Novel Eulerian Vorticity Transport Wake Module for Rotorcraft Flow Analysis

Accurate rotorcraft performance prediction is essential to both the design and development of rotorcraft, and also the support of flight testing, establishing of safe flight envelopes and analysis of flight operations. While current Lagrangian- and Eulerian-based analysis tools can, in principle, model the complete rotorcraft, in practice these implementations are severely hampered by accuracy limitations broadly attributed to modeling assumptions (for Lagrangian methods) or numerical deficiencies (e.g. excessive numerical diffusion for Eulerian CFD methods using computationally feasible grid scales). Because of these limitations, commonly used design and analysis tools fail to adequately predict the unsteady 3D wakes and load distributions of new rotor and fuselage designs. What has long been needed is an approach that retains the first-principles physical modeling capability offered by Eulerian schemes with the vortex preservation capabilities and low numerical diffusion generally enjoyed by vortex techniques. Enabled by recently developed breakthrough technologies in Eulerian rotor wake modeling that specifically address the critical numerical diffusion issue, the proposed effort will develop a first-principles based Eulerian vorticity transport wake module that when coupled to suitable CFD tools will provide an unprecedented improvement in capturing the true temporal and spatial unsteadiness of the rotor wake using readily available computational resources.