水下气体射流噪声产生机理与控制研究

Underwater exhaust process involves complex multiphase flows, which accompanied by associated complex phenomenon of layer flow transition, vortex motion and flow pattern changes. The noise generation mechanism is different from the generation mechanism of air exhaust noise. Therefore, in order to design the underwater exhaust muffler, spectrum characteristics of noise and its influence factors must be well studied. This project is proposed based on the former study of project pipeline underwater exhaust noise. In this project, the evolution of underwater gas jet flow will be analyzed, and the intrinsic link between the radiation noise and flow characteristics of two-phase flow field will be researched, then, the underwater the generation mechanism of gas jet radiated noise will be explored. The radiated sound field of underwater gas jet is the main study object of this project. Experiments and numerical simulation on the underwater gas flow field and radiated sound field are combined to reveal the evolution mechanism of underwater two-phase flow field flow and the radiation noise. The numerical simulation methods of underwater jet gas phase flow field and radiation sound field will be established based on the study of description methods of radiation sound field during the underwater gas jet process. The influences of factors, such as nozzle structure, environmental pressure, water content, on the radiated noise of underwater gas will be studied by experimental and numerical methods, and then, the dimensionless relationship between the various parameters will be established. In the end, the control theory and methods of underwater gas jet noise will be improved, providing the basis for the designing and optimization of underwater exhaust muffler device, and also providing the theoretical basis for the control of underwater jet noise.

水下排气过程涉及了复杂的多相流动，伴有层流转捩、旋涡运动和流态变化等复杂现象，其噪声产生机理有别于空气排气噪声机理，因此在水下排气消声器设计前应首先掌握其噪声的频谱特性及影响因素。本项目将在已有工程管路水下排气噪声研究的基础上，研究水下气体射流场的流动演化规律，分析其辐射噪声与两相流场流动特征之间的内在联系，探索水下气体射流辐射噪声的产生机理。项目以水下气体射流的辐射声场为研究对象，展开水下气体射流场及辐射声场的试验及数值模拟研究，揭示水下两相射流场流动演化机理及辐射噪声特性；研究水下气体射流过程中辐射声场的描述方法，建立水下气体射流两相流场及辐射声场的数值模拟方法；通过试验和数值方法研究喷管结构、环境被压、掺水量等影响因素对水下气体射流辐射噪声的影响，建立各个参数间的无量纲关系，完善水下气体射流噪声控制理论及方法，为水下排气消声装置的设计及优化提供依据，为水下射流噪声的控制提供理论基础。

水下排气过程涉及了复杂的多相流动，伴有层流转捩、旋涡运动和流态变化等复杂现象，其噪声产生机理有别于空气排气噪声机理，因此在水下排气消声器设计前应首先掌握其噪声的频谱特性及影响因素。本项目的研究工作主要是通过实验观测和数值模拟来探索水下气体射流过程中的非定常流动及射流噪声的产生机理。进行了水下气体射流观测及噪声测试试验，通过流场与噪声频谱分析，揭示了水下气体射流流动演化规律及辐射声场特性，为研制水下两相射流消声器提供了可靠的参考依据。在研究过程中，提出了一种基于混合算法的噪声数值模拟方法，并通过经典试验验证了数值方法的有效性，为探索水下射流噪声关键影响因素提供了研究工具。通过一系列的试验研究和数值模拟，掌握了喷管结构、形状、掺水量等影响因素对水下气体射流辐射噪声的影响，建立各个参数间的无量纲关系，设计了水下两相射流消声喷头。本项目的研究成果完善水下气体射流噪声控制理论及方法，同时，也可为水下热动力排气系统降噪控制及大型水下航行器消声器的研制提供了设计依据和参考。