摘要
为了解某核电站汽轮机主调阀在小开度下大幅震颤的机理,通过瞬态数值模拟计算,分析在小开度下阀门压比逐渐降低时阀腔内气流流动结构变化以及阀芯和管道处压力波动脉动频谱的特性。结果表明:阀门小开度大压比工况下,蒸汽为附壁流动,壁面气流脉动幅值极低,阀芯与管道壁面处气流脉动力最大幅值小于100 N。当压比降低到临界分离压比以下时,蒸汽射流呈现出一侧分离、另一侧附壁的流动状态,且两侧射流均在附壁和分离状态之间不断交替,这种流动状态极不稳定;斯特劳哈尔数在0.6~0.8区间时,阀芯气流脉动力存在幅值达2 500 N的宽频脉动;脉动频率在400~600 Hz区间时,管道气流脉动力存在幅值达9 000 N的宽频脉动。当压比继续降低到一定程度后,气流经过阀芯喉部后可以形成相对稳定的分离射流状态,阀芯气流脉动力最大幅值仅为临界分离状态的30%左右,而管道气流脉动力主频从宽频向单一频率变化,且幅值迅速增大至临界分离状态的2倍以上。
In order to understand the mechanism of large tremor in the main valve of steam turbine in a nuclear power plant under small opening,the change of air flow structure in the valve chamber and the characteristics of pressure fluctuation spectrum in the valve core and pipeline were analyzed by transient numerical simulation when valve pressure ratio gradually reduced under small opening.The results show that under the condition of small valve opening and large pressure ratio,the steam is attached to the wall,the amplitude of air flow pulsation on the wall is very low,and the maximum amplitude of air flow pulse force between the valve core and the pipe wall is less than 100 N.When the pressure ratio is reduced be-low the critical separation pressure ratio,the steam jet presents a flow state of separation on one side and attachment on the other side,and the jets on both sides are constantly alternating between attachment and separation states.This flow state is extremely unstable.In the Strouhal number range of 0.6 to 0.8,the air flow pulse force in valve core has a wide frequency pulsation with a amplitude of 2500 N.In the pul-sation frequency range of 400 to 600 Hz,air flow pulse force in pipeline has a wide frequency pulsation with amplitude of 9000 N.After the pressure ratio continues to decrease to a certain extent,the air flow through the valve core throat can form a relatively stable separation jet state,and the maximum value of the valve core air pulse force is only about 30%of the critical separation state,while the main frequency of the pipeline air pulse force changes from wide frequency to a single frequency,and the amplitude rapidly increases to more than 2 times of the critical separation state.
作者
侯章瑛
何峥梁
殷海东
黄典贵
HOU Zhangying;HE Zhengliang;YIN Haidong;HUANG Diangui(School of Energy and Power Engineering,University of Shanghai for Science and Technology,Shanghai,China,200093)
出处
《热能动力工程》
CAS
CSCD
北大核心
2024年第10期94-101,176,共9页
Journal of Engineering for Thermal Energy and Power
基金
上海市科学技术委员会项目(22010503100)。
关键词
核电汽轮机
调节阀
流场
压力脉动
频率特性
nuclear power turbine
control valve
flow field
pressure fluctuation
frequency characteristic
