Comparative Study of the Propagation of Jet Noise in Static and Flow Environments

In order to analyze the effect of the background flow on the sound prediction of fine-scale turbulence noise, the sound spectra from static and flow environments are compared. It turns out that, the two methods can obtain similar predictions not only at 90 deg to the jet axis but also at mid- and high frequencies in other directions. The discrepancies of predictions from the two environments show that the effect of the jet flow on the sound propagation is related to low frequencies in the downstream and upstream directions. It is noted that there is an obvious advantage of computational efficiency for calculating in static environment, compared with that in flow environment. A good agreement is also observed to some extent between the predictions in static environment and measurements of subsonic to supersonic. It is believed that the predictions in static environment could be an effective method to study the propagation of the sound in jet flow and to predict the fine scale turbulence noise accurately in a way as well.