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This paper focuses on a comparison of experimental and numerical investigations performed on a low-pressure mid-loaded turbine blade at operating conditions comprised of a wide range of Mach numbers(from 0.5-1.1),Reynolds numbers(from 0.4e+5-3.0e+5),flow incidence(-15-15 degrees) and three levels of free-stream turbulence intensities(2,5 and 10%).The experimental part of the work was performed in a high-speed linear cascade wind tunnel.The increased levels of turbulence were achieved by a passive grid placed at the cascade inlet.A two-dimensional flow field at the center of the blade was traversed pitch-wise upstream and downstream the cascade by means of a five-hole probe and a needle pressure probe,respectively.The blade loading was measured using the surface pressure taps evenly deployed at the blade mid-span along the suction and the pressure side.The inlet turbulence was investigated using the constant temperature anemometer technique with a dual sensor probe.Experimentally evaluated values of turbulent kinetic energy and its dissipation rate were then used as inputs for the numerical simulations.An in-house code based on a system of the Favre-averaged Navier-Stokes equation closed by a two-equation k-turbulence model was adopted for the predictions.The code utilizes an algebraic model of bypass transition valid both for attached as for separated flows taking in account the effect of free-stream turbulence and pressure gradient.The resulting comparison was carried out in terms of the kinetic energy loss coefficient,distributions of downstream wakes and blade velocity.Additionally a flow visualization was performed by means of the Schlieren technique in order to provide a further understanding of the studied phenomena.A few selected cases with a particular interest in the attached and separated flow transition are compared and discussed.
This paper focuses on a comparison of experimental and numerical investigations performed on a low-pressure mid-loaded turbine blade at operating conditions comprised of a wide range of Mach numbers (from 0.5-1.1), Reynolds numbers (from 0.4e + 5-3.0 The experimental part of the work was performed in a high-speed linear cascade wind tunnel. (e + 5), flow incidence (-15-15 degrees) and three levels of free-stream turbulence intensities The increased levels of turbulence were achieved by a passive grid placed at the cascade inlet. A two-dimensional flow field at the center of the blade was traversed pitch-wise upstream and downstream the cascade by means of a five-hole probe and a needle pressure probe, respectively. The blade loading was measured using the surface pressure tapsmply deployed at the blade mid-span along the suction and the pressure side. The inlet turbulence was investigated using the constant temperature anemometer technique with a dual sensor probe. Experimentally evalua ted values of turbulent kinetic energy and its dissipation rate were then used as inputs for the numerical simulations. Ann in-house code based on a system of the Favre-averaged Navier-Stokes equation closed by a two-equation k-turbulence model was for the predictions. The code utilizes an algebraic model of bypass transition valid both for attached as for separated flows taking in account the effect of free-stream turbulence and pressure gradient. The resulting is was out of terms of the kinetic energy loss coefficient, distributions of downstream wakes and blade velocity. Additionally a flow visualization was performed by means of the Schlieren technique in order to provide a further understanding of the studied phenomena. a few selected cases with a particular interest in the attached and disconnected flow transition are compared and discussed.