Fast Lifting Surface Models for Rotorcraft Analysis

Current comprehensive rotorcraft analyses typically use lifting line theories coupled with 2D look-up tables to determine rotor blade lift, drag and pitching moment. These methods cannot directly capture 3D flow effects that influence the aerodynamic characteristics of advanced planforms, complex tip-shapes and low aspect ratio wing/tail surfaces. CFD codes have been coupled to comprehensive codes to provide this capability, but these coupled solutions are too computationally expensive for daily design work. This effort will see the advancement of fast lifting surface blade models for use in rotorcraft analyses to bridge the gap between current lifting line models and full CFD solutions without excessive increase in computation time. The lifting surface models will directly capture 3D flow effects and directly compute lift, induced drag and pitching moment in turnaround times commensurate with daily design work. The proposed approach is to accelerate and expand upon the lifting surface models incorporated into CDI’s CHARM Blade Aerodynamics Module to provide greater capability and higher resolution solutions in reasonable computation times. The CHARM Module is designed to couple easily with existing rotorcraft analyses. Predictions for relevant configurations will be performed and compared with those obtained with lifting line methods to evaluate expected gains.