Measurement and Prediction of Aerodynamic Noise in Aircraft Ventilation Systems

This paper revisits the scaling laws proposed by Nelson and Morfey for aerodynamic sound generated by spoilers in low flow ducts and applies their prediction method for aircraft ventilation systems. A review of the original method and the modifications it has undergone over time is carried out. New data is presented for aircraft ventilation systems components such as dampers, orifice plates, curves, T- and Y- junctions and conical transitions. Generalized curves are then obtained by means of the scaling laws for each component and applied to a 1-D direct prediction approach for multiple in-duct elements in two different systems. The experimental results confirm the method to be reliable and can be used for predicting aerodynamic noise in a wide range of applications.