Novel Hybrid Vorticity Transport CFD for Rotorcraft Analysis

Accurate performance prediction is critical to rotorcraft design and development, and while significant gains have been made in rotorcraft CFD-CSD methods, predicting unsteady wake aerodynamics remains a significant challenge. Current analysis tools can theoretically model the complete rotorcraft, but are hampered by modeling assumptions (for Lagrangian methods) and numerical formulation (for CFD). Commonly used analysis tools fail to adequately predict the load distribution on arbitrarily shaped rotors and fuselages and the wake induced unsteadiness. The proposed effort addresses these limitations by building upon prior work in rotorcraft CFD-CSD coupling to develop an innovative hybrid vorticity transport CFD method for predicting aerodynamics in comprehensive rotorcraft analyses. Enabled by work at CDI developing a hybrid vorticity-velocity formulated CFD solver (VorTran-M), the proposed approach, consisting of a fully coupled OVERFLOW-VorTran-M hybrid analysis that can directly interface with the U.S. Army’s RCAS comprehensive analysis will improve airloads prediction capabilities by capturing blade vortex interactions, as well as rotor-fuselage and main-rotor-tail-rotor interactions. Phase I will see enhancement of a prototype OVERFLOW VorTran-M coupling developed in prior work, along with an assessment of the influence of viscous terms on wake evolution and an investigation of methods to enhance the computational performance on massively parallel computers.