Coupled CSD/CFD and Viscous Vortex Particle Method for Rotorcraft Comprehensive Analysis

In this research, a hybrid solver was developed that consists of a CSD solver, a near body CFD solver, and a state-of-the-art Viscous Vortex Particle Method (VVPM). The hybrid solver includes a multi-body finite element computational structural dynamics (CSD) solver to render an aeroelastic solution for rotorcraft comprehensive analysis. The near body CFD solver concentrates on the body surface airloads computation with dramatically reduced grid nodes and, hence, a significantly reduced computational time. VVPM addresses the complicated rotor wake and solves the vorticity dynamics. The coupling was carried out by propagating CFD generated vorticity sources to VVPM and feeding back the VVPM calculated wake induced velocity to CFD. This paper discusses the fundamental methodology used to couple CSD/CFD and VVPM. To validate the developed coupling methodology, VVPM was coupled with RCAS and OVERFLOW and the hybrid solver was used to predict the blade airloads for a UH-60A rotor in representative forward flight conditions. The simulation results correlated well with the measurements and the coupled solution helps to improve the efficiency and accuracy when compared with the corresponding CSD/CFD solution.