Numerical calculation research was performed for helicopter main-rotor/tail-rotor interaction by using the CFD method. A computational method was established for aerodynamic interactions of main-rotor/tail-rotor configuration

wherein the three-dimensional unsteady Reynolds-averaged Navier-Stokes (RANS) equations were used as the control equations

and overset grid technique was employed to simulate the relative motion between the main-rotor and tail-rotor. Based on the developed method

the aerodynamic characteristics of main-rotor/tail rotor interaction in hover

low-speed forward flight and cruising state were calculated

and the influence of the tail-rotor rotation direction on the interaction characteristics was analyzed. The results indicate that the interference influence of main-rotor on tail-rotor is obvious in all calculation states

but not always negative

depending on the flight condition. The interference influence of tail-rotor on main-rotor is relatively obvious in hover

but negligible in forward flight condition. In addition

the tail-rotor rotation direction has a significant effect on the aerodynamic force of tail-rotor

so reasonable selection of the tail-rotor rotation direction can improve the aerodynamics of tail-rotor.