共查询到18条相似文献,搜索用时 218 毫秒
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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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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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两相自然循环非能动系统静态分岔特性和参数效应研究 总被引:1,自引:0,他引:1
耗散结构在流体动力学中存在,两相自然循环非能动系统稳定性是耗散结构在多相流体动力学中的问题,运用分岔理论及其DERPAR数值方法给出系统随参数变化的演化过程的静态分岔解图图谱。以静态分岔解图呈现的迟滞现象(多平衡解)定义了输热能力限、静态漂移稳定性准则、稳定性裕度、比质量流量输热能力、分岔现象消失—呈单值性的临界参数区的系统演化的自组织特性的物理本质—系统的稳态和时间相关态随着特征参数的演化。用低压下的实验数据与理论计算分析进行比较,变化趋势吻合,尚需进一步验证。 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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《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
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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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Flow excursion was observed on the natural circulation test loop HRTL-5, which simulates the geometry and system design of the 5 MW nuclear heating reactor. By means of self-developed computational codes, a set of tools used for analyzing the flow characteristics of the natural circulation have been presented, including the characteristic curves, operational curve and the bifurcation curve. The two-dimensional disturbance analysis is adopted to explain the mechanism of the flow excursion. Analytical result shows: (1) flow excursion can occur in a natural circulation system at a suitable geometry and thermal–hydraulic conditions. (2) Characteristic curves, operational curve, bifurcation curve, and the two-dimensional disturbance analysis are the available method to analyze the flow excursion of the natural circulation. (3) The flow excursion is prior to the low steam quality density wave oscillation. (4) The onset of the flow excursion is the tangency point of the drive force curve and the flow resistance curve. (5) To operate at low heat flux to increase the inlet temperature is the effectual approach to transfer from the pressurized water state to the boiling water state, in which the flow excursion and the low steam quality density wave oscillation can be avoided. 相似文献
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In order to study the two-phase natural circulation and flow termination during a small break loss of coolant accident in LWR, a hot leg U-bend simulation loop has been built based on the two-phase flow scaling criteria developed under this program. The nitrogen-water system has been used to isolate the key hydrodynamic phenomena from heat transfer problems. Various tests were carried out to establish the basic mechanism of the flow termination and reestablishment as well as to obtain essential information on scale effects of various parameters such as the loop frictional resistance, thermal center, U-bend curvature, and inlet geometry. It was found that the permanent termination of the natural circulation was related to the head balance between the hot and cold legs. The local flow condition at the inverted U-bend could produce intermittent flow, however was not related to the permanent flow termination. The void distribution in a hot leg, flow regime, and natural circulation rate have been measured in detail for various conditions. Significant effects of the inlet geometry on these were observed. Near the flow termination condition, large amplitude flow oscillations occurred. The occurrence of this type of flow instability is important for safety analyses, because it may lead to loop-to-loop oscillations or flow excursions in a prototype system which has a multi-loop configuration. 相似文献
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对具有长直上升段的自然循环系统,开展了流动不稳定性实验研究。同时,详细分析了低压、高入口过冷度条件下典型的流动不稳定现象。实验表明:自然循环系统的结构、流体的热边界条件会影响自然循环的运行特性及流动不稳定性类型。较高入口过冷度下,高热流密度导致系统脱离稳态后,很难重新回到稳定的两相自然循环流动状态。随着热流密度的提高,系统会经历间歇沸腾、复合动态流动不稳定性等状态。依据实验结果得到了高入口过冷度下的不稳定性边界图。在两相振荡期间,自然循环驱动压头和回路阻力的主要影响因素集中在长直上升段和加热段。加热段出口积聚的大量气泡对上、下游流体的强烈挤压作用是流量大幅振荡及逆流的主要原因。 相似文献