表面张力对大尺寸支管夹带的影响研究

The previous research of entrainment through a small break cannot be applied for entrainment through a large size branch, thus the research of entrainment through a large size branch is necessary. The existing theory of entrainment through a large size branch inheriting ideology of small break entrainment theory still ignores the effect of surface tension in the modeling analysis. However, for a large branch entrainment phenomenon, experimental studies showed that the gas Froude number in branch was always small, even less than 1 so that the effect of surface tension on entrainment could not be ignored. In this project, an experimental facility referring to Fourth Stage Automatic Depressurization System (ADS-4) in AP1000 will be built for the research of liquid entrainment through a large size branch using air-modified water as medium. The previous experimental data and models are summarized and sorted. Effect of surface tension on onset entrainment, stable entrainment and flow regime of entrainment is studied. Also, surface tension is considered in the modeling analysis to develop a more extensively applicable scope and more accurate entrainment model. The research is meaningful for the design of AP1000 and CAP1400 and can offer important data and model references for China software with independent intellectual property rights.

早期T型管夹带研究主要关注主管小破口夹带现象，其理论已不适用于大尺寸支管夹带现象，故需要研究大尺寸支管夹带所涉及的科学问题。然而现有大尺寸支管夹带理论多是忽略表面张力对夹带的影响。近年来实验发现大尺寸支管夹带发生时，支管气相Fr数较小，甚至小于1，此时基于忽略表面张力的理论模型是不准确与不恰当的。本项目拟以AP1000中第四级自动泄压系统管线夹带为背景，利用空气-改性水为工质进行大尺寸支管液相夹带试验研究，并整理归纳早期空气-水与蒸汽-水夹带试验数据与理论，探讨工质表面张力对夹带起始点、稳态夹带过程以及夹带流型转变的影响规律及机理。在此基础上，建立基于表面张力的液滴脱离理论模型，力求建立一个适用范围更广且更加准确的T型管夹带预测模型。本研究可为我国具有自主知识产权的安全分析软件以及AP1000、CAP1400或未来核电厂设计中所涉及的T型管夹带现象的分析与验证提供数据与模型支持。

本项目以核电厂LOCA事故后存在的T型管夹带现象为背景，针对现有相关研究仅考虑惯性力与重力对夹带的影响，而忽略表面张力对夹带影响这一科学问题，开展多工质夹带影响试验与理论研究。在试验研究中，主要探讨不同工质的表面张力对夹带现象的影响规律与机理，获得T型管夹带影响因素数据库。并且通过可视化研究，探讨表面张力对夹带现象的作用机理。在夹带的理论建模分析中，结合可视化研究中得到的表面张力对液滴的作用机理，对夹带过程进行合理化假设，考虑表面张力对液滴脱离的作用，建立全新的夹带预测模型，并对新模型的适用性进行了全面的对比分析，进而获得了适用范围更广且精度更高的夹带预测模型。本项目的研究成果可为大型先进压水堆AP1000、CAP1400以及未来核电厂设计与安全分析中所涉及的T型管夹带现象分析与模拟提供数据与理论支持，同时也可为具有我国自主知识产权的核电安全分析软件中所涉及的夹带现象的程序建模与验证提供理论与数据支持。