# Flow-Induced Noise Characteristics Analysis of a Pipeline Structure in a Cabin Rigid Corner
###### Abstract  
The acoustic radiation characteristics of pipeline structures caused by turbulent fluctuating pressure are among the most important acoustic radiation sources in vessel cabins. Studying the vibro-acoustic characteristics of pipeline structures is of great relevance to engineering. The turbulence fluctuation pressure of pipeline structures' inner surfaces was numerically analyzed by using the large eddy simulation (LES) method. At first, the vibro-acoustic differential equation of the pipeline structure system was derived by defining the fluctuation pressure as the excitation loading. According to the acoustic radiation characteristic in the quarter-infinite space, which had a combination of two rigid wall interfaces at the same time for the pipeline structures in the vessel cabins, the double reflection method, mirror image method and elastic wave Graf addition principle were applied, and the analytical function of the acoustic radiation for the cylindrical shell was derived. For the pipeline structures in the quarter-infinite acoustic space, for example, the numerical calculation for the acoustic radiation of cylindrical shell was carried out, which was excited by the turbulent pulsating pressure. Finally, the influence of inner flow velocity, frequency, and pipeline installation position were compared using numerical analysis. The results can provide technical support for the acoustic design of pipeline structure systems with complex acoustic boundaries. pipeline; fluctuating pressure; flow-induced noise; quarter space; double reflection method +
Footnote †: journal: Medical  
field, and the turbulent pulsating pressure distribution parameter of the fluid-solid surface are discussed [13; 14; 15]. On the other hand, turbulent pulse pressure is a random excitation loading and flow excitation loading is a random force. To analyze the acoustic radiation caused by turbulent pulse pressure, it is necessary to obtain the power spectrum of the turbulent pulsating pressure (the pulse pressure is defined as a virtual excitation force in the vibro-acoustic characteristics analysis) [16; 17]. In structural dynamic analysis, the pipeline structure can be simplified as a cylindrical shell structure system, and the Flugge shell theory can be employed in dynamic response analysis. Applying the analytical solution of the acoustic Helmholtz equation to the cylinder shell structure is possible in free space. However, the acoustic boundary conditions may be irregular or complicated in many engineering domains, and these acoustic boundary conditions may affect the acoustic radiation characteristics. Thus, the influence of the acoustic boundary characteristics, particularly their effect on the control acoustic space, must be considered in the vibro-acoustic problem. Currently, the research result is more mature for the half-space acoustic radiation problem, including concerns with the free interface and rigid wall interface [18]. To solve the complex acoustic radiation problem, the mirror theory is broadened to the three-dimensional domain. Acoustic boundary characteristics have been studied extensively in order to analyze their influence. The double reflection method is presented to address multiple issues caused by the acoustic boundary [19; 20]. Multiple boundary problems can be solved by combining the double reflection method with the elastic wave Graf addition principle and the research scope for vibro-acoustic problems to vibration power flow problems has been extended with the inclusion of the right-angle domain of the acoustic radiation from the cylindrical shell structure [21; 22; 23; 24]. It is necessary and feasible to study the noise characteristics caused by a pipeline structure in a rigid corner of a cabin. The main objectives of the present work were to analyze the influence of acoustic boundaries of quarter-infinite space on vibro-acoustic characteristics of the pipeline structure.