横掠管束的两相流湍流激振力的包络谱研究

Research on Upper Bound of Buffeting Force Caused by Two-phase Flow across Tube Bundle

蒸汽发生器等换热器中存在大量受两相流冲刷的管束结构。计算两相流湍流导致的管束振动响应时,需先确定流体激振力的功率谱密度(PSD)。由于缺乏有公认合理的两相流激振力的无量纲归一化方法,从而导致没有可供工程应用的两相流激振力的PSD包络谱。本文通过修改de Langre无量纲归一化方法中的混合物流速定义,获得1组新的两相流激振力PSD的包络谱。通过将本文包络谱与基于单相流的包络谱和de Langre包络谱的对比,并针对非均匀横向两相流作用下的蒸汽发生器U型传热管,计算了3种包络谱作用下的湍流激振响应。结果表明,基于单相流激振力PSD包络谱作为输入计算两相流湍流激振响应并不保守,而本文包络谱在保证安全性的前提下适当降低了de Langre包络谱过高的保守性。

There are many tube bundles subjected to two-phase cross flow in heat exchangers, such as steam generators. For calculating the vibration response of tube bundles caused by two-phase flow turbulence, the power spectrum density （PSD） of buffeting forces should be obtained firstly. Since there is no generally accepted method for normalizing the buffeting forces, the acknowledged upper bound of buffeting forces caused by two-phase flow is absent. By modifying the definition of mixture velocity used in the de Langre＇s nondimensional normalizing procedure, a new set of upper bound of buffeting forces caused by two-phase flows was obtained. The new upper bound was compared with the one based on single-phase flow and de Langre＇s upper bound. Through a sample of steam generator tube subjected nonuniform two-phase cross flow, the random vibration responses were calculated with the three types of upper bounds.The results show that the upper bound based on single-phase flow is not conservative as the input for calculating the vibration response excited by two-phase cross flow, and the new upper bound reduces the excessive conservatism of de Langre＇s bound in the prem- ise of ensuring the safety.