CFD/CSD coupling analysis on aerodynamic characteristics of rotor in hover based on non-inertial frame.

In order to enhance the analytical accuracy of advanced rotor aerodynamic characteristics, the aero-elastic effects are coupled into high fidelity CFD analysis method instead of rigid blade assumption. Considering the quasi-steady characteristics of rotor flowfield in hover, a CFD/CSD coupling analysis model for the helicopter rotor is developed based on the non-inertia frame. Airloads are obtained through solving 3-D Navier-Stokes equations with Jameson central difference scheme used in spatial discretization, five-step Runge-Kutta method adopted in temporal integration and B-L turbulent model. Based on the Hamilton principle, nonlinear differential equations which describe the elastic motions of the rotor are formulated and then calculated by Raphson iteration method. During the process of coupled CFD/CSD calculations, airloads and deformation information are exchanged between CFD and CSD module, and grid deformation method based on the direct coordinate transformation is adopted to improve grid deformation efficiency. Finally, the surface pressure distributions and airloads of UH-60A helicopter in hover are calculated, and it is demonstrated that the present CFD/CSD coupling model can predict rotor airloads more accurately compared to CFD method with rigid rotor assumption. [ABSTRACT FROM AUTHOR]