Vortex Dynamics for Rotorcraft Interactional Aerodynamics

摘要

Promising results were obtained that indicate that new techniques in the analysis of vortex dynamics could be used as the foundation of a general analysis of rotor/airframe interactions. Prediction of the velocity field downstream of helicopter rotors was addressed first. Using a novel, full-span rotor wake representation constructed of curved vortex elements, accurate qualitative and quantitative predictions of wake velocity data were achieved for rotors in both low- and high-speed forward flight. The flow field predictions illustrated the radical changes that take place in the wake velocity field as speed increases and demonstrated the success of this approach in capturing these variations. New methods for analyzing close interactions between vortices and fixed surfaces were developed. The basis of this new approach is the inclusion of the special treatment of the vortex velocity field for close interactions with paneled surfaces which obviates the need for high local panel density. Model problems were solved featuring vortices in close proximity to flat surfaces and cylinders that amply illustrate the accuracy and efficiency of the new method. (EDC)