Effect of wake adaptation on rotor hover simulations using unstructured meshes

Abstract

A three-dimensional inviscid flow solver is developed for simulating the flowfield of hovering helicopter rotor using unstructured meshes. The flow solver utilizes a cell-centered finite volume scheme that is based on the Roe's flux-difference splitting with an implicit Jacobi/Gauss-Seidel time integration. Calculations are performed at two operating conditions of subsonic and transonic tip Mach numbers. A solution-adaptive mesh refinement technique is adopted to improve the resolution of flow features on the blade surface. It is demonstrated that the trajectory of the tip vortex can be captured through a series of adaptive mesh refinements starting from a very coarse initial grid. It was found that not only the strength of the tip vortex, but also its trajectory, is strongly dependent on the mesh resolution in the wake. Good agreement is obtained between the numerical result and the experiment for both the blade loading and the tip vortex behavior.