Numerical Investigation of Turbulent Junction Flow Horseshoe Vortex Dynamics

Abstract

The bimodal behavior of turbulent junction flows is associated with a low-frequency unsteadiness that can have implications for the overall performance of engineering applications. The literature suggests that the bimodal behavior may be correlated with upstream boundary-layer events. To test this hypothesis, large-eddy simulations of a generic junction flow with Rood wing geometry were performed for a Reynolds number of 7000 based on airfoil thickness and approach flow velocity. Pulsed disturbances were deliberately introduced upstream of the junction to generate deterministic boundary-layer events. The variable-interval time-averaging method was employed to evaluate the effectiveness of the forcing and track the downstream development of the boundary-layer events. Cross correlations of this quantity with the circulation of the junction flow horseshoe vortex were computed to quantify the dependence of the bimodal behavior on the upstream disturbances. Several of the observed boundary-layer events led to a loss of coherence of the horseshoe vortex. Overall, the present results provide support for the hypothesis that the bimodal behavior is related to upstream boundary-layer events.