Investigation of the acoustic pressure pulsations in piping system and their effect on the dynamic response of CANDU fuel bundles

电站等工业应用中使用的管道系统容易产生压力脉动，通常是由往复泵的使用和/或阀门的动态不稳定引起的，这可能成为不必要的噪音和振动的来源。如果这些脉动源的频率与管道系统的共振频率相对应，就会产生非常危险的声共振状态，从而产生极大的压力波动，通常是主管道中流动动态扬程的几倍，并且管道系统和周围部件也会产生剧烈的振动。这些情况被称为声诱发振动（AIV），可能会导致垫圈和密封破裂、阀门失效，严重情况下还会导致管道系统、相关部件和仪表的疲劳和断裂。此类故障对安大略发电公司（OPG）生产产生重大影响的一个例子是CANDU核燃料束故障。1990年，达林顿核电站的一个燃料束由于燃料元件过度振动而损坏。因此，本项目的主要目的是通过实验研究被动声阻尼装置对管道系统中声压脉动衰减的有效性，并对CANDU燃料束在声压脉动作用下的动态响应进行数值模拟。从这项研究中获得的知识将为在管道系统中实施新的被动声阻尼装置提供实用的设计指南，以防止声压脉动的发生。此外，还将开发一个更现实的三维模型来预测燃料束在流体激励和声压脉动下的振动响应。这不仅将支持核电厂管道系统的安全性和可靠性的提高，这将直接有利于加拿大的经济，而且还可以用于未来的CANDU反应堆，以避免由于上述激励机制而导致的燃料束失效。

Piping systems used in industrial applications such as power stations are liable to generation of pressure pulsations, often arising from the use of reciprocating pumps and/or dynamic instability of valves, which can act as sources of unwanted noise and vibration. In the event that the frequencies of these pulsating sources correspond to the resonant frequencies of the piping system, a very dangerous acoustic resonance condition can result, which can produce extremely large pressure fluctuations, often several times the dynamic head of the flow in the main pipe, as well as substantial vibration of the piping system and surrounding components. These conditions, referred to as Acoustic Induced Vibrations (AIV), can lead to issues with leakage due to gasket and seal ruptures, valve failure, and in serious cases, fatigue and fracture of the piping system, related components and instrumentation. An example of such failure which had a great impact to Ontario Power Generation's (OPG) production was related to CANDU nuclear fuel bundle failures. In 1990, one of the fuel bundles in the Darlington nuclear power plant was damaged as a result of excessive vibration of the fuel elements. Therefore, the main objectives of this project are to experimentally investigate the effectiveness of passive acoustic damping devices on the attenuation of acoustic pressure pulsations in piping system and to numerically simulate the dynamic response of CANDU fuel bundle due to acoustic pressure pulsations. The gained knowledge from this research will provide practical design guidelines for implementation of new passive acoustic damping devices in piping systems to prevent the occurrence of acoustic pressure pulsations. Moreover, a more realistic three dimensional model for predictions of the fuel bundle vibration response to fluid excitations and acoustic pressure pulsations will be developed. This will not only support the increased safety and reliability of piping systems in nuclear power plants which will directly benefit the Canadian economy, but also could be used in future CANDU reactors to avoid fuel bundle failure due to the aforementioned excitation mechanism.