Noise sources and transmission in piping systems

An overview of the vibro-acoustic behavior of fluid-filled piping systems is given, summarizing noise sources, how piping structures and fluids accept energy from noise sources, and how the energy is then transmitted and exchanged by wavetypes throughout the piping. Discrete and broad-band frequency noise sources from active components, such as pumps, and passive components, such as valves and flow over piping, are described, and scale on flow velocities and operating speeds. The turbulence in the fluid flow contributes to piping system noise and vibration. The turbulence in the core flow impinges on both active and passive devices, causing discrete and broad-band noise sources. Turbulence near pipe walls excites structural piping modes. Techniques for quantifying the turbulence and its effects are described. An overview of the mechanisms of acoustic and vibrational energy propagation in piping walls and fluids is given, along with a discussion of various tools used to model the propagation, such as finite element (FE) and boundary element (BE) analysis, transfer matrix (TM) analysis, and statistical energy analysis (SEA). FE and BE models may be used to model high levels of complexity in both structural-acoustic systems and noise sources, but require large model sizes at high frequencies. TM and SEA models sacrifice modeling generality, but can represent high frequency behavior at low computational cost. Finally, means of mitigating acoustic and vibration energy transmission, such as narrow-band acoustic attenuation devices (quarter wavelength silencers and Quincke tubes), broad-band acoustic attenuation devices (mufflers and acoustic filters), and broad-band structural vibration attenuation devices (isolators and rubber piping), are outlined.