基于壳侧流场的电站凝汽器冷却管汽流激振评估的数值模拟

Numerical simulation on evaluation of steam-flow exciting vibration of cooling pipe of power unit condenser based on flow field of shell side

为了更好地评估凝汽器冷却管的汽流激振情况,提高电站凝汽器的安全保障,采用数值模拟方法,对凝汽器喉部和壳侧分别进行蒸汽流动的模拟,其中壳侧蒸汽流动的模拟以喉部出口流场作为入口条件,基于凝汽器壳侧流场分布计算了用于判别汽流激振的参数—临界横流速度和风险系数,从而完成对冷却管汽流激振的评估研究。对某凝汽器模拟研究结果表明:该凝汽器两侧上方“树枝”间管束模块外围冷却管处汽流激振的风险系数约为1.2,存在很大的汽流激振可能性,所评估的汽流激振位置与该凝汽器冷却管振动失效位置有一定的吻合度。该方法可以在管束横截面上对凝汽器冷却管进行更具体细致的评估。

In order to better evaluate the steam-flow exciting vibration of cooling pipe and improve the safety guarantee of power unit condenser, the steam flow in the throat and on the shell side of the condenser is numerically simulated respectively. The steam flow on the shell side was simulated with the outlet flow field of the throat as the inlet condition. Based on the distribution of the flow field on the shell side of the condenser, the critical cross velocity and risk coefficient are calculated to distinguish the steam-flow exciting vibration, so as to complete the evaluation of the steam-flow exciting vibration of the cooling pipe. The simulation results show that, the risk coefficient of steam-flow exciting vibration at the peripheral cooling pipe of the “tree” bundle module above both sides of the condenser is about 1.2, indicating there has a great possibility of steam-flow exciting vibration. The evaluated steam-flow exciting vibration position is consistent with the vibration failure position of the condenser cooling pipe. This method can make a more specific and detailed evaluation of the condenser cooling pipe on the cross section of the tube bundle.