Numerical Analyses for Aerodynamic and Noise Characteristics of Helicopter Scissors Tail Rotor

Numerical analyses for aerodynamic and noise characteristics of helicopter scissors tail rotor both in hover and forward flight are conducted. A solver named CFD/FW-H method which combines the CFD method and FW-H approach is established to predict the noise characteristics of scissors tail rotor. In this solver, based on the moving-embedded grid system, a CFD simulation method for aerodynamic characteristics of scissors tail rotor is developed by solving the unsteady RANS equations with Baldwin-Lomax turbulence model, and the discretization of convective fluxes is completed by ROE-MUSCL scheme. Then, the differences on aerodynamic and acoustic characteristics between the two types of scissors tail rotors (Configuration L and Configuration U) are discussed. Also, the influences of the two configuration parameters (scissors angle and vertical space) on their aerodynamic and acoustic characteristics have been analyzed both in hover and forward flight. Additionally an optimization procedure based on surrogate model is employed to conduct the optimization for aerodynamic and noise characteristics of scissors tail rotor in hover. It is demonstrated that the aerodynamic and acoustic characteristics of a scissors tail rotor are not always better than those of a conventional one. In addition, Configuration L shows more advantages of improving the aerodynamic and noise characteristics than Configuration U due to the weaker blade-vortex interaction.