【作者】 王秀礼；

【导师】 袁寿其；

【作者基本信息】 江苏大学 ， 流体机械及工程， 2013， 博士

【摘要】 核主泵是核电站里最关键的核动力设备之一,其功能是在系统充水时赶气,在开堆前循环升温,在正常运行时确保一回路冷却剂循环以冷却堆芯,在事故工况下阻止核事故扩大等。核主泵长期稳定安全可靠的运行对冷却剂输送、堆芯冷却、热量排出及防止核电站事故发生等极为重要。本文主要工作是围绕对各种事故工况下气-汽-液多相混合物的瞬态流动变化规律进行数值模拟,并利用五孔探针、压力脉动探针及振动仪器等对其进行试验研究。主要研究工作和创造性成果有：1.为了确保核主泵在变流量工况下可靠运行,采用数值模拟与试验相结合的方法对核主泵在瞬变工况下,不同叶片数与导叶片数及不同分流叶片进口直径的叶轮动力特性进行研究,结果表明：在变流量过程中,当叶片数为5片、导叶片为11片时,叶轮承受的径向力最小。分流叶片进口直径为0.72D2时,压力脉动在各工况下运行最小。2.针对核主泵在实际运行中会出现流量瞬变问题,先对核主泵在单相变流量过渡过程时内部水动特性进行研究,再分别对流量不变、含气量增加,含气量不变、流量增加及流量与含气量同时变化过渡过程下,对核主泵内部的气液两相瞬变流动规律进行深入的研究,得到了不同瞬变过渡过程中核主泵气液两相流动的瞬态水动力特性。3.为了解决核主泵对惰转过渡过程提出较高的要求,对比了常规惰转、线性惰转及带惰轮惰转等三种模型在停机过渡过程中水动力特性,得出带惰轮的惰转模型在停机惰转过程中的水动力特性最稳定的结论。在此基础上,分别对单相及气液两相混合工况下的停机过渡过程中水动力特性进行了深入的研究,得到了核主泵在停机过渡过程中,叶轮流道内的压力、速度、气体体积分数、涡量、径向力等变化规律。4.针对隐形空化对核主泵叶轮可产生较大危害的特点,阐述了隐形空化过渡过程中汽相的流动变化规律,提出了汽体体积分数随压力的降低呈现指数函数的变化规律。采用小波变换和傅里叶变换对核主泵在不同空化阶段的压力脉动进行了分析,发现在空化初生工况时,核主泵扬程波动频率主要以低频为主,叶轮流道内压力脉动的主频以转频为主,空化所产生的压力脉动对主频影响不明显；在空化发达工况,空化所诱发的压力脉动随空化发展对主频、次主频及脉动幅值的影响越来越大,扬程脉动频率中低频脉动为主；在空化严重工况时,扬程的脉动频率以无规律变化的脉动高频为主,同时包含近乎规律变化的脉动低频。5.首次基于CFD数值模拟与试验相结合的方法对核主泵失水气液两相混合工况下,含气量与空化之间的影响进行了研究,发现含气量对空化影响非常明显,在相同工况下空化区域随着含气量增加而变小。系统分析了气液两相混合工况下含气量对空化断裂工况的影响,发现含气量能延缓空化断裂工况发生。6.首次基于流固耦合技术对核主泵空化与叶轮最大变形量之问的关系进行探索,获得了不同空化阶段对应的叶轮最大变形量的瞬态脉动变化规律及叶轮径向力不平衡变化规律。首次在考虑气液两相的基础上,对流量或含气量的瞬变对核主泵结构静力学及模态分析的影响进行研究。得到了在流量不变时,含气量与核主泵叶轮最大变形量呈现线性变化关系；含气量不变时,叶轮最大变形量随流量增加而增大的结论。7.利用外特性测量设备、五孔探针、压力脉动探针及虚拟仪器对核主泵在各工况下进行系统的静态及瞬态内部流场及外特性测试。通过matlab与orign对试验数据进行处理并与数值模拟数据进行对比可知,试验结果与数值模拟结果总体趋势一致。故通过采用数值模拟与试验相结合的方法可以准确掌握核主泵在各工况下运行的内部流动规律。本研究结果为核电泵及其它气.汽-液多相流动泵的研究提供了理论基础。更多还原

【Abstract】 The reactor coolant pump is one of the most critical nuclear-powered devices in the nuclear power plant. The functions of the reactor coolant pump are to drive the gas out of the system when water-filling, to circulated and heating the nuclear reactors before it starts work, to ensure that the primary coolant circuit work normally to cool the core of the reactor, and to prevent the nuclear accidents expanding under accident conditions. The reactor coolant pump’s long-term stability, safe and reliable operation are of extremely importance to the coolant delivery, cool the reactor core, exhaust the heat and prevent the occurrence of nuclear accidents. The main tasks of this dissertation are to analyze the transient flow variation of gas-liquid two-phase mixture under a variety of accident conditions by numerical simulation, and use the five-hole probe, the pressure pulsation probe and vibration instrument for test validation. Some meaningful research and creative achievements are obtained and listed as follow:1. In order to ensure that the reactor coolant pump can work smoothly during variable flow conditions, adopting the test and numerical simulation during the transient operating conditions to study the dynamic characteristics of the complex impeller, which has different number of blades and guide vanes and different splitter inlet. The result shows that during the process of variable flow, when the blade number is five and the guide vane number is eleven, the radial force upon the impeller is the smallest. The pressure pulsation is the minimum under a variety of conditions, as the splitter blade inlet diameter is0.72D2.2. In the actual operation, for reactor coolant pump will encounter the flow transient problems, so the internal hydrodynamic characteristics in single-phase variable flow transition process was analysed firstly. Then the author conducted in-depth research of the gas-liquid two-phase transient flow law inside the reactor coolant pump, in the transition process of unchanged in flow rate and increase in gas content, gas content unchanged and flow increases, or the flow and gas content change together. The reactor coolant pump gas-liquid two-phase transient hydrodynamic flow characteristics under the different transient transition process are obtained.3. The hydrodynamic characteristics of three inertial rotation models was compared during the downtime transition process. It turn out that the hydrodynamic characteristics of the inertial rotation model with idler is the most stable one during the downtime idle process. Based on this, it continues to study deeply on the hydrodynamic characteristics of the single-phase and gas-liquid two-phase mixed conditions in the downtime transition process. From the study, the variation laws of tract pressure, speed, gas volume fraction, vorticity and radial force within the reactor coolant pump impeller are obtained during the downtime transition process.4. Considering the feature of invisible cavitation, which does greater harm to the reactor coolant pump impeller, the bubble phase flow variation law in the invisible cavitation transition process was elaborated, and found out that the exponential function variation law of the gas volume fraction with the pressure decreasing. The wavelet transform and Fourier transform methods are adopted to analyze the reactor coolant pump pressure pulsation in different stages of cavitation, and the characteristics of pressure pulsation in different cavitation stages was obtained. In the incipient cavitation conditions, the low frequency was predominantly factor in the fluctuation frequency of head of the reactor coolant pump,and the rotation frequency was predominantly factor in the main frequency of pressure fluctuation in impeller passages. The pressure fluctuation induced by the cavitation had little effects on the main frequency.In the developed cavitation condition,the pressure fluctuation induced by cavatation has come to matter much more to the dominant frequency, sub-main frequency and oscillation amplitude.The low and medium frequency were predominantly factors in the fluctuation frequency of head.In serious condition of cavitation,the pressure pulsations are composed of irregular high-frequency and regular the low and medium pressure pulsations.5. The relationship between the gas content and the cavitation was researched by CFD numerical simulation and experiment under the dehydration gas-liquid two-phase mixed conditions. The results showed that gas content on cavitation was very obvious impact. With the increase of gas content, cavitation area became smaller under the same conditions. The gas content impact on the cavitation fracture conditions was systematically analyzed under the conditions of gas-liquid two-phase. The result showed that gas content could delay the cavitation fracture conditions.6. Based on the fluid-structure coupling techniques to systematically study the relationship between the reactor coolant pump cavitation and the impellermaximum deformation, the variation laws of the impeller maximum deformation transient pulsation corresponding different cavitation stages and the impeller radial force imbalance variation law are obtained. The reactor coolant pump, with dynamical modal analysis and structural statics, was researched on the basis of considering the gas-liquid two-phase conditions. It was found that when the flow rate was unchanged, the gas content and the reactor coolant pump impeller maximum amount of deformation presented a linear variation, and when the gas content was unchanged with the flow rate increasing, the impeller maximum amount of deformation increased7. The comprehensive and systematic tests of static and transient internal flow field and the hydramic characteristics were conducted with the five-hole probe, the pressure pulsation probe, vibration instrument and the virtual instrument. It was also proved that the measured results were in accord with the calculated ones. The research results provide some reference for the reactor coolant pump or other gas-vapor-liquid multiphase pumps.更多还原