A Modified Dynamic Stall Model for Low Mach Numbers

TLDR

The Leishman–Beddoes dynamic stall model, widely used in helicopter and wind turbine aerodynamics, has been refined for high‑Mach helicopter applications but performs poorly at low Mach numbers, especially for stall onset and recovery. The paper proposes a modified dynamic stall model adapted for low Mach numbers. The model introduces a new stall‑onset indicator, a revised return‑from‑stall model, updated chordwise force calculations, and dynamic vortex modeling. Comparisons with the Glasgow University dynamic stall database demonstrate that the modified model yields improved reconstructions of unsteady aerofoil data at low Mach numbers.

Abstract

The Leishman–Beddoes dynamic stall model is a popular model that has been widely applied in both helicopter and wind turbine aerodynamics. This model has been specially refined and tuned for helicopter applications, where the Mach number is usually above 0.3. However, experimental results and analyses at the University of Glasgow have suggested that the original Leishman–Beddoes model reconstructs the unsteady airloads at low Mach numbers less well than at higher Mach numbers. This is particularly so for stall onset and the return from the fully stalled state. In this paper, a modified dynamic stall model that adapts the Leishman–Beddoes dynamic stall model for lower Mach numbers is proposed. The main modifications include a new stall-onset indication, a new return modeling from stalled state, a revised chordwise force, and dynamic vortex modeling. The comparisons to the Glasgow University dynamic stall database showed that the modified model is capable of giving improved reconstructions of unsteady aerofoil data in low Mach numbers.