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CFD Calculations in Turbomachinery and their Validation
Váchová, J. ; Louda, P. ; Příhoda, Jaromír ; Luxa, Martin ; Šimurda, David
Numerical data obtained by 2D compressible flow CFD simulation were validated by the comparison with experimental results. The investigation was made on the mid-section of the 48" long rotor blade and it was focused on the effect of shock-wave interactions with shear layers. This interaction results in the laminar/turbulent transition where separated flow occurs and it has impacts on flow structure and the blade cascade losses. Numerical simulations were carried out by two different codes: the commercial code NUMECA based on the gamma-Re transition model connected with the SST k-epsilon/k-omega turbulence model and in-house code of the Dept. of Technical mathematics, CTU Prague/ Institute of Thermodynamics in Prague. Simulations of the laminar and the fully turbulent flows were accomplished for comparison using the same numerical approach.
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IMPLEMENTATION OF k-k(L)-omega TURBULENCE MODEL FOR COMPRESSIBLE TRANSITIONAL FLOW INTO OPENFOAM
Kožíšek, Martin ; Martinez, J. ; Fürst, J. ; Příhoda, Jaromír ; Doerffer, P.
This paper deals with the results of implementation of k-kL-ω RANS turbulence model for compressible transitional flow into OpenFOAM. This model was firstly proposed by Walters and Leylek (2005) and utilizes the approach of laminar kinetic energy in order to predict transition between laminar and turbulent flows. The capability of laminar/turbulent transition modelling is tested for the basic flat plate test cases and for the VKI turbine cascade. The comparison between new implementation, k-kL-ω for incompressible flow supplied in OpenFOAM and g−Req model from commercial CFD package FINE/Turbo distributed by NUMECA Int. are shown. The properties of the implementation of k-kL-ω model for compressible flow simulations into OpenFOAM are discussed.
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Numerical Solution of 3D Airflow in Channel Representing a Vocal Tract
Pořízková, P. ; Kozel, Karel ; Horáček, Jaromír
This study deals with the numerical solution of a 3D compressible flow of a viscous fluid in a channel for low inlet airfloe velocity. the channel is a simplified model of the glottal space in the human vocal tract. The system of Navier-Stokes equations has been used as mathematical model of laminar flow of the compressible viscous fluid in a domain. The numerical solution is implemented using the finite volume method (FVM)and the predictor-corrector MacCormack scheme with artifical viscosity using a grid of quadrilateral cells.
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Numerical Simulation of Turbulent Flows Through Turbine Cascade With Rough Blades
Fürst, J. ; Louda, Petr ; Příhoda, Jaromír
The article deals with numerical simulation of turbulent compressible flows through 2D model of a turbine with rough blades. The mathematical model is based on the Favre-averaged Navier-Stokes equations combined with several two-equations turbulence models. The wall roughness is modeled using an appropriate boundary condition for specific dissipation rate. The comparison with experimental data shows correct increase of energy losses in the case of increased wall roughness.
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Comparison of measured instantaneous velocities and a calculated flow in an agitated vessel
Kysela, Bohuš ; Pešava, V. ; Konfršt, Jiří ; Chára, Zdeněk ; Kotek, M.
Proces míchání je řízen změnami rychlostního pole a tvorbou vírových struktur v průběhu pracovního cyklu. V této studii porovnáváme výsledky CFD výpočtů s výsledky měření střední prostorově průměrované rychlosti, a také polohově závislé rychlosti odpovídající otáčivému pohybu míchadla, při kterém vznikají vírové struktury. Experimentální data časových řad dvourozměrných vektorových map rychlostí byly získány pomocí TR PIV měření v oblasti míchadla. Pro získání hodnot okamžitých rychlostí a vírových struktur bylo použito modelování pomocí LES v kombinaci s SM simulací pohybu oblasti s míchadlem. Získané výsledky jsou zde porovnány a aplikace použité metody diskutována.
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