低压、低含汽量蒸汽-水两相临界流

STEAM-WATER TWO-PHASE CRITICAL FLOW AT LOW PRESSURES AND LOW QUALITIES

一、引言 两相临界流研究高温、高压系统破口事故时,汽(气)-液两相流体的最高排放速度,是核电安全中的重要课题。由于两相流动的复杂性,两相临界流理论还没有到成熟阶段。不同试验者的数据,尤其是在低含汽量(x【0.02)时相差较大。

Two-phase steady-state critical flow conditions at low pressures and low qualities were obtained with a closed loop. Mass flow-rates, inle temperatures and pressures, axial pressure and void fraction distributions were measured for 104 critical flow conditions, of which the parameter ranges were: throat pressues 0.36-0.52 MPa, throat qualities 0.01-0.018. A thermal non-equilibrium coeficient, Nt=24xEt, according to Henry's theory, was obtained with the measured data of void fractions at throat. A homogeneous non-equilibrium model is proposed for critical flows at low pressures and low qualities. With given inlet pressures and temperatures, the model predicts axial pressure distributions under critical flow conditions satisfactorily, predicts critical mass flow rates about 18% lower than measured values.