Numerical Investigation of the Effect of Trailing-Edge Morphing on Dynamic Stall using Delayed Detached Eddy Simulations

Abstract

This paper presents a study on the effect of trailing-edge morphing on dynamic stall using delayed detached eddy simulations (DDES). The dynamic stall of a NACA 0018 airfoil is simulated using OVERFLOW CFD, with a freestream Mach number of 0.1 and Reynolds number of 200,000, undergoing a ramp-up pitching motion. First, DDES numerical simulations are used to predict and analyze the aerodynamic loads for the baseline NACA 0018 airfoil and two trailing-edge morphing geometries. The peaks of the coefficients of lift, drag, and moment for the baseline case and the morphed cases are compared to identify trends and percent differences, and to analyze the significance and effect of the trailing-edge morphing design parameter. It is found that modifying the trailing-edge angle has global effects on dynamic stall. For example, the morphed trailing-edge airfoil yields a sizable reduction in the pitching moment without compromising the loss of lift by too much. The dynamic stall development stages, as well as the detailed flow physics and flow features, are analyzed. It is found that the morphed airfoils exhibit stronger secondary shear layer separation in the middle and aft airfoil sections at higher angles of attack (AoAs), compared to the baseline airfoil. It is also found that the morphed trailing-edge with the largest selected design parameter causes the laminar separation bubble (LSB) to burst at an earlier stage, resulting in the dynamic stall vortex (DSV) occurring at an earlier stage compared to the baseline case.