湍流喷注噪声定律的发展

  目的  为研究水下射流噪声特性，  方法  应用Lighthill声类比计算轴对称直喷管的自由射流声场特性，借助FLUENT仿真软件并采用大涡模拟法计算该直喷管的水下射流流场，最后基于混响法进行实验验证。  结果  结果表明：稳态射流流场的核心区长度与流速无关，核心区长度约为喷管直径的8倍；射流噪声辐射功率与流速的8次幂成正比；不同流速下的射流噪声功率谱在低频段的差异较大，在高频段的差异则显著减小，且辐射噪声能量主要集中在低频段，但流速增加后射流噪声的主要贡献将向高频段移动。
  结论  在射流噪声计算仿真方面，将大涡模拟法和Lighthill声类比相结合是一种有效的分析手段。

Development of the law of turbulent jet noise

  Objectives  In order to study the underwater jet noise characteristics,  Methods  the Lighthill acoustic analogy is carried out to compute the underwater free jet flow sound field characteristic of axisymmetric nozzle, with applying of FLUENT simulation software and large eddy simulation, the real flow field of submerged axisymmetric nozzle is simulated, and the jet noise is measured by the reverberation method.  Results  The results show that the core length of steady flow field is independent of flow rate, and the length is about 8 times the diameter of the nozzle. The radiation power of jet noise is proportional to the velocity of eight times. The power spectrum of jet noise is different with the flow velocity in the low frequency.
In the high frequency, the difference is significantly reduced. The radiated noise energy is mainly concentrated in the low frequency. With the increase of flow velocity, the main contribution of jet noise moves to high frequency.  Conclusions  In terms of computing simulation of jet noise, the large eddy simulation and Lighthill acoustic analogy combined analysis is an effective means.