Wall-resolved large eddy simulations of a pitching airfoil incurring in deep dynamic stall

TL;DR

This paper uses wall-resolved large eddy simulations to study deep dynamic stall on a pitching NACA 0012 airfoil, comparing results with experimental data and other numerical models to understand flow physics.

Contribution

It demonstrates the importance of computational span size in LES for accurately capturing vortex dynamics during deep stall.

Findings

LES results agree with experimental data in flow behavior

A span-to-chord ratio of at least one is necessary for accurate LES

All models show similar flow physics and deviations from experiments

Abstract

This study investigates the flow evolution around a sinusoidal pitching NACA 0012 airfoil, defined by the National Advisory Committee for Aeronautics (NACA), undergoing deep dynamic stall using a wall-resolved large eddy simulation (LES) approach. Numerical results are assessed against experimental data from Lee and Gerontakos (2004) at Reynolds number Re = 135 000 and reduced frequency k = 0.1. A comprehensive analysis of the computational model span size is presented, highlighting the requirement for a span-to-chord ratio of at least one to correctly capture the dynamic stall vortex physics in the downstroke phase. Furthermore, a comparative assessment with state-of-the-art Reynolds-Averaged Navier-Stokes (RANS), hybrid RANS/LES, and the experimental data is carried out. All the numerical models concur to the same flow behavior and exhibit similar differences with the experiments.