Fly-over noise measurements and simulation for a turboprop aircraft

The study of aircraft noise started in earnest in the 1960s, however, the validation of comprehensive noise models for existing commercial aircraft using well-defined experimental data have since produced modest advances. Considerable focus appears to have been placed on aircraft conceptual design, with relatively little effort considering aircraft currently in use, for which we believe there is a growing need. This study investigates the fly-over noise from a commercial turboprop aircraft, using noise measurements taken both on airport departure and approach for the validation of noise simulations. Predictions are carried out using a software system described elsewhere in the literature. It is shown that, for the examples considered, predicted overall noise levels such as SEL and EPNL display modest agreement, and are within 4.3dB/EPNdB of measured values. One-third octave band analysis shows discrepancies to be due to a general under prediction at low to mid frequencies. Through an analysis of noise source subcomponents, the most likely candidates are identified for which an alteration in the model best improves agreement. By applying these alterations – in particular, by increasing the contribution of the landing gear and airframe noise – an average error in one-third octave band SPL of less than 3.2dB is achieved.