Numerical Study On The Aerodynamics Of The Subsonic Jet

Study on the jet noise is always important due to its value on both the engineering and the research filed. After the reading of reference papers, a proper computing domain for the jet flow field and sound field simulation has been composed, and the numerical study has been carried out for both the flow field and the aeroacoustic field. The results are generally consisting with the statistic result of the jet flow.RANS study of the jet flow shows that that the region after the nozzle could be divided into three regions. The first region is the mixing region, where the potential core exists and last to about 7.7 times the diameter of the jet nozzle, in this core potential region, the velocity of the fluid is more or less unchanged. The following transition region is a transition between the mixing region and the full development region. In the full development region, the velocity at the axis reduces inversely portion to the distance from the tube nozzle. In the r-direction, the velocity has a so called"self-similarity"property, which shows that the velocity distribution on the r-direction has the same form on different cross section.Next the LES model and FW-H model is used to compute the transient flow field and aeroacoustic result of the free jet. Results show that the jet noise shows a great directionality on different direction, from 10°to 30°, the acoustic noise is much higher. This directionality is not only related to the property of the quadric pole but also the reflection of sound wave in the flied.Last, the draft about the jet noise setup is presented based on the numerical results we got.