蒸汽喷射器射流噪声的数值模拟

Numerical Simulation of Aerodynamic Noise for the Steam Jet of Ejector

采用FLUENT软件,选择大涡模型(LES)对喷射器射流进行了数值模拟。模拟很好地再现了喷射器射流中拟序结构非定常演化的前期过程,成功地捕获到了射流中Kelvin-Helmholtz不稳定性的触发与初级涡环的卷起及其配对合并现象。随后从流场的数值结果中提取出脉动压力作为声源,以声学中的FW-H方程数值求解射流远场的噪声。将计算结果和实验测量结果进行比较,对喷射器射流总体声压级具有较好的模拟精度,但对高频声的模拟结果尚不够很理想。

The free turbulent jet of ejector is modeled and simulated according to Large-Eddy Simulation （LES） based on FLUENT. The unsteady evolution of coherent structures in a turbulent jet of ejector has been reproduced by the model successfully. The Kelvin-Helmholtz instability of the shear layer in the proximal region of the jet flow and the roll-up of the vortex rings and vortex-pairing phenomena of the round jet have been numerically visualized. The pressure pulses separated from the simulation results are used as the noise source to predict the far field noise by means of Ffowcs Williams-Hawkings equation （FW-H）. The comparison between the noise simulation and experimental results shows that the calculated Sound Pressure Levels （SPLs） agree well with the experimental data in most frequency spectrum, but the SPLs at very-high frequency are not quite satisfactory.