立式蜗壳泵轴承-转子系统瞬态动力学响应研究

Study on transient dynamic response of bearing-rotor system of vertical volute pump

为提高立式蜗壳泵的运行稳定性,数值模拟了泵内部流场,获得了不同工况下的径向力分布规律。利用"COMSOL"软件计算了"湿态"下泵轴承-转子系统瞬态响应,对比了单、双蜗壳模型泵转子的振动特性,计算了双蜗壳模型泵转子的振动位移、轴心轨迹,分析了小流量工况下导轴承油膜压力和厚度分布规律。结果表明:2种蜗壳型式下,叶轮承受的径向力均具有周期性,且随着偏离设计工况点,叶轮径向力逐渐增加;与单蜗壳模型泵相比,双蜗壳模型泵的径向力显著减小,转子振动减弱,在小流量工况下,转子在轴承处的振动峰对峰值降低了39.56%,叶轮振动总位移降低了15.17%,各个工况下,转子在导轴承处的振动峰对峰值均满足API标准的要求;"湿态"下转子系统的振动呈现周期性变化规律,转子在导轴承处的振动以半频为主,叶轮的振动以叶频为主;小流量工况下,导轴承内部油膜分布发生变化,油膜的四油楔分布导致了转子运行不稳定。

In order to improve the operational stability of vertical volute pump,the internal flow field of the pump was calculated by numerical simulation,and the distribution law of radial force under different working conditions was obtained.The"COMSOL"software was used to calculate the transient response of the bearing-rotor system of the pump under the"wet condition",the vibration performance of the single and double volute model pump rotor was compared,the vibration displacement and axis trajectory of the double volute model pump rotor was calculated,and the oil film pressure and thickness distribution law of the guide bearing under low flow rate condition was analyzed.The results show that the radial force of the impeller is periodic in both types of volute,and the radial force increases gradually with the deviation from the design condition.Compared with single volute model pump,the radial force of double volute model pump is significantly reduced,and the vibration of rotor is weakened.Under low flow rate condition,the bearing vibration peak-to-peak value of the rotor is decreased by 39.56%,and the total displacement of the impeller decreased by 15.17%.Under all working conditions,the vibration pea-peak value of the rotor at the guide bearing meet the requirements of API standard.Under the"wet state",the vibration of the rotor system presents a periodic variation,and the vibration of rotor in the guide bearing is dominated by half frequency,while that of impeller is dominated by blade frequency.Under the condition of low flow,the distribution of oil film inside guide bearing changes,and the distribution of four-oil wedge of oil film leads to unstable rotor operation.