Maneuvering Rotorcraft Noise Prediction: A New Code for a New Problem

This paper presents the unique aspects of the development of an entirely new maneuver noiseprediction code called PSU-WOPWOP. The main focus of the code is the aeroacoustic aspects of the maneuvernoise problem, when the aeromechanical input data are provided (namely aircraft and blade motion, bladeairloads). The PSU-WOPWOP noise prediction capability was developed for rotors in steady and transientmaneuvering flight. Featuring an object-oriented design, the code allows great flexibility for complex rotorconfiguration and motion (including multiple rotors and full aircraft motion). The relative locations andnumber of hinges, flexures, and body motions can be arbitrarily specified to match the any specific rotorcraft.An analysis of algorithm efficiency is performed for maneuver noise prediction along with a description of thetradeoffs made specifically for the maneuvering noise problem. Noise predictions for the main rotor of arotorcraft in steady descent, transient (arrested) descent, hover and a mild "pop-up" maneuver aredemonstrated.NOMENCLATUREc = sound speed in quiescent mediumdl = element of the spanwise integrationdS = element of the integration surface areaf = function defining the integration surfacef = 0L i = components of vector defined in Eq.(5)L u = LiM _Lr