蒸汽发生器传热管湍流激励功率谱密度计算

Power Spectrum Density Calculation of Turbulent Excitation about Steam Generator Tubes

湍流激励是核蒸汽发生器换热管发生流致振动的重要机理之一,也是微振磨损的重要诱因。为计算换热管的微振磨损速率,需要首先获得湍流激励功率谱密度(PSD),其此前只能通过试验的方法获取。为利用CFD方法获得换热管上的湍流激励功率谱密度,建立了蒸汽发生器换热管束流场的数值模型,基于LES方法计算得到了管束内部的流场分布,提取了传热管上所受流体力并计算得到了其功率谱密度,计算结果与试验结果吻合良好。结果显示,管束内部传热管所受流体力为具有尖峰特征的宽频信号,其能量集中在一定带宽内。其结果为利用CFD方法计算传热管微振磨损建立了基础。

Turbulent excitation is one of the flow - induced vibration mechanisms in steam generators, and also is the principal motivation of the tube fretting wear. To calculate the volume wear rate of tubes, power spectrum density （PSD） of turbulent excitation is necessary, which usually was obtained from experiment. To obtain the PSD of turbulent excitation based on CFD method, the numerical model of tube arrays was modeled, and the flow distribution in tube arrays was obtained based on the LES method, the flow - in- duced forces applied on the tube were saved and the PSD of the forces was calculated. The results showed that, the flow -induced forces applied on the tubes are broadband excitation with peak value characteristic, and the power of the forces was limited in certain frequency band. The results indicate a new method to obtain the PSD of turbulent excitation, which can significantly increase the efficiency of fretting wear analysis.