INVESTIGATION OF COMPRESSIBLE FLOW THROUGH A TURBINE BLADE CASCADE FOR VARIOUS TRANSONIC FLOW REGIMES

This paper deals with the numerical simulation of 2D transonic flow through the SE1050 turbine blade cascade at various flow conditions. The first one concerns the design operation with a zero incidence angle involved in the ERCOFTAC Database CFD-QNET and the second one with a +20° incidence angle corresponding to an off-design operation. Advanced mathematical models with two different models of the bypass transition to turbulence were applied for the simulation of different regimes of transonic flows as well as with attached and separated flows. Transition models proposed by Dick et al. [1] and by Menter and Smirnov [2] are based on transport equations for the intermittency coefficient. Numerical results were compared with experimental data based on the optical and pressure measurements

Modelling of flow over a backward-facing step in streams with various turbulence level

Turbulent flow over a backward-facing step in streams with a various turbulence level was numerically simulated using software ANSYS CFX-5. Numerical solution carried on with the two-equation SST model and/or with a k-omega based Reynolds stress model was compared with experimental data obtained for three different values of free-stream turbulence level. The predicted length of the recirculation region corresponds well with experimental data but the dependence of the ratio xr/h on free-stream turbulence level is smaller

Numerical simulation of the wall jet on a circullar cylinder

The wall jet on a circular cylinder was simulated numerically using the CFX-TASCflow software. The calculation was carried out for the relative slot height h/R=0.04 and the Reynolds number Reh from 3500 to 21000. Results obtained by the k-eps model and by the BSL and SST models proposed by Menter were compared with experimental data and with empirical relations

Experimentální a numerické modelování turbulentního obtékání příčných prahů v otevřeném kanálu

Modelling of turbulent flow in an open channel with transversal ribs on its bottom was concentrated particularly on the development of flow separation behind ribs and on the corresponding changes of free surface. Further, the pressure drag of individual ribs was investigated including their dependence on the rib spacing, as well as the origin of secondary flow near the side walls of the channel behind ribs. Numerical results obtained by the software ANSYS CFX 11.0 were compared with experiments carried out by means of LDA and PIV techniques in free-surface water channel 200x200 mm with one and/or two transversal ribs 10xl0 mm with various spacing

Porovnání kritérií pro určení zkráceného přechodu

Empirical relations for the bypass transition were compared with experimental data and with numerical results obtained by the Xfoil code for the flat-plate flow. Relations for the transition onset and the length of the transitional region were tested for the effect free-stream turbulence. The effect of wall roughness was considered as well

Modelling of subcritical free-surface flow over an inclined backward-facing step in a water channel

The contribution deals with the experimental and numerical modelling of subcritical turbulent flow in an open channel with an inclined backward-facing step. The step with the inclination angle 20 deg was placed in the water channel of the cross-section 200x200 mm. Experiments were carried out by means of the PIV and LDA measuring techniques. Numerical simulations were executed by means of the commercial software ANSYS CFX 12.0. Numerical results obtained for two-equation models and EARSM turbulence model completed by transport equations for turbulent energy and specific dissipation rate were compared with experimental data. The modelling was concentrated particularly on the development of the flow separation and on the corresponding changes of free surface