非均匀两相流传热管流致振动中阻尼模拟研究

在蒸汽发生器传热管流致振动分析时，由于传热管二次侧为汽水两相流，且空泡份额从下到上逐步增加，使得传热管上各位置的阻尼不同，需开展非均匀两相流中传热管的阻尼模拟研究。使用Pettigrew的两相流中管阻尼公式，结合典型实例中空泡份额沿传热管分布情况开展后续分析。传热管阻尼中的两相阻尼分量，分析了常用工程软件空泡份额处理方法阻尼高估的弊端，原因在于空泡份额影响系数的非线性。引入分段加权的方法，研究了不同分段长度的影响，表明应尽量减小分段长度。针对后续的分段（非均匀）阻尼加权等效问题，对比了工程方法和规范中不同加权因子的影响，彼此差异较小。开展了不同阻尼输入的流致振动分析结果比较，判断Pettigrew阻尼公式的适用性。由上述4个问题的研究给出推荐的非均匀两相流中传热管阻尼模拟方法，以更准确地开展传热管流致振动分析。 

Study on Flow-Induced Vibration Damping Simulation of Heat Exchanger Tube in Non-Uniform Two-Phase Flow

In the flow-induced vibration analysis of the heat exchanger tube of the stream generator, the damping of each position on the tube is different, since the secondary side of the tube is the two-phase flow (stream-water) and the void-fraction is gradually increased from bottom to top. It is necessary to study the simulation of the tube damping in non-uniform two-phase flow. The study is based on the Pettigrew's damping formula of tube in two-phase flow and the void-fraction distribution along the tube in the typical example. For the two-phase damping component of the tube damping, the disadvantage of damping overestimation of void-fraction processing method in common engineering software are analyzed. The reason is the nonlinearity of the void-fraction influence coefficient. The method of segmentation weighting void-fraction is developed. The effects of different segment lengths are studied, indicating that the section lengths should be minimized. For the subsequent segmentation damping weighting problem, the effects of different weighting factors in engineering methods and standards are compared, and the difference is small. The results of flow-induced vibration analysis with different damping inputs were compared to judge the applicability of Pettigrew's damping formula. From the above four researches, the recommended simulation method of the tube damping in non-uniform two-phase flow is given to more accurately carry out the flow-induced vibration analysis of heat exchanger tube.