Generation of unsteady incoming wakes for wake/blade interaction

Abstract

In this study, an effective method is proposed for the generation of unsteady incoming wakes to facilitate numerical simulation of wake/blade interaction. The wakes are specified through the inflow boundary conditions of a blade cascade, which includes the mean velocity defect as well as the velocity fluctuation induced by the vortex street in wakes. Compared to the large-eddy simulation (LES) of turbine cascades, the proposed method can be used to obtain unsteady wakes with different scales of fluctuation. Further, the analysis reveals that the velocity defect can be well fitted by the Gaussian model, and the velocity perturbation induced by wake vortex can be described by the modified Lamb-Oseen vortex or the Taylor Vortex. The vortices in wakes exhibit self-similarity behavior, which also confirms the feasibility of the proposed method. The wake/blade interaction is also simulated within T106 cascade with incoming wakes generated by the proposed method, and the results provide detailed information on the wake transportation in downstream bladerow.