亚音速射流实验与流场模拟

Experiment Study and Flow Field Simulation of the Subsonic Jet

本文描述了自行设计并搭建的亚音速射流噪声实验台结构,并在对实验台射流流场品质验证的基础上对射流声场特性进行了初步研究。通过实验给出了喷嘴前扩压段静压与射流流速的标定关系,台架控制系统通过控制扩压段压力调节射流流量以保证喷嘴出口风速。测量了射流流场长度并与理论值相比较,结果表明实验台能提供理想的射流流场。对不同测点的射流噪声频谱特性分析得出与喷嘴出口距离相同的测点的噪声分布规律,即轴向噪声幅值要大于径向,轴向频率特性表现在低频部分,而径向频率特性表现在高频部分。文中还对二维射流流场模拟结果中的射流轴线截面速度及无量纲化速度的自模性进行了分析,验证模拟结果的正确性。

The structure of the self-designed and self-built subsonic jet noise test platform was described and the jet acoustic field characteristics were preliminarily studied based on the tests of the jet flow field quality of the test platform. Through experiments, the calibration relation between the static pressure of the steady pressure area in front of the nozzle and the jet flow rate was built. The control system of the rack was used to ensure the air speed of the nozzle outlet by adjusting the pressure of the steady pressure area to control the jet flow rate. The length of the jet flow field was measured and the result was compared with the theoretical value. It showed that the test platform can provide an ideal jet flow field. The spectral characteristics of the jet noise in different test points were also studied and the distribution rule of the jet noise in the test points having the same distance with the nozzle outlet was got. It showed that the amplitude of the noise in axial was larger than that in the radical and the axial spectral characteristics were mainly in the low frequency part while the radical spectral characteristics were mainly in the high frequency parts. In order to verify the correctness of the simulation results, self-similarity theory was used to analyze the velocity and the non-dimensional velocity of the jet axial cross profile in the two-dimensional jet flow field numerical simulation results.