Large-Eddy Simulation of Compressible Transitional Flows in a Low-Pressure Turbine Cascade

Abstract

Large-eddy simulation of compressible transitional flows in a low-pressure turbine cascade is performed by using sixth-order compact difference and a 10th-order filtering method. Numerical results without freestream turbulence and those with about 5 % of freestream turbulence are compared. In these simulations, separated flows in the turbine cascade accompanied by laminar-turbulent transition are realized, and the present results closely agree with past experimental measurements in terms of the static pressure distribution around the blade. In the case where no freestream turbulence is taken into account, the unsteady pressure field essentially differs from that with strong freestream turbulence. In the no freestream turbulence case, pressure waves that propagate from the blade's wake region have noticeable effects on the separated-boundary layer near the trailing edge and on the neighboring blade. Also, based on the snapshot proper orthogonal decomposition analysis, dominant behaviors of the transitional boundary layers are investigated.