Measurement and prediction of noise propagation from a high-power jet aircraft

The measurement and prediction of noise propagation from a high-power jet aircraft are discussed. The prediction of high-amplitude noise propagation has used various forms of the generalized Mendousse-Burgers equation (GMBE) to model the propagation. The GMBE is a parabolic nonlinear model equation that accounts for quadratic nonlinearity, geometrical spreading, and absorption and dispersion. Researchers have developed an algorithm that is used to propagate an actual T-38 noise recording. Acquisition of the pressure waveforms is carried out using National Instruments 24 bit PXI-4472 DAQ cards with a 96-kHz sampling rate. The temperature and relative humidity sensors are located at different heights to measure gradients near the ground. The linear predictions are direct extrapolations of the calculated one-third-octave spectra at 61 m out to 305 m. The extrapolation includes spherical spreading and atmospheric absorption.