High-resolution simulation and parametric research on helicopter rotor vortex flowfield with TAMI control in hover

In order to investigate the effect of active jet control on the rotor vortex flowfield in hover, a high-accuracy numerical method is presented in this paper, and a novel computer code is developed to calculate rotor flowfield with tip air mass injection. In the present computational fluid dynamics method, the Navier-Stokes equation is selected as the governing equation. For the sake of reducing numerical diffusion in calculation, the upwind Roe scheme with a fifth-order WENO scheme is employed to spatial discretization. A dual-time method is utilized in time marching and the high-efficiency implicit LU-SGS scheme is applied to every pseudo time step. The Baldwin-Lomax turbulence model is employed for eddy viscosity modeling. A surface boundary condition, which may effectively simulate the effect of tip air mass injection, is introduced into the current method. The overset grid method, which can veritably simulate the rotor blade motion, is adopted to exchange the flowfield information between the rotor blade and background grids. By the established method, the rotor flowfield with jet control of different jet angles is simulated. Furthermore, parametric analyses of jet velocity are carried out at different tip March numbers and collective pitches. It is demonstrated that tip air mass injection can make the tip vortex rolled up and generated in advance compared with the clean rotor, which can change the position and strength of the vortex core greatly. It is also shown that the rotor aerodynamic characteristics, such as blade surface pressure and radial lift distributions, are more sensitive to tip air mass injection control at the condition with a lower Mach number or a lower collective pitch.