CAP1400核主泵空化特性数值研究

针对CAP1400核主泵事故下的空化问题,在对核主泵进行水力设计及三维造型的基础上,采用CFD技术对核主泵的空化问题进行定常数值模拟,并分析了正常工况、空化初生、临界空化、严重空化和断裂空化等5个阶段核主泵叶片背面气相体积分数、叶片间气相体积分数及叶片间介质温度的分布特性.计算结果表明:核主泵空化首先发生于叶片背面靠近前盖板一侧并向叶片工作面、后盖板方向发展;临界空化与严重空化阶段气相体积分数在叶轮流道相对位置S=0.35~0.45时增长趋势相同,S=0.45~0.50时相对平缓;叶片间由于相变导致的两相之间的热传导在两相界面附近的液相中形成温度梯度,空泡内气相介质的温度低于附近液相介质的温度,两者温差随空化的发展而增大.

Numerical study on cavitation characteristics of CAP1400 nuclear main coolant pump

In order to study the cavitation problem of CAP1400 nuclear main coolant pump, the steady numerical simulation on the cavitation problem was conducted on the the basis of hydraulic design and three-dimensional modeling.The distribution characteristics of vapor volume fraction on the suction side of impeller blades, vapor volume fraction between blades and medium temperature between blades were acquired under the normal condition, incipient cavitation, critical cavitation, severe cavitation and fracture cavitation.The calculation results show that the nuclear main coolant pump cavitation occurs on the suction side of impeller blades first and develops in the direction of pressure side of blade and hub.Vapor volume fraction growth trend is the same from the relative position S=0.35-0.45, and vapor volume fraction is relatively smooth from S=0.45-0.50 in the impeller passage at the stage of critical cavitation and severe cavitation.Temperature gradient was formed in the liquid phase near the two-phase interface due to heat transfer between the two-phase caused by phase change.The vapor medium temperature inside the cavity is lower than the temperature of the liquid medium, and the temperature difference increases with the development of cavitation.