Quadrupole modeling for prediction of high-speed impulsive noise of propellers

A new far-fjeld approximation to the Ffowcs Williams- Hawkings (FW-H) equation quadrupole source term, originally developed for helicopter rotors, is implemented in a propeller noise prediction code called ProRAPP to predict the highspeed impulsive (HSI) noise of propellers. The FW-H equation with monopole and dipole terms has been frequently used to predict thickness and loading noise of propellers, but to the authors' knowledge modeling of the quadrupole term for the propellers has not been done before and this is the first such modeling. The results are presented for a two-bladed Hartzell propeller with tip region in the transonic range. The components of the quadrupole, thickness and loading noise are calculated and the contribution of high-speed impulsive noise on overall noise is discussed.