不同环境下射流辐射噪声特性研究

Studies on the Jet Noise Characteristics in Different Environments

水下排气噪声形成机理不同于空气排气噪声的产生机理,为了确定水下排气辐射噪声频谱特性及噪声源,进行了水下和空气气体喷射噪声试验研究。分析比较试验结果发现,气泡从管口脱落以及在流场力的作用下气泡体积振动产生的噪声是影响1~4 kHz频段声压的主要噪声源;当水下排气产生的两相流态由气泡流态过渡到射流流态后,气泡辐射噪声峰值与排气速率之间的线性关系消失,1~5 kHz频段内声压值变化较小,而在5 kHz以上的频段声压增幅较其它流量下却明显增大;水下排气由于气流剪切周围水体所引起的湍流噪声要明显低于空气排气产生的湍流噪声。

As the formation mechanism of underwater exhaust noise is different from that of air exhaust noise,experimental study of underwater and air injection noise were carried out to determine the spectral characteristics of underwater radiated noise and the exhaust noise source.By the analysis and comparison of the test results,it can be seen that the noise generated by bubbles shedding off from the nozzle and the vibration of the bubble volume in the flow force field are the main source of noise in the sound pressure band of 1 kHz to 4 kHz.When the two-phase flow state generated by underwater exhaust transformed from bubble flow state to jet flow state,the linear relationship between the peak of the bubble emission noise and exhaust rate disappeared,and the sound pressure level in the band of 1 kHz to 5 kHz changed small,while in the sound pressure above 5 kHz increased significantly compared with that of other flow rate.The underwater turbulent exhaust noise due to gas shearing water around is significantly lower than that of the turbulence noise generated by gas exhaust.