中文摘要：

为研究小破口失水事故工况下余热排出泵内部空化流动特性,基于Rayleigh-Plesset方程的混合物均相流空化模型和剪切应力运输SST湍流模型,对余热排出泵高温高压环境下叶轮内空化流动进行全流道数值计算。根据计算结果获得了余热排出泵小破口严重事故工况下扬程和效率的衰减曲线及空化发生的初始压力,捕捉到泵内空化的发生、发展过程。研究结果表明：当环境压力降低至大约1.15 MPa时,叶片吸力面进水边靠近前盖板处开始出现空泡,随着环境压力的降低,空泡分布区域及空泡体积分数不断扩大;当压力降低至1.143 MPa时,叶轮内部最大空泡体积分数达到50.17%,严重空化时,叶片工作面会有空泡聚集并造成叶轮流道严重堵塞致使泵扬程急剧下降。通过分析空化发生的状况得出空化发生的初始压力,为余热排出泵的设计提供一定的参考。

英文摘要：

In order to investigate the internal cavitating flow characteristics of residual heat removal pumps during the small break loss of coolant accident（ SBLOCA）,the three-dimensional cavitating flow under high temperature and high pressure within the whole flow passages of a residual heat removal pump was simulated using the homogeneous mixture cavitation model based on the Rayleigh-Plesset equations and the shear stress transport（ SST） turbulence model. The attenuation curves of head and efficiency and critical cavitation environmental pressure during the SBLOCA were obtained from the simulation results. The cavitation inception and development were captured as well.The simulation results showed that the vapor appears first on the suction surface of blades near the front shroud when the environmental pressure decreases to 1.15 MPa or so. The cavitation area and water vapor volume fraction increase gradually with the decrease of environmental pressure. The maximum water vapor volume fraction increases to 50.17% as the environmental pressure drops to 1.143 MPa. Moreover,the vapors appear on the pressure surface of blades and the serious blockage due to cavity in the flow passages results in a sharp drop in the pump head and reliability under severe cavitation condition. The given results about the cavitation characteristics and the derived critical cavitation environmental pressure are useful for the design of residual heat removal pumps.