Simulation of Unsteady Rotor-Fuselage Aerodynamic Interaction Using Unstructured Adaptive Meshes

A three-dimensional parallel Euler How solver has been developed for the simulation of unsteady rotor-fuselage interaction aerodynamics on unstructured meshes. To handle the relative motion between the rotor and the fuselage, the How field was divided into two zones, a moving zone rotating with the blades and a stationary zone containing the fuselage. A sliding mesh algorithm was developed for the convection of the flow variables across the cutting boundary between the two zones. A quasi-unsteady mesh adaptation technique was adopted to enhance the spatial accuracy of the solution and to better resolve the wake. Mesh deformation from the blade motion in forward flight was treated by using a spring analogy and cell edge-collapsing. A low Mach number pre-conditioning method was implemented to relieve the numerical difficulty associated with low-speed forward flight. Validations were made by simulating the flows around two wind tunnel configurations and comparing the predicted time-averaged and instantaneous inflow and fuselage surface pressure distributions with experimental data. It was shown that the present method is efficient and robust for the prediction of complicated unsteady rotor-fuselage aerodynamic interaction phenomena.