Three different aerodynamic models are used to analyze a modern lift-offset coaxial helicopter in high-speed cruise. The first and simplest method, dynamic inflow, is used along with Computational Structural Dynamics (CSD) to determine the trimmed flight conditions at speeds up to 250 kt. Two higher order models, the Viscous Vortex Particle Method (VVPM) and Computational Fluid Dynamics (CFD) are then used to evaluate the same trimmed condition at a speed of 230 kt. VVPM is capable of capturing the rotor to rotor interference from first-principles at a significantly lower cost than CFD. The high resolution CFD solution revealed significant deviations in the airloads from the values obtained with the first two methods.
Proceedings of the AHS Specialists’ Conference on Aeromechanics Design for Transformative Vertical Flight, San Francisco, California, Jan 16-19, 2018.