Numerical investigation of dynamic stall on wings following curved trajectory

Abstract

Unsteady aerodynamic flows play a pivotal role in both engineering applications and natural phenomena, with dynamic stall representing a particularly critical challenge. This phenomenon not only degrades aerodynamic efficiency but also induces unsteady loads and aeroelastic responses that can compromise structural integrity. However, the evolution of dynamic stall under complex kinematics remains inadequately understood. This study aims to advance the understanding of dynamic stall mechanisms and to develop computationally efficient models that retain essential nonlinear flow features. We first employ high-fidelity direct numerical simulations (DNS) using the spectral element solver Nek5000 to study a wing undergoing circular motion at the reduced frequencies k = 0.6, representing light stall conditions. Modal analysis, such as proper orthogonal decomposition, was applied to the spanwise vorticity field to better understand the evolution of the dynamic stall vortex and the corresponding flow structures. Despite the accuracy of DNS, its high computational cost limits its practical application and the feasibility to study the far wake. Thus, the second part of this study explores a reduced-order modelling approach using an advanced actuator line model to investigate dynamic stall on a plunging wing. While conventional actuator line models have inherent limitations in capturing unsteady phenomena, we incorporate force coefficients extracted from DNS results to reconstruct the flow fields within the actuator line model to bridge this gap. The spectrum of the induced velocity is compared with analytical results from a novel linear theory for unsteady aerodynamics in actuator line method (Alva et al. 2025). The results demonstrate that the advanced actuator line method is capable of capturing parts of the unsteady effect from dynamic stall and the near wake. This highlights the potential to model dynamic stall using the actuator line method and underscores the feasibility of integrating a dynamic stall model and wake study within this approach.