LNG超低温调节阀阀杆流激共振分析

针对LNG接收站超低温调节阀小开度下阀杆流激共振问题,以DN200-Class600 LNG超低温调节阀5%、10%、20%、30%和50%开度的模型为研究对象。采用Fluent软件对各模型进行瞬态流场分析,并对阀塞和阀杆组件流固耦合面上的流体压力脉动时域信息进行监测,通过Tecplot软件对监测信息进行快速傅里叶变换(FFT),获得流体施加于阀杆上的激振力频率。另外采用ANSYS Workbench软件对各模型进行流固耦合模态分析,得到阀塞和阀杆组件的流固耦合模态振型和模态频率。通过两种频率的比较对各开度下的调节阀阀杆流激共振问题进行了深入研究。结果表明,调节阀各开度下阀塞和阀杆组件上的压力脉动峰值频率均在60 Hz以内,而其各阶流固耦合模态频率均大于120 Hz,压力脉动频率避开了固有频率,阀杆不会发生流激共振现象。

Flow-inducedresonance analysis of valve stem for LNG ultra-low temperature control valve

Aiming at the problem of flow-induced resonance of valve stem under small opening of an ultra-low temperature control valve in LNG terminal,models under 5%,10%,20%,30%and 50%openings,respectively of DN200-Class600 LNG ultra-low temperature control valve were taken as study objects.The software Fluent was used to do transient flow field analysis of each model,and monitor fluid pressure fluctuation time-domain information on the fluid-solid coupled surface of valve plug and valve stem assembly.The software Tecplot was used to do fast Fourier transformation(FFT)of the monitored information,and obtain exciting force frequencies exerted on valve stem by fluid.In addition,the fluid-solid coupled modal analysis of each model was performed with the software ANSYS Workbench to obtain fluid-solid coupled modal shapes and modal frequencies of valve plug and valve stem assembly.The flow-induced resonance of the valve stem under each opening was studied deeply by comparing the two kinds of frequencies.The results showed that pressure fluctuation peak value frequencies on valve plug and stem assembly under each opening of the control valve are all within the range of less than 60Hz;their various fluid-solid coupled modal frequencies are larger than 120 Hz;pressure fluctuation frequency avoids natural frequency,and valve stem does not produce flow-induced resonance.