On the effects of time scaling on the noise radiated by the X-33 engine plume

Abstract

Following the experimental and numerical results presented in [1], a study on the effects of time scaling on the predicted acoustic radiation results is carried-out in the present paper. CFD results obtained with a (£, s) turbulence model are used to obtain far-field acoustic spectra using four different time scales. The first three time scales are associated with the inverse of the meanshear, the production and the dissipation rates of the turbulent kinetic energy, respectively. The fourth time referred to as dual time scale takes into account both the production and the dissipation rate of the turbulent kinetic energy. It is found that the calculated spectrum using the dual time scale gives the best agreement with that measured across the entire frequency spectrum. The calculated spectra using the production rate and the mean-shear give a reasonably good agreement at low frequencies, whereas the spectrum obtained using the dissipation rate of the turbulent kinetic energy gives a fair agreement only at high frequencies.