水下吹除排污过程气体射流噪声数值模拟

Numerical simulation of gas jet noise in the underwater blowdown process

[目的]研究水下航行体污水吹除产生的辐射噪声的规律特性和影响因素。[方法]基于大涡模拟(LES)与FW-H方程计算方法,对航行体贮容器排污过程进行流场分析和辐射噪声定量计算。[结果]数值模拟与实验结果均表明,辐射噪声主要受吹除压力和背压压差的影响,压差越大,辐射噪声越大,且其基本不受吹除背压影响。贮容器内水排空后,水下直接喷射排气会产生辐射噪声的“拐点”,排气噪声显著上升;频谱图呈现低频特性,频率主要分布在1500 Hz以内,且有明显峰值。[结论]为控制舰船水下吹除排污过程的辐射噪声量级,应尽量控制排气压差,并防止高压气体直接喷射至海中。

[Objectives]The characteristics and influencing factors of the radiated noise generated by the blowdown of sewage from underwater vehicles is investigated.[M ethods]The flow field analysis and the quantitative calculation of radiated noise of large-diameter air jet were carried out based on Large Eddy Simulation(L ES)and FW-H equation calculation method.[Results]The calculated and experimental results show that the radiated noise is mainly related to the pressure difference between the blowdown pressure and the back pressure,a nd is basically not affected by the blowdown back pressure.As the pressure difference increases,the radiated noise becomes larger.As the sanitary pressurized tank is blown out,the radiated noise experiences a breakthrough and increases significantly due to air jet under the water.Moreover,the spectrum shows a low frequency characteristic.The radiated noise is mainly concentrated in the range of 0-1500 Hz and there are significant peaks appears in the spectrum,and there is a significant peak.[Conclusions]A reasonable measure to weaken the radiated noise during the process of blowdown is to control the pressure difference and prevent the appearing of the high pressure air jet under the sea.