带热套管的T型接管内流动换热的数值模拟和实验研究

Numerical and Experimental Investigation of Flow and Heat Transfer in a T-Junction with Thermal Sleeve

为了分析核反应堆冷却剂系统中带热套管T型接管内由于注入非等温横向射流导致的构件热冲击状况,本文应用计算流体力学商用软件FLUENT5.3进行了紊流流动换热的数值模拟,分析了主管及接管与热套管间环腔内的流动换热特性。针对套管上开有通流小孔,并采用凸台支撑的热套管结构形式,模拟了射流与主流流速比为0.05及0.5两种典型工艺。通过传热实验,研究了主管及接管内壁近壁区域的传热特性,并讨论了热套管尺寸变化对接管热冲击的影响。结果表明,数值模拟与实验数据吻合良好;热套管对构件的热保护程度与热套管结构形式及流速比密切相关;适当减小流速比有利于改善构件热应力状况。

Numerical simulations were performed with the commercial computational fluid dynamics(CFD)package FLUENT 5.3 to investigate the thermal-hydraulic phenomena of thermal shock,which is caused by non-isothermal turbulent jet into crossflow in a T-junction with thermal sleeve in the pressurized water reactor (PWR) cooling system.In allusion to the thermal sleeve configuration with vent holes and lower collar,two typical cases with jet-to-mainstream velocity ratios of 0.05 and 0.5 were computed.Experimental studies were carried out to determine the heat transfer characteristics for the main pipe and the annulus between the nozzle and the thermal sleeve.The calculations well matches the experimental data.The results indicated that the protective action of the thermal sleeve against thermal shock loading is dependent on both the sleeve geometry and the velocity ratio,obtaining improvement with appropriate lower velocity ratios.In addition,optimal flow rates and partial sizes of the thermal sleeve were discussed to reduce the thermal shock..