波纹管对气体离心机流场影响的数值研究

波纹管是超临界气体离心机的核心部件,可改变转子流场的空间结构.为了研究波纹管对气体离心机流场的影响,在单向关联水力学模型和Iguassu离心机模型基础上,在交错网格上离散二维N-S方程组,并使用同伦算法和牛顿迭代法求解,对包含内、外波纹管的流场分别进行数值模拟.结果表明,外波纹管对环流几乎没有影响,但在不改变贫取料压强...     

冷却剂与含格架燃料棒束多场耦合分析

燃料棒束作为压水堆燃料组件的组成部分,其热工和结构特性直接关系到反应堆的安全。本文利用ANSYS WORKBENCH软件分析了冷却剂在5×5含定位格架燃料棒束通道内流动的分布,采用冷却剂与燃料棒束多场耦合的方式研究了燃料棒束的流动传热特性和结构形变特性。结果表明：定位格架扰动冷却剂形成横向二次流并在下游棒束间形成绕流;多场耦合条件下二次流峰值速度和平均速度均小于单流场的;二次流与燃料棒的热应力使棒束发生形变,功率和流动分布的不均匀导致形变在轴向和径向的不均匀;相较于无格架情况,定位格架的存在使冷却剂的搅混流动更加明显,冷却剂对燃料棒冲击增大;在有、无定位格架两种情况下棒束形变均很小,可保持原本结构的稳定。     

基于双区域模型的钠冷快堆组件子通道分析程序的开发与验证

子通道分析程序是钠冷快堆堆芯热工水力设计和安全分析的重要工具。本文为计算和分析钠冷快堆组件在径向均匀与倾斜功率分布工况下的热工水力特性,利用双区域绕丝交混模型开发了一款适用于钠冷快堆组件分析的子通道程序SPLICA,并与FFM2A 19棒束实验数据与WARD 61棒束实验数据进行了对比验证。由于本文开发的子通道分析程序SPLICA使用了详细的绕丝交混模型,与经过二次开发后的COBRA程序的计算结果相比,对于FFM2A实验SPLICA程序计算得到的结果与实验结果符合得更好。这两个实验数据的验证结果证明了本文开发的子通道分析程序的准确性以及对高流量工况和低流量工况均具有良好的适用性。本程序能为钠冷快堆组件热工水力分析提供有效的设计和研究手段。     

Experimental and numerical simulation of air-water two-phase flow in the rod bundle with grid spacer

1 Introduction Grid spacer is the key part of reactor fuel assem-bly. The presence of spacers in fuel assemblies affectsvarious thermal-hydraulic characteristics of the reactorcore. The grid spacer with fine performance can im-prove thermal-hydraulic performance of the core fuelassembly and enhance the critical heat flux withouttoo much augment of the pressure loss. As a result,the implementation of grid spacer with high thermalperformance provides more thermal margin, then in-creases s…     

垂直向上流动通道内环状流干涸点的理论研究

本文基于分离流模型,建立了垂直向上流动环形通道内环状流的三流体模型,并对干涸点进行了数值模拟.比较计算结果和实验结果,发现两者符合较好.结果显示:当干涸点发生在内管并且外管热流密度不变时,临界含汽率随曲率和间隙的减小而增大,当干涸点发生在外管且内管热流密度不变时,情况相反;对于固定的间隙,当外管内径大于20 mm时,或间隙小于0.5 mm时,压力和质量流速对临界含汽率的影响非常微弱.     

Improvement of the spreading effect of atmospheric pressure microplasma jet treatment through shielding-gas-controlled focusing

The spreading effect of atmospheric pressure microplasma jets (APμPJ) on the surface of materials will increase the etching area, and controlling the diameter of the jet can improve the precision of surface treatment. In this work, a two-dimensional axisymmetric simulation model is established to analyze the effect of nitrogen (N2) shielding gas on helium (He) from gas dynamics. In addition, by etching the polyethylene terephthalate film, the relationship between the etching effect and aerodynamic analysis is verified. The simulation results are similar to the experimental results, indicating that N2 shielding gas has a focusing effect which is related to the N2 flow rate, distance difference between the inner and outer tubes, and outer tube nozzle diameter. It is hoped that the results of this work can provide a certain reference for the use of shielding gas to control the jet flow of APμPJ.     

Numerical investigations of thermal mixing performance of a hot gas mixing structure in high-temperature gas-cooled reactor

A numerical simulation study was performed to clarify the thermal mixing characteristics of coolant in the core bottom structure of the high-temperature gas-cooled reactor(HTR). The flow field and temperature field in the hot gas chamber and the hot gas duct of the HTR were obtained based on the commercial computational fluid dynamics(CFD) program. The numerical simulation results showed that the helium flow with different temperatures in the hot gas mixing chamber and the hot gas duct mixed intensively, and the mixing rate of the temperature in the outlet of the hot gas duct reached 98 %. The results indicated many large-scale swirling flow structures and strong turbulence in the hot gas mixing chamber and the entrance of the hot gas duct, which were responsible for the excellent thermal mixing of the hot gas chamber and the hot gas duct. The calculated results showed that the temperature mixing rate of the hot gas chamber decreased only marginally with increasing Reynolds number.     

进出口阻力对倒U型管束内倒流特性的影响分析

蒸汽发生器（SG）倒U型管束内倒流问题增大了自然循环条件下SG的流动阻力，降低了系统自然循环能力，对反应堆安全产生了负面影响。针对上述问题，以船用SG为研究对象，分别采用理论分析和计算流体动力学（CFD）数值模拟方法，通过修圆并联倒U型管束内管板开孔，研究了采用改进方案前后管板的流量分配和倒流特性。结果表明，通过修圆短管管板开孔，在自然循环工况下能有效降低SG流动阻力，增大短管的流量分配，从而降低倒流临界流量，延缓倒流现象的发生。研究结论为SG倒U型管束内倒流问题提供了一种可行的解决方案，可以为解决倒流问题研究提供支持。      

高温气冷实验堆堆芯出口热气联箱混合性能对比试验

１０ＭＷ高温气冷实验堆堆芯出口冷却剂温度径向分布很不均匀，若不使之均匀化，将造成蒸汽发生器件部上过大的热应力，设置在堆底反射层中的堆芯出口热气联箱的作用之一是使冷却剂氦气在其中得到充分的热混合。     

钠冷快堆非能动停堆机构动导管共轭换热数值分析

为解决钠冷快堆非能动停堆机构动导管和其内外两侧的液态钠构成的共轭换热问题，采用Trelis前处理软件生成全域高质量六面体网格，基于开源CFD软件OpenFOAM中的chtMultiRegionSimpleFoam求解器，得到对动导管数值分析的温度分布结果。计算结果表明，动导管内壁面周向0.07 m范围内温差为97 ℃，动导管轴向0.17 m高度范围内的温差为80 ℃。在这样窄的范围内该温差将会产生较大的热应力，数值分析结果将为动导管力学设计提供重要的输入条件。     

三环路压水堆压力容器上腔室交混矩阵数值研究

使用STAR-CCM+软件对三环路压水堆压力容器上腔室流场进行了大规模、精细化三维数值模拟,并采用组分跟踪方法分别对157个燃料组件出口冷却剂流动进行计算,构造了一个具有3×157个元素的“上腔室交混矩阵”,用该矩阵即可定量、精确地描述冷却剂从堆芯流出后,经上腔室内交混并再分配到各热管道的复杂流动过程。研究发现堆芯流出的冷却剂在压力容器上腔室内的交混是并不充分的,径向上不同位置燃料组件流出的冷却剂会在上腔室同热管道的接口区域存在明显的对应关系,而燃料组件径向功率分布的差异必然导致热管道中冷却剂热分层现象的产生。      

Thermal performance test of the hot gas ducts of HENDEL

A hot gas duct provided with internal thermal insulation is to be used for high-temperature gas-cooled reactors (HTGR). This type of hot gas duct has not been used so far in industrial facilities, and only a couple of tests on such a large-scale model of a hot gas duct have been conducted. The present report deals with the results of the thermal performance of the single tube type hot gas ducts which are installed as parts of a helium engineering demonstration loop (HENDEL).Uniform temperature and heat flux distribution at the surface of the duct were observed, the experimental correlations being obtained for the effective thermal conductivity of the internal thermal insulation layer. The measured temperature distribution of the pressure tube was in good agreement with the calculation by a TRUMP heat transfer computer code. The temperature distribution of the inner tube of the co-axial hot gas duct was evaluated and no hot spot was detected.These results would be very valuable for the design and development of HTGR.     

Preliminary Design and Optimization of the Multilayer Alloy Divertor Target Box

The target box is designed to protect the body of divertor cassette. Every new EAST divertor cassette has two target boxes covering its body. The paper is about the structure design and optimizing scheme of the outer/inner tokamak divertor target box. The preliminary structure of target box is built up firstly. And the distribution of thermal load on the target boxes is discussed based on the theory and experiment results of plasma. Then some parameters of the target box’s structure, such as cooling tube radius, cooling water flow velocity and the length between two cooling tube, are selected to discuss the range of values’ limits. Based on the above results, a series of thermal simulations are made through changing the structure parameter values. Finally, using these simulation results the optimal design parameters set are found out.     

铅铋快堆螺旋管直流蒸汽发生器热工水力特性数值研究

本研究以铅铋快堆螺旋管直流蒸汽发生器（HOTSG）设计结构为研究对象,采用精细网格与多孔介质相结合的物理建模方法,通过一次侧三维湍流计算与二次侧用户自定义函数（UDF）分区传热计算相耦合的手段,在FLUENT求解器中开展了蒸汽发生器的热工水力特性数值分析研究。研究表明:铅铋入口附近的流量分配孔和腔室对应的直管段区域出现铅铋流速峰值,径向最大速度为0.431 m/s;入口腔室至管束区位置受到阻力突变的影响,压力、横流速度、轴向速度变化较大;热工参数变化符合流动与传热机理,临界热流密度（CHF）点附近一二次侧温差最大为109.61 K,此处最大热流密度为323.55 kW/m2。该研究将为铅铋快堆HOTSG结构设计、流致振动及安全评价提供重要的参考。      

Structure of air–water two-phase flow in helically coiled tubes

Air–water two-phase flow in helically coiled tubes is investigated experimentally to elucidate the effects of centrifugal acceleration on the flow regime map and the spatial and the temporal flow structure distribution. Three kinds of test tubes with 20 mm inner diameters including a straight tube are used to compare the turbulent flow structure. Superficial velocities up to 6 m/s are tested so that the centrifugal Froude number covers a range from 0 to 3. The interfacial structure is photographed from two directions by a high-speed video system with synchronized measurement of local pressure fluctuations. The results reveal that the flow transition line alters due to centrifugal force acting on the liquid phase in the tube. In particular, the bubbly flow regime is narrowed significantly. The pressure fluctuation amplitude gets large relatively to the average pressure loss as void fraction increases. The frequency spectra of the pressure fluctuation have plural peaks in the case of strong curvature, implying that the periodicity of slugging two-phase flow is collapsed by an internal secondary flow activated inside the liquid phase. Moreover, under large Froude number conditions, the substantial velocity of the gas phase that biases to the inner side of the helical coil is slower than the total superficial velocity because the liquid flow is allowed to pass through the outer side and so resembles a radial stratified flow.     

竖直圆管内泡状流界面参数分布特性

采用双头光纤探针对内径为50 mm竖直圆管内空气-水两相泡状流界面参数径向分布特性进行了实验研究。气液两相表观速度变化范围分别为0.004～0.05 m/s和0.071～0.283 m/s。结果表明,竖直管内向上泡状流局部界面面积浓度（IAC）、空泡份额及气泡频率径向分布相类似,即气相流速较低时管道中间很大范围内以上3个局部界面参数几乎恒定,近壁区迅速下降到较低值;随气相流速的增加,局部界面参数在管道中心出现峰值。本实验中气泡聚合与破碎现象较少发生,索特平均直径沿径向近似均匀分布,且随气液两相流速变化很小。通过气泡横向受力解释了局部界面参数分布的影响机理。     

Axial static pressure variations in inner and side subchannels of a 61-tube wire-wrap bundle

Measurements of axial distribution of the static pressure in an inner and side subchannel of a 61 wire-wrap tube bundle obtained with water at atmospheric conditions are presented. The wire wrap configuration is different from those used by previous workers and more representative of a bundle for the blanket of a Gas Cooled Fast Reactor. The data display axial static pressure variations which are attributed to the interchannel cross flow induced by the wire-wrap configuration. The static pressure drop over one wire pitch agrees well with the bundle pressure drop based on a bundle average Reynolds number and a friction factor f = 0.436 Re^−0.263 (Re > 2000). The experimental data obtained with water provide a useful benchmark to model and check the accuracy of thermal-hydraulic codes used for the analysis of subchannel flow distribution and pressure drop in wire wrap tube bundle cooled with one-phase fluid.The nodal subchannel code COBRA-IV was modeled by adjusting the forced cross-flow function to match the measured axial static pressure distribution in an inner and side subchannel. Some discrepancy remained in the static pressure profile in the side channel attributed to the flow distortion at the bundle exit.     

基于CFD方法的铅铋冷却燃料棒束的热工水力特性分析

铅铋冷却快堆作为第4代反应堆候选之一具有安全性高等特点,研究其在正常工况下的热工水力特性具有重要意义。本文基于商用计算流体力学（CFD）软件STAR-CCM+,使用流固耦合的方法对带有绕丝结构的19棒束铅铋组件进行数值分析,探究了质量流量、功率等边界条件对组件内部流动传热特性的影响。模拟计算结果表明：CFD方法在子通道中心温度和壁面温度预测上与实验结果取得了较好的一致。同时,绕丝结构的存在使得子通道之间存在周期性的横向交混,并使得棒束表面温度呈现震荡。随质量流量的增加,子通道间横向交混增大。功率变化对通道间的横向交混速度的影响较小,冷却剂温度的横向分布无明显差异。     

带MVG和MSMG的5×5全长棒束单相流场和温度行为数值分析

定位格架作为燃料组件的关键部件之一,直接影响到燃料组件的热工性能。本文对带结构格架（MVG）和跨间搅混格架（MSMG）的5×5全长加热棒束单相流场和温度场采用计算流体力学（CFD）程序进行数值分析研究,获得该特征棒束组件出口二次流场以及温度场分布特性。研究表明,定位格架下游流场受定位格架和距离的影响,定位格架上游流场对下游二次流几乎无影响,定位格架导致流体强烈的横向二次流,增强了流体和加热棒之间的换热能力,使得棒束子通道截面流体温度更加均匀。与5×5全长棒束出口子通道温度的实验数据对比分析表明,获得的计算模型可以较好地分析该型棒束组件结构温度场行为。      

The effect of a CANDU fuel bundle geometry variation on thermalhydraulic performance

The effect of fuel bundle geometry has been evaluated using the subchannel code ASSERT to enhance the thermalhydraulic performance. Based on the configuration of a standard 37-element fuel bundle, the element diameter in each ring has been changed while those of other rings are kept as the original size. The dryout power of each element in a fuel bundle has been obtained for the modified fuel bundle and compared with that of a standard fuel bundle. The results obtained show that the modification of element diameter largely affects the thermal characteristics of the subchannel on the upper region of a modified element due to the buoyancy drift effect. The explicit effect of the element size on the dryout power of a fuel bundle is investigated by acquiring comprehensive numerical solutions. It is found that the dryout power of a fuel bundle has a tendency to increase as the element size decreases, except for the case where the outer ring is modified. The dependency of the transverse interchange model on the present results has been assessed by examining the dryout power of a bundle for different mixing coefficients and buoyancy drift models.