安装状态对汽机旁路阀固有频率的影响

Influence of Installation State on Natural Frequency of Turbine Bypass Valve

为研究安装状态对汽机旁路阀固有频率的影响规律,根据双梁结构假设和欧拉-伯努利梁理论,建立热态全流量试验管线中汽机旁路阀的横向振动分析模型;基于扫频法和敲击法,分别搭建振动测试平台,测试汽机旁路阀在本体刚性支撑和管线支撑2种安装状态的固有频率;采用ANSYS软件的流固耦合和模态仿真模块,求解实际工况参数下不同管线支撑距离的汽机旁路阀固有频率。研究表明:采用扫频法、敲击法和数值模拟方法获得本体刚性支撑的汽机旁路阀最小固有频率分别为34.5、35、35.41 Hz,符合核电阀门抗震频率要求;管线支撑使汽机旁路阀刚性变弱,固有频率降低约7 Hz;管线支撑位置与汽机旁路阀本体距离越远,固有频率下降程度越大;蒸汽介质与汽机旁路阀的流固耦合作用使固有频率降低。汽机旁路阀实施振动抑制措施时,应避免接近实际安装状态的固有频率及其倍频,亦可调整管线支撑与阀门距离增加或减小固有频率,从而实现有效抑振。

In order to study the influence of the installation state on the natural frequency of the turbine bypass valve,a lateral vi⁃bration analysis model of the turbine bypass valve in the thermal full-flow test pipeline was established according to the double-beam structure assumption and the Euler-Bernoulli beam theory.Based on the sweep frequency method and the simple percussion method,a vibration test platform was built respectively to test the natural frequency of the turbine bypass valve in the two installation states of the rigid support of the body and the support of the pipeline.The fluid-structure interaction and modal simulation modules of ANSYS software were used to solve the natural frequencies of the turbine bypass valve for different pipeline support distances under the actual operating parameters.The research shows that the minimum natural frequencies of the turbine bypass valve with rigid support of the body acquired by the frequency sweep method,the simple percussion method and the numerical simulation method are 34.5 Hz,35 Hz and 35.41 Hz respectively,which meet the seismic frequency requirements of nuclear power valves.Pipeline support weakens the stiffness of the turbine bypass valve,which in turn reduces the natural frequency by about 7 Hz.The farther the pipeline support posi⁃tion is from the turbine bypass valve body,the greater the reduction is in natural frequency.The fluid-structure interaction effect of steam medium and turbine bypass valve reduces the natural frequency.Vibration suppression measures for turbine bypass valve should avoid the natural frequency and its multiplier close to the actual installation state,and the distance between the pipeline support and the valve can also be adjusted to increase or decrease the natural frequency,so as to achieve effective vibration suppression.