Project, as well as the expected Project results.
Źródło:
Problemy Rozwoju Miast; 2007, 1-2; 119-123
1733-2435
Pojawia się w:
Problemy Rozwoju Miast
Dostawca treści:
Biblioteka Nauki
Artykuł

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