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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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Modelování proudění ve špičkové turbinové lopatkové mříži se supersonickým vstupem
Straka, P. ; Stodůlka, J. ; Příhoda, Jaromír
Příspěvek se zabývá numerickou simulací stlačitelného proudění ve špičkové turbinové lopatkové mříži TGR-U-4 se supersonickými vstupními podmínkami. Výpočet je proveden jednak pomocí vlastního numerického programu s explicitním algebraickým modelem Reynoldsových napětí doplněným algebraickým modelem zkráceného přechodu a jednak pomocí SST modelu turbulence s gama-Re modelu přechodu implementovaného v komerčním programu Fluent. Získané výsledky jsou porovnány a diskutovány.
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Notes to Aerodynamic Testing of Supersonic Blade Cascades
Šimurda, David ; Luxa, Martin ; Šafařík, Pavel
Relatively narrow space for aerodynamic design of long rotor blades applied at last stages of large output steam turbines often results in blades with tips operating at supersonic regimes. This brings number of problems. Main of these are additional sources of loss and rather thin border between sections operating under turbine and compressor regimes one adding to performance and the other deteriorating it. Therefore, aerodynamic cascade data on turbine blading for a range of supersonic inlet and outlet conditions are needed. However, ensuring specified supersonic conditions in a high-speed wind tunnel for blade cascade tests is not an easy task and thus it deserves attention.
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Numerical and Experimental Studies of The Flow Through Narrow GAP
Hála, Jindřich ; Luxa, Martin
The flow in channels with characteristic dimension of the order of millimetres is of high importance for determination of losses of the devices such as small turbines, screw-type compressors and for investigation of the tip leakage flow. Since most of the contemporary studies deal with the micro or nano flows, the purpose of this work is to provide a reliable experimental data and to explore the possibilities of the numerical simulations of the present flow
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Modelling of compressible flow through turbine blade cascade with various wall roughness
Příhoda, Jaromír ; Straka, P.
The contribution deals with the numerical simulation of 2D compressible flow through a turbine cascade with smooth and rough blades using the EARSM turbulence model of Hellsten. Predictions were carried out at the Reynolds number Re2is = 850000 for various Mach numbers. The algebraic bypass transition model was applied for comparison in case of smooth blades. Predicted values of the loss coefficient and the flow outlet angle were compared with experimental data for the turbine cascade VS33 with smooth and rough blades of wall roughness.
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