Angle of Attack and Core Size Effects on Transitional Vortical-Gust–Airfoil Interactions

Abstract

This paper presents high-fidelity implicit large-eddy simulations of counterclockwise-oriented parallel vortical gust interactions with a NACA0012 airfoil operating at a transitional chord-based Reynolds number of . Both the angle of attack (, 8, and 12 deg) and gust core size (, 0.25, and 0.50) are varied. In all cases, flow disruptions induced by the various gust encounters are analyzed alongside the corresponding aerodynamic load perturbations. Equivalent inviscid simulations supplement the present flow analyses. Boundary-layer disruption exhibits increased complexity at higher angles of attack characterized by a more coherent leading edge vortex (LEV) and a secondary boundary-layer disruption further downstream. By these features begin to resemble dynamic stall. Both flow laminarization upstream of the induced LEV and lower boundary-layer breakup are less pronounced as angle of attack increases. Interaction with a large gust, , at the lowest angle of attack, , produced a response similar to that observed in the higher encounters, that is, more coherent LEV and secondary boundary-layer disruptions downstream.