共查询到14条相似文献,搜索用时 85 毫秒
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低压低干度自然循环流量漂移分析 总被引:1,自引:0,他引:1
在 5MW核供热堆全尺寸全参数模拟试验回路HRTL 5上进行的实验中 ,观察到在一定条件下系统发生静态流量漂移的同时 ,伴随动态流量振荡。本文总结了HRTL 5模拟试验回路上的实验研究结果 ,分析了低压低干度自然循环系统的特点、欠热沸腾和闪蒸的作用机理 ,较完整地描述了自然循环流量漂移的整个过程。分析结果表明 :1 )在自然循环系统中 ,欠热沸腾和闪蒸对流动稳定性具有重要作用 ;2 )自然循环流量漂移是一个长热工过程 ,动态振荡也可以发生在静态流量漂移过程中 ;3 )在静态流量漂移的发生、发展并向动态振荡转变的过程中 ,先是欠热沸腾占主导地位 ,然后逐渐转变为闪蒸占主导地位 ,最后主要表现为密度波振荡的形式。自然循环流量漂移对 5MW堆的设计、安全分析以及升级开发具有重要价值。 相似文献
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低干度自然循环流量漂移的特征曲线图谱分析 总被引:1,自引:0,他引:1
在5MW低温核供热堆全模拟试验回路(HRTL-5)上,实验观察到了低干度自然循环条件下的流量漂移现象.通过一个考虑了加热段欠热沸腾、上升段冷凝、闪蒸等物理过程的两相流动数学模型,编制了相应的计算程序,获得了自然循环特征曲线图谱及其运行曲线,确定了自然循环分岔图和静态不稳定边界图,进而提出了通过自然循环特征曲线图谱研究流量漂移的分析方法.分析表明:特征曲线图谱方法是研究自然循环静态不稳定的有效手段.增大系统压力、减小热流密度、增加入口单相阻力、减小出口两相阻力有利于避免自然循环流量漂移的发生. 相似文献
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在 5MW核供热堆试验回路HRTL 5上观察到了一定条件下系统发生的静态流量漂移并同时伴随动态流量振荡的现象。本文在实验基础上 ,研究了流量漂移的发生、发展和向动态振荡演变的过程 ,以及欠热沸腾、冷凝、闪蒸在此过程中的作用机理。分析结果表明 :1 )自然循环流量漂移是一个长热工过程 ,动态振荡可发生在静态漂移过程中 ;2 )在流量漂移的过程中 ,先是欠热沸腾和冷凝占主导地位 ,然后渐变为闪蒸占主导地位 ,最终表现为自持振荡形式 ;3)最终的自持振荡主要表现为密度波振荡 ,又具备喷泉不稳定的特征。 相似文献
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基于一维两相四方程漂移流模型,采用数值模拟的方法对5MW低温核供热堆热工水力模拟回路(HRTL-5)的自然循环稳态特性进行模拟,分析了HRTL-5自然循环流量特性及其参数效应。结果表明:1)漂移流模型比均相流模型更适用于HRTL-5;2)当系统压力为1.5MPa时,系统自然循环流量随加热热流密度的升高而增加;3)当系统压力为0.5MPa时,系统自然循环流量随加热热流密度的升高先增加后减小;4)自然循环流量随加热段入口欠热度的升高而减小;5)当加热热流密度较低时,〖JP3〗系统自然循环流量随压力的升高而减小,当加热热流密度较高时,系统自然循环流量随压力的变化呈现复杂状况。 相似文献
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An experiment was performed on the test loop (HRTL-5), which simulates the geometry and system design of a 5-MW nuclear heating reactor. In a wide range of inlet subcoolings, different flow modes, such as single-phase stable flow, subcooled boiling stable flow, subcooled boiling static flow excursion, density-wave oscillation and stable two-phase flow in the natural circulation system have been described. The phenomenon and mechanism of the static flow-excursion, which has never been studied well on this field, is especially interpreted. The experimental results show that, in the process of flow excursion, the mass flow rate and the inlet temperature decreases, while the exit temperature increases smoothly. As the process of the excursion continues for about 1 h, short period dynamic flow oscillation occurs, which can only be seen in the process of this static flow excursion, and has also never been studied well. These static and dynamic flow instabilities combine together and continue for about 2 h, then a point is reached, at which the static flow excursion disappears, but the dynamic flow oscillation continues. The mechanism of the static flow excursion is interpreted through two sets of curves for flow resistance pressure drop and driven head in natural circulation, and one curve for the natural circulation operation under special thermohydraulic condition. The study of the flow excursion and its concerned dynamic flow oscillation is of great significance for the development of the nuclear heating reactor under natural circulation. 相似文献
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Best Estimate computer codes have been, so far, developed for safety analysis of nuclear power plants and were extensively validated against a large set of separate effects and integral test facilities experimental data relevant to such kind of reactors. Their application to research reactors is not fully straightforward. Modelling problems generally emerge when applying existing models to low pressure and more particularly to subcooled flow boiling situations. The objective of the present work is to investigate the RELAP5/3.2 system code capabilities in predicting phenomena that could be encountered under abnormal research reactor’s operating conditions. For this purpose, the separate effect related to the static onset of flow instability is investigated. The cases considered herein are the flow excursion tests performed at the Oak Ridge National Laboratory thermal hydraulic test loop (THTL) as well as some representative Whittle and Forgan (W & F) experiments. The simulation results are presented and the capabilities of RELAP5/Mod 3.2 in predicting this critical phenomenon are discussed. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(3):312-314
An experiment was performed on the natural circulation test loop HRTL-5, which simulates the geometry and system design of the 5 MW full power natural circulation nuclear heating reactor. Different flow modes, including density wave oscillation and flow excursion et al., were observed in a wide range of inlet sub-cooling at 1.5MPa. By means of self-developed computational codes, the bifurcation chart has been obtained. Consequently the flow excursion boundary has been determined. Through the analysis on the excursion boundary, the method to avoid the flow excursion during startup has been presented. Analytical results show: (1) with the decreasing heat flux or the increasing system pressure, the static flow excursion occurs at higher inlet temperature and its range in the instability maps becomes narrower correspondingly; (2) to decrease the outlet two-phase resistance or increase the inlet single-phase resistance is beneficial to avoid the flow excursion; (3) by means of increasing the system pressure to start up the reactor with low heat flux, the flow excursion and low steam quality density wave oscillation can be successfully avoided. This investigation is meaningful to the reactor safety and the design of the nuclear heating reactors. 相似文献