直边入口直通道临界流的理论研究

在Ｈｅｎｒｙ模型的基础上，作了一系列改进并对摩擦进行了修正，得到一均匀非平衡模型。该模型比Ｈｅｎｒｙ模型计算范围广，可计算初始饱和、欠热液体及进口含汽量不为零的直边入口、直通道、Ｌ／Ｄ〉１２的临界流。     

ADS无窗靶件流场结构和自由界面数值模拟研究

自由界面流动现象是加速器驱动次临界系统(ADS)无窗靶件研究的重要组成部分。采用计算流体动力学(CFD)方法,对上海交通大学设计的无窗靶件流道结构中的自由界面流动水力学行为进行数值模拟研究。数值模拟使用FlUENT软件平台,采用体积流体法(VOF)与界面追踪方法结合湍流大涡模型(LES),进行Re在35000⁸0000工况下的非稳态计算。模拟结果得到了自由界面稳定性、自由界面宽度、大尺度漩涡结构、漩涡滞止区长度和锥形段流道沿程压力随Re变化的规律。     

MCNP程序中平行面源直穿贡献算法的改进

点通量估计方法广泛应用于探测区域远小于系统的模型。对于平行面源,MCNP5计算源粒子的直穿贡献部分的代码有错误,导致点通量计算结果与体通量计算结果差异较大。此外,MCNP程序（包括MCNP5和MCNP4C）对平行面源的直穿贡献进行多次重复计算,浪费计算资源,本文通过对算法进行改进,使计算时间大幅缩短。     

一种新型光栏直场加速管

文章通过对静电加速器加速管的场形计算和粒子轨迹计算，提出了有效地抑制次级电子的“Ｕ”型光栏直场加速管，经过加速器中高压试验和γ射线能谱测量，证实了“Ｕ”光栏直场加速管所预期的性能。     

密度锁内无扰动时稳态温度场分析

实验模拟了密度锁内无扰动时稳态温度场分布。结果发现,稳态温度分布曲线上存在一个温度分层结束点;它是导热层与恒温层的分界,只有当温度分层结束点在密度锁内才能有效地抑制传热。应用半无限大平板导热模型、一维等截面直肋稳态导热模型和Fluent流体计算软件对无扰动时稳态温度场分布进行了理论计算。结果表明,半无限大平板导热模型是计算密度锁内无扰动时稳态温度场分布和温度分层结束点位置的最佳方法。     

两相临界流的两流体不平衡模型研究

研究的两流体不平衡模型，用来计算初始滞止状态为饱和或过冷流体通过通道的临界流量，模型中既考虑了两相之间的动力学不平衡，也考虑了相间热力学不平衡──温度差异。引入汽泡运动弛豫时间方程，结合两相质量守恒方程，动量守恒方程组成五方程模型。通过解汽泡在无限大介质中边界层非稳态导热问题，获得界面热负荷，井利用两相混合物能量方程，获得液相过热度，从而计算出蒸发速率。引用合适的经验关系式，计算界面摩擦切应力，壁面摩擦切应力。提出厂圆弧入口和直段入口两类边界条件的处理方法，设置异质汽核密度为可调参数，当其值取为２．５×ｌ０１１时，在较阔的压力范围内，对不同的长径比Ｌ／Ｄ，预测结果和实验值符合较好。     

基于CSG的堆芯蒙特卡罗输运模型可视化转换技术研究

为了提高堆芯蒙特卡罗精细输运计算模型（简称MC计算模型）的三维可视化分析效率，在充分调研目前MC计算模型三维可视化工具发展现状的基础上，通过对不同类型几何模型的特点，以及构造实体几何（CSG）模型的描述方法进行分析，提出了一种堆芯精细MC计算模型的自动三维可视化转换方法，并对可视化转换过程涉及到的CSG模型到边界描述（BREP）模型转换、BREP模型网格离散和CSG模型转换效率优化等关键技术进行了深入研究。测试结果表明，提出的MC计算模型自动三维可视化方法在功能和效率方面均能满足工程使用需求。      

基于汽泡壅塞流模型的竖直圆管临界热流密度理论研究

为研究单管壅塞流的临界热流密度（CHF）现象，建立了基于近壁处汽泡壅塞机理的CHF计算模型。模型通过求解相应的质量、动量和能量方程，再结合汽泡直径脱离模型、壁面临界空泡份额等模型，从而计算得到CHF。将模型计算结果同实验值比较，吻合良好，验证了模型的正确性。在此基础上，以建立的CHF模型为基础，研究了进口焓差、质量流速、管径和加热长度对CHF的影响，为预测壅塞流CHF提供依据。      

蒙特卡罗方法在Soller中子狭缝准直器优化设计中的应用

Soller型中子狭缝准直器是中子散射谱仪部件之一，用来对中子束流进行准直。准直器的设计不仅需要对吸收材料进行选择，吸收材料的厚度选择也很重要。准直器的透射率和空间的限制对准直器的长度提出要求。应用以蒙特卡罗方法为基础的模拟计算对准直器进行优化设计是一种新的尝试。采用MCNP程序对准直器的长度和吸收片厚度进行了模拟优化设计，并对计算结果进行了评定。     

基于多级混合澄清槽的PUREX流程的计算模型

主要通过建立分配比模型、化学反应模型、传质模型构建了一套基于混合澄清槽的PUREX流程中关键循环过程的计算模型（mathematical model for main PUREX process based on mixer-settler，简称MPMS），用于计算各级单元的物料浓度。通过检验两组具有代表性的PUREX工艺流程，模拟结果较好地匹配实验数据，表明该计算模型具有良好的精确性。该计算模型将为基于多级混合澄清槽的PUREX流程模拟提供有益帮助。     

A study of the effects of the location of flashing inception on maximum and minimum critical two-phase flow rates:: Part II: analysis and modelling

A general unified model is developed to predict one-component critical two-phase pipe flow. An extension of the Henry [Henry, R.E., 1970. The Two-Phase Critical Discharge of Initially Saturated or Subcooled Liquid. Nucl. Sci. Eng. 41, 336-342.] and Henry and Fauske [Henry, R.E., Fauske, H.K., 1970. The two-Phase critical Flow of One-Component Mixtures in Nozzles; Orifices and Short Tubes, ASME J. Heat Transfer, May 1970.] models to incorporate the effects of wall friction and the location of flashing inception is proposed. Modelling of the two-phase flow is accomplished by describing the evolution of the flow between the location of flashing inception and the exit (critical) plane. The model approximates the nonequilibrium phase change process via thermodynamic equilibrium paths. Included are the relative effects of varying the location of flashing inception, pipe geometry, fluid properties and length to diameter ratio. The model predicts that a range of critical mass fluxes exist and is bound by a maximum and minimum value for a given thermodynamic state. This range is more pronounced at lower subcooled stagnation states and can be attributed to the variation in the location of flashing inception. The model is based on the experimental study of critical two-phase flow rates of saturated and subcooled water through long tubes given in Part I of this work. In that study, the location of flashing inception was accurately controlled and adjusted through the use of a new device. The data obtained revealed that for fixed stagnation conditions, the maximum critical mass fluxes occurred with flashing inception located near the pipe exit; while minimum critical mass fluxes occurred with the flashing front located further upstream. The results of the present study, as well as available data since 1970 are compared with the model predictions. These data cover a wide range of conditions and include test section L/D ratios from 25 to 302 and a temperature and pressure range of 110-280°C and 0.16-6.9 Mpa, respectively. The predicted maximum and minimum critical mass fluxes show an excellent agreement with the range observed in the experimental data.     

RELAP5／MOD2和CATHARE两相临界流模型的评价

分析和评价了2个程序中的两相临界流模型。指出RELAP5/MOD2在上游低欠热度或低含汽率条件下计算的临界流量偏低并不能反映几何尺寸(L/D)对临界流量的影响。CATHATE临界流模型较完善,它计算的临界流量与实验符合得很好。建议用非均匀热不平衡声速来修改RELAP5/MOD2的两相临界流判据,或者补充短喷管和孔板的临界流量实验关系式或实验数据,以改正RE-LAP5/MOD2的上述2个缺点。     

Method of Critical Power Prediction Based on Film Flow Model Coupled with Subchannel Analysis

A new method was developed to predict critical powers for a wide variety of BWR fuel bundle designs. This method couples subchannel analysis with a liquid film flow model, instead of taking the conventional way which couples subchannel analysis with critical heat flux correlations. Flow and quality distributions in a bundle are estimated by the subchannel analysis. Using these distributions, film flow rates along fuel rods are then calculated with the film flow model. Dryout is assumed to occur where one of the film flows disappears. This method is expected to give much better adaptability to variations in geometry, heat flux, flow rate and quality distributions than the conventional methods.

In order to verify the method, critical power data under BWR conditions were analyzed. Measured and calculated critical powers agreed to within ±7%. Furthermore critical power data for a tight-latticed bundle obtained by LeTourneau et al. were compared with critical powers calculated by the present method and two conventional methods, CISE correlation and subchannel analysis coupled with the CISE correlation. It was confirmed that the present method can predict critical powers more accurately than the conventional methods.     

LBB泄漏率计算与热力学非平衡效应影响评估

裂纹泄漏率计算是破前漏（LBB）在核电站管道和设备上应用的基础。在Fauske模型基础上,整个裂纹内流体流动假设为等焓过程且充分考虑摩擦效应对裂纹临界泄漏率的影响,利用Mathcad计算得到了管道裂纹两相泄漏率,与已有文献中实验数据进行对比,将其发展成为可准确计算裂纹泄漏率的计算机程序。同时根据两相流动不平衡理论,对模型进行热力学不平衡参数影响修正。结果表明：随裂纹长径比(L/D)增大,两相泄漏率减小;随裂纹入口滞止压力增大,两相泄漏率增大;裂纹入口流体过冷度增大,两相泄漏率增大,数学模型计算结果与实验结果趋势一致,但忽略热力学非平衡效应,数学模型计算得到的临界流量小于实验流量。对于热力学不平衡参数修正后模型,模型计算得到的结果均与实验数据符合很好,故由修正后模型编制的Mathcad程序可完成裂纹泄漏率的准确计算,为LBB在核电站管道上的应用提供基础。     

基于液膜蒸干模型的低压低流量环状流CHF理论研究

为对低压低流量下的环状流临界热流密度（CHF）进行预测，建立了考虑液膜蒸发、液滴沉积和夹带的液膜蒸干模型，并用已有的实验数据对其进行验证。计算结果表明：在实验参数范围内，CHF计算值与实验值相对偏差在25%以内，两者符合较好。以建立的环状流CHF模型为基础，研究了进口焓差、质量流速、管径和加热长度对CHF的影响。该模型能够有效地计算低压低流量环状流CHF和分析CHF随不同参数的变化趋势。     

非稳态流体力作用下两相流管束流弹失稳研究

流弹失稳会引起传热管振幅过大而发生磨损破坏，是两相流作用下蒸汽发生器管束流致振动的重要机理。为了较为准确地预测两相流作用下圆柱管的失稳临界流速，对试验测量的两相流非稳态流体力进行参数拟合，建立了气-水两相流作用下单管的动力学模型。通过无量纲化，运用Galerkin方法对方程变量进行离散后，联立求解方程得到了不同空泡份额的临界流速。数值结果表明，数值解与试验测得失稳临界流速较为吻合，验证了该模型可用于两相流传热管临界流速的预测。      

Simulation of SBLOCA based on an Improved Choked Flow Model for RELAP5/MOD3 Code

This paper is a continuation of the present author’s previous publication dealing with a new choked flow model for two-phase flow. The model based on a hyperbolic one-dimensional two-fluid model, where in the momentum equations the terms representing the interfacial pressure difference has been included in lieu of the virtual mass force terms. The new choked flow model is an improvement upon the choked flow model of the current RELAP5/MOD3 code, which itself is based on the Trapp–Ransom method. The author compares the predictions of this improved model with Trapp–Ransom model and Henry–Fauske model, for an assumed flow in a vertical pipe. The author simulates a typical PWR system with a hypothetical SBLOCA as well, and compares the system behaviors predicted by RELAP5/MOD3, based on the aforementioned choked flow models. He shows that the improved choked flow model leads to better predictions.     

新概念熔盐堆物理计算方法研究及程序设计

考虑新概念熔盐堆燃料盐的流动特性,从基本的粒子守恒方程出发,推导了熔盐堆的中子动力学模型,并采用数值方法对3种工况下熔盐堆的临界问题进行计算,考察流动对有效增殖系数、快中子分布、热中子分布及缓发中子先驱核分布的影响。结果表明：质量流量对有效增殖系数的影响很小,对热中子分布的影响比对快中子分布的影响大,而质量流量越大,缓发中子先驱核移出堆芯的比率也越大。     

基于竖直圆管空气-水两相流实验的相间曳力模型研究

研究两相流相间阻力特性对系统程序关键本构模型封闭具有重要意义。本文基于竖直圆管开展了空气-水两相流实验,采用四探头电导探针对空泡份额、气泡弦长和界面面积浓度等气泡参数的径向分布进行了测量。结果表明空泡份额和气泡弦长呈现“核峰型”分布,而界面面积浓度并没有表现出随流速的单调关系。进一步开发了泡状流和弹状流的相间曳力模型,考虑了液相表观流速与管径对气泡尺寸分布的影响,建立了临界韦伯数与不同液相流速的关系。计算得到的空泡份额和界面面积浓度与实验数据整体符合较好,验证了模型的可靠性,为两相流相间阻力特性研究提供参考意义。     

Analytical Study of Thermo-Hydrodynamic Behavior of Reflood-Phase during LOCA

The objective of this study is the establishment of the thermo-hydrodynamic model of the reactor core during reflood phase of LOCA.

Based on the quench model proposed by the author, and assuming a reflood model including a flow model and a set of the thermo-hydrodynamic correlations, a reflood analysis code named “REFLA-1D” was developed.

Considerably close agreement between PWR-FLECHT tests and the results calculated by REFLA-1D code for the critical Weber number We_c= 1 was obtained for fuel clad temperature histories and the quench time and the quench temperature except for the quenching from the top of the fuel rod. It was found that the errors of calculated quench time and temperature are within ±20% under the following conditions: (1) pressure 4.5–1.5 kg/cm²·a or core inlet velocity 15–4.8 cm/s, (2) inlet subcooling more than 30°C. In the transition flow region, the calculated tendency of the temperature histories is different from the measured. This reflood model appears to be reasonable but some modifications on the low flooding quench model and the transition flow are necessary.