EFFECTS OF GEOMETRY PARAMETERS ON AERODYNAMIC CHARACTERISTICS OF ROTOR AIRFOIL IN REVERSE FLOW

When rotorcrafts fly at high speeds, the retreating blades experience reverse flow due to their high advance ratio. Flow separates even at small angle of attack in reverse flow, which leads to negative lift, drag and pitching moment penalties. The aerodynamic characteristics of an airfoil are closely related to its geometric shape. Therefore, to mitigate aerodynamic deterioration caused by reverse flow and enhance the flight performance of rotorcrafts at high speeds, it is crucial to study the effects of geometric parameters on the aerodynamic characteristics of rotor airfoils in reverse flow. Given that conventional URANS method with low-precision scheme cannot adequately capture the vortex-induced large separation flow in reverse flow conditions, an improved high-order WENO scheme and IDDES method are used in airfoil reverse flow simulation. Initially, the simulation method is validated against experiment data of NACA 0012 airfoil in reverse flow. Subsequently, the OA312 airfoil is selected as a baseline and morphed by leading-edge radius, camber, camber crest position, thickness, thickness crest position and shape of trailing-edge. The aerodynamic coefficients of these modified airfoils are simulated and compared to analyze the influence of different geometry parameters. The results can be used to guide the design of new rotor airfoil with high performance.