URANS Analysis of Wake-Induced Effects in High-Lift, Low Reynolds Number Cascade Flows

A URANS analysis of unsteady effects induced by incoming wakes in high-lift, low-Reynolds-number cascade flows has been carried out using a novel, transition-sensitive, turbulence model. It is based on the coupling of two additional transport equations, one for the so-called laminar kinetic energy (LKE) and one for a turbulence indicator function, with a low Reynolds number formulation of the Wilcox k-ω model. Two high-lift cascades (T106C and T2), recently tested at the von Kármán Institute in the framework of the two European research projects UTAT (Unsteady Transition in Axial Turbomachines) and TATMo (Turbulence and Transition Modelling for Special Turbomachinery Applications), were considered for the present study. The analyzed Reynolds number values span the whole range typically encountered in aero-engines low-pressure turbines operations, and both steady and periodically unsteady inflow conditions were considered. A detailed comparison between measurements and computations, in terms of blade surface isentropic Mach number distributions and cascade lapse rates will be presented and discussed. Results with the proposed model show its ability to predict the major effects of passing wakes on the boundary layer development and loss characteristics of high-lift cascades operating in LP-turbine conditions.