Development of Adaptive Vorticity Confinement Based CFD Methodology for Rotorcraft Applications

The accurate representation of the rotor wake, especially the tip vortex structure, in a computationally efficient and algorithmically straight forward way is crucial for prediction of rotor aerodynamic performance, noise emission, and rotor structural dynamics. A promising approach for design and optimization is the vorticity confinement (VC) method that minimizes the numerical diffusion of vorticity in the vortical flow regions. The remaining challenge is to remove the tuning of model parameters to make the method truly predictive and robust. We will develop a fully adaptive VC (AVC) method based on a new formulation. Auxiliary numerical treatments will be implemented that can detect and mitigate potential instabilities, borrowing the idea from shock capturing schemes. We will assess the AVC method in different types of numerical schemes, particularly the spatial discretization scheme. A procedure to determine model parameters dynamically will be constructed dependent on the numerical schemes employed. As a result, it is expected that the new VC methodology will be broadly applicable and characterized for a range of numerical schemes. The Phase II AVC implementation will address rotorcraft applications, including strong transients, rotor noise due to blade vortex interaction, rotor-body nonlinear interactions, and aeroelasticity of the rotor blades.