Scalable Aerodynamics and Coupled Comprehensive Methods for the Prediction of Rotorcraft Maneuver Loads

Modern rotorcraft, when operating near performance boundaries typical ofhigh-speed or maneuvering flight, can experience complex and highlynon-linear aerodynamics phenomena which induce exceptionally high loads onthe rotor system. The strong interactionbetween the aerodynamics and thestructural dynamics can lead to violent vibrations, reduced handlingqualities, and a reduction in fatigue life. The principle mechanism of thisbehavior is dynamic stall, which involves a cyclic event of massiveflowseparation, vortex shedding and convection over the blade surface. The multidisciplinary nature of the problem necessitates atightly coupled predictive capability.Conventional Navier-Stokes approaches have shown promise but their computational costisprohibitive.Flow Analysis, Inc. (FAI) has developed a technique for predicting dynamicstall using the Vorticity Confinement method incorporated into a compressible flow solver.This approach requires far fewer computational resources when compared toconventional methods.The proposed effort involvesthe integration of the Vorticity Confinement method and a structural dynamics code in a tightlycoupled fashion. Through the judicious use of parallel processing resources, scalable performance can beachieved, making this approachcomputationally practical. The method will be demonstrated on a scalesuitable for a Phase I level of effort and sufficient for proof of concept.The successful completion of the research will result in the developmentof a codethat uses a state-of-the-art comprehensive method tightlycoupled to a high-fidelity aerodynamics method, with a unique and efficientdynamic stall predictive capability. The code will demonstrate excellentperformance and scalability on parallel computers,and with theproper hardware and operating system environment, on workstation or PCclusters. This will provide the Army and U.S. Aviation industry a toolfor improved predictions of high speed and maneuvering flight, immediately at the conclusion of thePhase II effort. Further extensions, in Phase II and Phase III, will provide computational tools that will have many commercialization benefits, including aircraft aeroelastic applications.