【作者】 黄波；

【导师】 龚圣捷；

【作者基本信息】 上海交通大学 ， 核能与核技术工程（专业学位）， 2020， 硕士

【摘要】 压水核电站主管道使用破前漏(LBB)分析技术,可以降低系统管道复杂性,提高核电厂的安全性以及经济性,其中准确估计冷却剂通过贯穿裂纹的泄漏率是保证LBB分析技术成功的重要环节。由于压水堆主管道内外巨大的压差作用,高压过冷水通过贯穿裂纹的泄漏会发生临界流动,早期的实验多针对尺寸较大的圆管结构开展相关机理研究,缺乏狭缝结构的临界流动实验数据,而理论模型计算也未能对上游过冷的临界流动物理现象做完整描述,基于经典模型建立的仿真计算程序也无法对该问题进行准确模拟。开展高压过冷水通过缝隙的流动实验并改进相关计算模型对于LBB分析的工程应用有重要意义。本文将主管道贯穿裂纹简化为矩形狭缝流道,搭建了高压过冷水临界流动实验台架,开展了上游过冷条件下100×10×0.6 mm~3、50×7×0.4 mm~3、100×10×0.3 mm~3三种不同尺寸的矩形狭缝临界流动实验研究,上游压力范围4～12 MPa,上游温度范围186～265℃,获得大量可靠的实验数据。对比了不同的两相临界流动计算模型,Henry-Fauske模型更适用于上游高压过冷水通过狭缝的两相临界流动计算,针对实验观察到的热力学不平衡现象,利用计算精度更高的Jones-Alamgir-Lienhard闪蒸公式改进了模型计算。最后综合实验结果和模型计算结果,分析上游流体参数以及狭缝结构参数对临界流动特性的影响。研究表明:1)临界流量随着上游压力的增大、温度的降低而逐渐增大,临界压比越小;2)闪蒸起始点位置随着上游过冷度的降低从出口向上游逐渐移动,对临界流量计算影响很大;3)改进的模型可以很好地预测闪蒸起始点位置和闪蒸压力,预测临界流量的精度为-5%～+15%,临界压力精度为-10%～+15%;4)在典型压水堆工况下,更小的间隙尺寸、更长的流动长度以及更大的粗糙度会得到更小的临界泄漏流量,而入口形阻系数大小对流量的影响不是很明显。更多还原

【Abstract】 The use of leak before break(LBB)analysis technology in pressurized water reactor primary pipe can reduce the complexity of pipeline systems,which greatly improve the safety and economics of nuclear power plants.And how to accurately predict the flowrate of coolant through a crack in pipeline is the key to achieve the LBB analysis technology successfully.Because of the huge pressure difference between the inside and outside of the pipe,the leakage of high-pressure subcooled water through the crack will induce critical flow,however early experiments mostly focused on large scale circular tube structures,and paid less attention on narrow slits,neither classical theoretical models nor the simulation program based on these models fail to fully predict this kind of physics phenomenon.Therefore,it is of great significance for the engineering application of LBB analysis to carry out high pressure subcooled water flow experiments through slits and improve the relevant calculation model.In this paper,the wall-through crack was simplified into a narrow rectangular flow channel,and a high-pressure subcooled water critical flow experimental test facility was set up.A large amount of reliable critical flow data with test section sizes of 100mm×10mm×0.6mm、50mm×7mm×0.4mm and 100mm×10mm×0.3mm was obtained,under the upstream pressure range of 4～12MPa,the upstream temperature range of186～265℃.Compared with different two-phase critical flow calculation models,the Henry-Fauske model is more suitable for the two-phase critical flow calculation of upstream high-pressure subcooled water through narrow slits.In view of the observed thermodynamic non-equilibrium phenomenon,the Jones-Alamgir-Lienhard formula with higher accuracy in calculating flashing was used to improve the Henry-Fauske model calculation.Finally,the experimental data and model calculations results were combined to analyze the influence of upstream fluid parameters and slit structure parameters on critical flow characteristics.The main conclusions are as follows:1)With the increasing of upstream pressure and the decreasing of upstream temperature,the critical flowrate increases,at the same time the critical pressure ratio decreases.2)The location of flashing inception moves from exit to the upstream direction with the decrease of upstream subcooling,which has a great impact on critical flowrate.3)The improved model can well predict the location and pressure of flashing inception,and the predicted critical flowrates and critical pressures have a good agreement with experimental data with an error range of-5～+15%and-10～+15%;4)Under typical PWR conditions,a smaller silt opening size,longer flow length and greater roughness result in a smaller critical leakage flowrate,while the effect of entrance resistance factor on the flowrate is not such obvious.更多还原