Parallel Simulation of Lifting Rotor Wakes

Abstract

The chapter discusses parallel simulation of lifting rotor wakes. Lifting rotors in both hover and forward flight are considered in the chapter. These flows are extremely expensive to simulate using finite-volume compressible computational fluid dynamics (CFD) codes because of the requirement to capture the vortical wake and its influence on the following blades, over many turns. To capture the wake to any reasonable accuracy thus requires very fine meshes, and so, an efficient parallel flow solver is developed and presented in the chapter. The code is an implicit unsteady, multiblock, multigrid, upwind finite-volume solver, and is parallelized using MPI. An efficient structured multiblock grid generator is also developed to allow generation of high quality fine meshes. Results of four-bladed rotors in hover and forward flight, in terms of global loads, wake capturing, and more detailed flow features, are presented and analyzed, using meshes of up to 32 million points, and excellent parallel performance on up to 1024 CPUs is demonstrated in the chapter.