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调节阀振动问题在高参数汽轮机中普遍存在,已严重影响到机组运行的经济性和安全性。调节阀振动为复杂的流固耦合,依靠数值模拟揭示由流体诱发振动的原因逐渐成为重要的手段,但是目前针对调节阀的大部分数值模拟并未考虑阀杆系统振动对阀内流场的影响。该文在数值模拟中利用Fluent中动网格模块和UDF函数,对比分析了阀碟在静止和不同振幅、振动频率下对阀内流场的影响。在网格变形中使用了一种新颖的网格控制方法,即固定阀碟边界层网格使网格在较大尺度区域变形,确保了数值计算准确、顺利的进行。数值计算结果表明当阀碟顶端振幅小于0.6 mm时,阀碟上压力呈现随机波动;当阀碟顶端振幅为1mm时,阀碟上压力随阀碟移动出现明显的周期性波动,此时数值模拟应考虑阀杆系统振动的影响。随着振动频率的增加,阀碟上周期性的压力波动逐渐滞后于阀碟移动,当频率达到193.6 Hz时周期性波动消失。
The vibration problem of control valve is ubiquitous in high-parameter steam turbines, which has seriously affected the economy and safety of unit operation. Control valve vibration is a complex fluid-structure interaction. Relying on numerical simulation to reveal the reason of fluid-induced vibration gradually becomes an important method. However, most of the numerical simulations for the control valve do not consider the influence of the stem-system vibration on the flow field inside the valve . In the numerical simulation, Fluent neutral grid module and UDF function are used to analyze the influence of disc valve on the flow field in the valve under static and different amplitudes and vibration frequencies. A novel mesh control method is used in the deformation of the grid, that is, the grid of the boundary layer of the valve disc is fixed to deform the grid in a larger scale area, thus ensuring the accurate and smooth numerical calculation. The numerical results show that when the amplitude of the top of the valve disc is less than 0.6 mm, the pressure on the valve disc fluctuates randomly. When the amplitude of the top of the valve disc is 1 mm, the pressure on the valve disc shifts obviously with the disc movement. Shaft system should consider the impact of vibration. As the vibration frequency increases, the periodic pressure fluctuation on the valve disc gradually lags the valve disc movement, and the periodic fluctuation disappears when the frequency reaches 193.6 Hz.