Highly-efficient CFD calculations on viscous flow of hovering rotor based on the implicit algorithm

To improve the CFD compute efficiency on the viscous flow of helicopter rotor, a highly-efficient implicit LU-SGS algorithm and OpenMP parallel strategy have been employed for predicting the aerodynamic characteristics of hovering rotor. Firstly, the orthogonal and body-fitted grid around rotor blade is generated by using Poisson equations and folding approach; then the “disturbance diffraction method”(DDM) and “Inverse map” method are utilized in the identification of hole cells and searching the donor cells respectively, thus to solve the bottleneck problem of the embedded grid technique. On these bases, the RANS equations coupled S-A turbulence model in a rotating frame are used as the governing equations, and the three-order scheme of ROE-MUSCL is used for spatial discretization of convective fluxes, and the highly-efficient implicit scheme of LU-SGS is adopted for temporal discretization, and data sharing OpenMP parallel strategy is employed to accelerate the calculation as well. Finally, the flowfield and aerodynamic characteristics of several rotor airfoils and hovering rotors(C-T and UH-60A rotor) have been simulated by the presented method. At the same time, a refined grid strategy according to the position of vortex core has been conducted to improve the capturing accuracy of blade-tip vortex. By comparisons of numerical results with experiment data, high-efficiency and high-accuracy abilities of the present method on the simulation of the rotor flowfield is demonstrated.