针对某超(超)临界火电机组主给水调节阀在运行过程中出现的空化汽蚀现象,结合多级节流原理和多相流技术,利用CFX流体力学计算软件,对调节阀内部流场进行模拟,分析不同笼罩级数和节流孔个数对空化流场的影响.结果表明:多级笼罩结构使得阀内最低压力由3.55 MPa升至6.58 MPa且高于空化压力,汽相最大体积分数从0.96几乎降为0,整体流场速度明显降低,有效防止了空化汽蚀对调节阀的破坏;同时,在满足调节阀工况的前提下,增加节流孔数会使降压性能提高,但却使流速控制能力降低.%Aiming at solving the problem of control valve cavitation damage in main feed system of ultra-supercritical thermal power units,this paper carried out numerical simulation on internal flow field of the control valve,by combining with multistage throttle theory and multiphase flow technology,and using the computational fluid dynamic software CFX.The influence of shroud stage and ring hole on the control valve's cavitation flow field was studied.The results show that,due to the multistage shroud structure,the minimum pressure inside the control valve rises from 3.55 MPa to 6.58 MPa and is higher than the cavitation pressure,and the maximum vapor fraction reduces from 0.96 to almost zero.The velocity of the whole flow field reduces obviously,so the damage of the control valve caused by cavitation can be effectively prevented.Moreover,on the premise of satisfying the operating conditions of the control valve,increasing the throttle hole number will leading to opposite effects on the pressure reduction and velocity control.
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