PTS瞬态流动与换热数值模拟研究

Numerical Investigation of PTS Transient Flow and Heat Transfer

为了研究压水堆因“直接安注”冷水注入压力容器下降环腔而导致的承压热冲击（PTS）热工水力问题,基于1:10比例模型,应用计算流体力学软件FLUENT5.4进行了紊流流动换热的数值模拟分析,同时进行了常压瞬态传热实验研究。针对下降环腔折算流速0.5 m/s,安注流速10m/s的典型工况,研究了安注水开启后下降环腔内的瞬态流动换热特性,数值模拟与实验结果吻合良好。考察了压力容器安注接管出口区环形焊缝区及堆芯段筒体中子强辐照区所承受的热冲击状况,基于稳态流动研究了下降环腔内流体混合特性及流动机理,为热冲击分析提供参考。

Using the commercial fluid dynamic, software FLUENT 5. 4, combined with the heat transfer experiments based on the 1 : 10 setup at ambient pressure, numerical simulations were performed to investigate the thermal-hydraulic phenomena of the pressurized thermal shock (PTS), which is caused by the cold safety injection(SI)fluid directly into the reactor pressure vessel (RPV) in the pressurized water reactor (PWR). Transient flow and heat transfer characteristics were analyzed once the SI system was started in the typical operation condition of the superficial velocity in the downcomer 0.5m/s and the SI velocity lOm/s.The calculations well matchthe experimental data. The thermal shock on the pressure vessel was examined in the region of the SI nozzle corner, the circumferential weld and the core beltline suffering relatively high neutron irradiation. The mixing behavior and flow mechanism of fluid in the downcomer were studied based on the steady flow. The results may be used for further thermal shock analysis.