1 research outputs found
Noise prediction of a shortcowl jet using energy transfer rate time-scale
No full textFrequency dependency of the defining parameters in aero-acoustics has been a controversial
issue and many theoretical and experimental studies have been directed towards its
understanding and modelling. In this paper a new time scale based on the turbulent energy
transfer rate is introduced and used along with the MGBK method for a short-cowl nozzle. The
required CFD results for noise prediction are obtained using a modified k ? e turbulence model.
Numerical results are provided for two flow working conditions, bypass velocity ratio 1 and 0.9.
Besides the comparisons of the new time scale against the traditional time scale, namely
dissipation time scale, corresponding noise prediction results at ninety degrees as well as other
angles are compared and discussions are provides. Generally, results show that the new time
scale is capable of performing the anticipated frequency dependency and has significantly
improved noise prediction, particularly at low and high frequencies
