Reduced Order Free Wake Modeling for Near Real Time Simulation of Rotorcraft Flight Mechanics

The development of fast, high-fidelity models of rotorcraft flight mechanics is critical to streamlining the design and testing of new aircraft, and it is now possible to bring advanced free wake aeromechanical models to bear on this problem. This paper will describe the development and testing of Reduced Order Hierarchical Fast Vortex (ROHFV) methods that provide dramatically accelerated embodiments of validated free wake models for flight mechanics applications. These methods, embedded in the Continuum Dynamics, Inc. (C.D.I.) CHARM (Comprehensive Hierarchical Aeromechanics Rotorcraft Model) code, produce high fidelity treatments of rotor/wake and rotor/body interaction while yielding near real time, defined as within an order of magnitude of real time, performance on current single-processor workstations. The paper also describes: the addition of maneuvering flight effects to the aerodynamic model, coupling of the ROHFV methodology to a six degree of freedom rotorcraft simulation to yield the framework of a fast, comprehensive flight simulation model; data correlation studies to validate the model; and outlines the steps required to provide an eventual real time free wake simulation capability.