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Modification of the Algebraic Transition Model for Wall Roughness Effect Including a Rough Strip
Straka, P. ; Příhoda, Jaromír
The contribution deals with the simulation of the laminar/turbulent transition on a rough wall. The algebraic transition model taking into account wall roughness according to Straka and Příhoda [8] was further extended for the effect of short rough strip near the leading edge. The proposed correlation was tested by means of incompressible flow over a flat plate covered by sand paper and around the NACA 0012 airfoil with a rough strip near the leading edge. The agreement with experiments is appropriate nevertheless the applicability of the correlation is limited due to the lack of relevant experimental results.
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Effect of Various Boundary Conditions on the Supersonic Flow Through the Tip-Section Turbine Blade Cascade with a Flat Profile
Musil, Josef ; Příhoda, Jaromír ; Fürst, J.
The paper deals with the numerical simulation of 2D compressible flow though the tip-section turbine blade cascade with a flat profile. The OpenFOAM code was used for simulations based on the Favre-averaged Navier-Stokes equations completed by the two-equation SST turbulence model and the gama-Re_th transition model proposed by Langtry and Menter (2009). Calculations were carried out for two nominal regimes with the inlet Mach number M1 = 1.2 and isentropic outlet Mach numbers M2is = 1.7 and 1.9. Simulations of compressible flow with the supersonic inlet were focused on the relation between of the inlet Mach number and the inlet angle given by the unique incidence rule. Further, the effect of the inlet free-stream turbulence and of the outlet isentropic Mach number on the flow filed in the blade cascade was investigated. Numerical results were compared with results of optical and pressure measurements.
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Simulation of Supersonic Flow Through the Tip-Section Turbine Blade Cascade with a Flat Profile
Musil, Josef ; Příhoda, Jaromír ; Fürst, J.
The contribution presents results of the numerical simulation of 2D compressible flow through the tip-section turbine blade cascade with a flat profile and the supersonic inlet. The simulation was carried out by the OpenFOAM code using the Favre-averaged NavierStokes equations completed by the two-equation SST turbulence model and the γ-Reθ bypass transition model. Predictions carried out for nominal conditions were focused particularly on the relation between the inlet flow angle and the inlet Mach number. Further, the effect of the shock-wave/boundary layer interaction on the skin friction coefficient was investigated. Numerical results were compared with experimental data.
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Simulation of Transonic Flow Through a Mid-span Turbine Blade Cascade for Various Mach Numbers
Straka, P. ; Příhoda, Jaromír ; Fenderl, D.
The contribution deals with the numerical simulation of 2D transonic flow through a mid-span turbine blade cascade for several Mach numbers by means of the EARSM turbulence model of Hellsten (2004) connected with the algebraic bypass transition model of Straka and Příhoda (2014). Both models are implemented into an in-house numerical code based on the finite volume method. The gamma-transition model of Menter et al. (2015) with SST turbulence model accessible in the commercial code ANSYS Fluent was used for the comparison.
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Modelling of Flow in Linear Blade Cascade with Thick Trailing Edge at a Lower Reynolds Number
Straka, P. ; Příhoda, Jaromír
In the paper there are compared results of numerical simulation of compressible turbulent flow through a low-pressure turbine blade cascade with relatively thick trailing edges for various physical models. Steady, unsteady, fully turbulent, transitional, two-dimensional and three-dimensional models are compared. Results show that: a) steady simulation gives an incorrect prediction of the boundary layer development, b) two-dimensional unsteady simulation leads to inaccurate prediction of the far wake development and c) only three-dimensional unsteady transitional simulation gives sufficiently accurate prediction. Results of numerical simulations are compared with the experimental data.
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Simulation of Transonic Flow Through a Mid-Span Turbine Blade Cascade with the Separation-Induced Transition
Straka, P. ; Příhoda, Jaromír ; Fenderl, D.
The paper deals with the numerical simulation of the transonic flow through a mid-span turbine blade cascade by means of an in-house code based on the EARSM turbulence model of Hellsten [1] completed by the algebraic transition model of Straka and Příhoda [2]. The simulation using the transition model of Langtry and Menter [3] and Menter et al. [4] implemented in the commercial code ANSYS Fluent was used for the comparison. Simulations were carried out for the transonic regime close to the nominal regime. The flow separation on the suction side of the blade is caused by the interaction of the reflected shock wave with the boundary layer. The attention was focused on the modelling of the transition in the separated flow especially on the modelling of the length of the transition region. Numerical results were compared with experimental results.
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Transition Modelling on Separated Flow in Turbine Cascade
Louda, Petr ; Příhoda, Jaromír ; Kozel, K.
The work deals with numerical simulation of turbulent ow through turbine cascade by RANS model with model of transition to turbulence. Performance of two transition models is compared. First one is gamma-zeta model based on transition criteria, second one algebraic transition model based on the concept of laminar uctuations energy (Kubacki, Dick 2016). The criterion for transition in separated state is re-formulated in order to remove stream-wise non-local formulation. The performance of the transition models is observed on the shock wave - boundary layer interaction on turbine blade.
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