Broadband Noise Due to Rotor-Wake/Rotor Interaction in Contra-Rotating Open Rotors

摘要

A semi-analytical model for the prediction of the broadband noise due to the interaction between turbulent rotornwakes and a rotor in contra-rotating open rotors is presented.The unsteady loading of the rear rotor ismodeled usingnclassical isolated flat-plate theory. Strip theory is used to treat the spanwise variations of aerodynamic quantities andnblade geometry. The turbulent wake is assumed to be homogeneous and isotropic turbulence that is modulated by antrain of wake profiles. The model is presented in detail and insight into its modal behavior is provided. A parameternstudy is conducted to investigate the effects of blade number, rotor–rotor gap and rotor speeds on broadband noisenemissions due to rotor–wake/rotor interaction in contra-rotating open rotors. Scaling laws for sound power levelsnhave been established analytically and show good agreement with the results of the parameter study.