Abstract: Abstract: A computational method based on CFD technology is developed for helicopter main-rotor/tail-rotor/ vertical-tail interaction analysis. In the present method, Navier-Stokes equations are utilized as the control equations, and the Baldwin-Lomax model is used as the turbulence model. Moving embedded grid method is applied to exchange the flowfield information among the grids of main-rotor, tail-rotor and vertical-tail. For the spatial and time discretization, the second-order upwind Roe scheme and implicit LU-SGS scheme are used respectively. By the method developed, example calculations on the flowfield of well-known C-Tung rotors and Lynx tail rotors are performed, and the validity of the present method is demonstrated by comparing the calculated results with available experimental data. Then, numerical simulations for main-rotor/tail-rotor aerodynamic interference are made, furthermore, taking vertical tail interaction into consideration, tail-rotor/vertical-tail and main-rotor/tail-rotor/vertical-tail interaction calculations are conducted to investigate the interaction mechanism among main rotor, tail rotor and vertical tail. It is shown that, for different vertical-tail/tail-rotor configurations, a larger blockage area always leads to a greater tail-rotor trust, but a smaller clean trust of vertical tail and tail rotor. In addition, the clean tail-rotor trusts of “push configuration” are always higher than that of the “pull configuration” for different blockage areas.

Key words: aerodynamic interaction, embedded grid, Navier-stokes equation, helicopter, CFD