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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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Intermitence factor evaluation by bypass boundary layer transition in flows on rough surface on flat plate
Skála, Vladislav ; Antoš, Pavel
Bypass boundary layer transition in flows on rough surface on flat plate was investigated experimentally. It was measuered cases with combination of roughness of surface by different free stream turbulence intenzity. Hot wire anemometry technique was used. Measuerement were made on flat plate in closed wind tunnel. Flat plate was covered by different roughness foils (sandpapers). Adverse pressure gradient was set by diffuser in tested section of wind tunnel. Grid turbulence of free stream was controlled by grid. Hot wire anemometry technique was used, intermitency factor was evaluated.
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Development of Boundary Layer on a Heated Flat Plate
Antoš, Pavel ; Kuznetsov, Sergeii
An experimental study of boundary layer on a flat plate with heat transfer was done. Temperature and velocity boundary layer development was studied on a uniformly heated flat plate with zero pressure gradient by means of hot-wire anemometry. Several levels of heat flux at the wall were used. The difference between the wall temperature and free-stream temperature was set up to 180 K. Measurements were performed in the closed-circuit wind tunnel with zero pressure gradient at free-stream velocity of 3-5 m/s and turbulence intensity of 0.8 percent. The velocity and the temperature profiles of mean values and fluctuations are presented.
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Simulation of flow through the tip-section turbine blade cascade for various inlet conditions
Straka, P. ; Příhoda, Jaromír
The contribution deals with the numerical simulation of 2D compressible flow through a tip-section of the turbine blade cascade using the EARSM turbulence model completed by the algebraic transition model. Predictions were carried out at the Reynolds number Re2is = 1.85E+06 for Mach numbers M2is = 1.77 and 1.92. The study was focused on the effect of small changes of flow inlet angle and changes of free-stream turbulence on flow structure in the blade cascade, especially on the shock wave/boundary layer interaction.
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Modelling of the Laminar/Turbulenttransition on a Heated Flat Plate Using the k-kL-w Model
Kožíšek, Martin ; Fürst, J. ; Příhoda, Jaromír
The contribution deals with the numerical simulation of the transition to turbulence on a heated flat plate by means of the k-kL-k-kL-w model of Walters and Cokljat (2008). The revised version of the three-equation model was implemented into the OpenFOAM code for the incompressible and compressible flows. Numerical simulations of the boundary-layer development were carried out according to measurements of Sohn and Reshotko (1991). The transition model was tested by means of the skin friction and the Stanton number distributions for various free-stream turbulence levels. Results were compared with empirical correlations expressing the Reynolds analogy according to Kays and Crawford (1993) and with experimental data of Pinson and Wang (2000).
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A comment on the flat plate leading edge shape on laminar-turbulent transition
Antoš, Pavel ; Jonáš, Pavel ; Procházka, Pavel P.
Laminar-turbulent transition region is investigated in zero pressure gradient boundary layers developing on flat plates with different shapes of leading edges namely with the elliptical profile; the superelliptical one and with the thin circle profile. The mean flow field characteristics are presented and discussed. Near downstream from the leading edge are mean velocity profiles very similar to the Blasius solution in all compared configurations. The dramatic effect of the leading edge is ascertained in the beginning of the skin friction coefficient deflection from the course after Blasius solution. The start of deflection is moving downstream in sequence: elliptic – super-elliptic – circle shape. The length of the transitional region shortens in the opposed sequence.
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