共查询到18条相似文献,搜索用时 921 毫秒
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采用高雷诺数(Re)k-ε模型与壁面函数法对液态金属钠在环管中湍流流动传热特性进行计算,并与实验结果进行比较,结果表明计算值与实验结果符合较好。应用该方法研究湍流程度、加热条件、几何条件等因素对液态金属钠在环管中湍流传热特性的影响。研究表明,湍流程度对传热的影响主要集中在流道前半段,后半段分子扩散对传热的影响逐渐凸现出来,使不同湍流程度下传热特性的区别逐渐缩小;初始温度与加热热流密度对传热特性无明显影响;环管间隙增大,湍流传热效果增强,同等间隙时管径变化对传热特性无明显影响。 相似文献
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对液态金属钠在环形通道内的单相流动换热特性进行了实验研究。结合实验数据,将液态金属钠单相流动分为层流区(Re≤2 000)、过渡区(2 000Re≤4 000)及湍流区(Re4 000),分别拟合得到不同流态下摩擦系数的计算关系式,并拟合得到液态金属钠环形通道内换热特性的相应关系式。结果表明:液态金属钠单相流动特性与常规流体(如水)类似,其层流区摩擦系数略大于水,湍流区与水的很接近。液态金属钠对流换热过程中,导热项占较大份额,同时Nu随Pe的增大而略有增大。 相似文献
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工程上常采用RANS湍流模型进行热工水力相关的数值模拟,然而液态铅铋合金(LBE)具有独特的热物性,常规湍流普朗特数模型和RANS湍流模型对其流动与传热模拟的适用性有待研究。为更准确地描述绕丝燃料组件内LBE的流动与换热过程,本文基于大涡模拟对湍流普朗特数模型和RANS湍流模型进行优选。首先,采用四种湍流普朗特数模型对绕丝燃料组件内LBE的流动与传热过程进行大涡模拟,对比分析实验数据和模拟结果并进行模型优选。基于优选的湍流普朗特数模型,评价RANS湍流模型对LBE数值模拟的适用性和准确性。结果表明,Cheng湍流普朗特数模型和SST k-ω模型对LBE流动与传热模拟的准确性和适用性最高。 相似文献
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为准确预测低普朗特数流体在燃料组件棒束子通道内的传热特性,需选取合适的湍流普朗特数模型。针对5种不同的湍流普朗特数模型,基于三角形棒束换热关联式,研究采用剪切应力传输(Shear Stress Transfer,SST)k-ω湍流模型,分析不同的棒束子通道结构,并与液态铅铋实验验证的换热关联式计算结果进行对比,分析不同棒径与节径比条件下各种湍流普朗特数模型的适用性。分析研究结果表明,整体湍流普朗特数模型不仅与雷诺数Re、贝克莱数Pe有关,还与节径比P/D有关;在节径比1.3~1.7范围内Kays学者提出的局部湍流普朗特数模型模拟结果与Mikityuk关系式计算值较为吻合;各种湍流普朗特数模型均有最佳的节径比适用范围。因此,相关模型能够用于不同节径比条件下三角形棒束子通道内铅铋传热特性的预测。 相似文献
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Approximate measurements were made on fuel fragmentation of stainless steel/sodium and copper/sodium systems: the surface area of stainless steel increased by a factor of 260 to 3.1 and that of copper by a factor of 300 to 2.7 m2/kg. The number of particles obtained was about 108 per kg fuel. The conditions were: stainless steel 1600°C, copper 1927°C, sodium 400°C at 1 bar ambient pressure (argon cover gas); no detectable pressures accompanied the interaction.A violent sodium boiling model is used for the explanation of the results. A specified number of sodium vapor bubbles grow and collapse with high frequency on the contact surface. The collapse effectively increases the fuel (=heating) surface, and an appropriate energy transfer coefficient is assumed. Contact temperatures, nucleation, bubble statistics, mechanical energy transfer, surface increase and heat transfer are coherently treated and describe the fragmentation transient. The copper surface area is calculated to increase by a factor of about 750 to 6.6 m2/kg within very short times of 1 ms or even less, the stainless steel surface by 200 to 2.4 m2/kg. 相似文献
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I. I. Novikov A. N. Solovyev E. M. Khabakhpasheva V. A. Gruzdev A. I. Pridantsev M. Ya. Vasenina 《Atomic Energy》1956,1(4):545-560
An investigation was undertaken of heat transfer to molten sodium during turbulent flow in a round copper or nickel tube. An interpolation formula was obtained. Experiments were conducted to determine thermal resistance between liquid sodium and a solid wall of copper, nickel, and stainless steel. Methods were developed for measurement of viscosity, temperature conductivity and density of molten metals. Results are given for measurements of these physical parameters for molten alkali metals (sodium, potassium, lithium and the eutectic solution of sodium and potassium) in a broad interval of temperatures. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(10):618-619
An experimental study was performed on the heat transfer to a turbulent water film which is falling down the outside surface of a heated vertical tube. The test section was made of stainless steel tube 13 mm in outside diameter and 1,500 mm long. It was found that a nearly constant heat transfer coefficient was obtained for the lower half of the test section covering a length of about 1 m, which was direct-heated by electric current. The resulting values of the Nusselt number in this region were correlated to the Reynolds number, and the plots fell in a region intermediate between those given by Wilke and by McAdams. An analytical model taking account of the undulation on the film surface is proposed. The predictions from the model give fairly good agreement with the experimental data. 相似文献
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体热源沸腾池的建模及其验证 总被引:1,自引:0,他引:1
在事故保护系统和自动停堆系统失效的假设下,快堆中一大类事故可能会发展到熔融池和沸腾池阶段,此阶段的特征是:液态钢和液态燃料为池内主要成分,以燃料的裂变热为体热源,整个池子被附着在冷壁面上的UO2固化壳包裹,当其中钢的温度超过沸点时,便开始沸腾。建立了一个半经验模型来描述体热源沸腾池的行为。模型中,用漂移速度模型来预测空泡份额分布,用修正后的Greene关系式计算平均传热系数并在此基础上根据实验结果确定局部传热系数,用焓方法求解包裹沸腾池的固化壳的温度场及厚度。对SCARABEE BF2实验(单组分UO2沸腾池)及BE+2(UO2 钢混合沸腾池)进行了模拟计算,计算结果与实验结果基本吻合。 相似文献
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为计算液态铅铋(LBE)在环管内不同加热环境下的湍流换热,基于开源计算流体力学程序OpenFOAM开发了四方程模型求解器4eqnFoam。将LBE在平板和圆管内的预测结果与直接数值模拟结果和实验结果进行对比,验证了求解器的有效性。基于该求解器,分别计算了LBE在外壁绝热内壁加热以及内外壁面等热流加热环管内不同雷诺数下的湍流换热量。结果表明:随着雷诺数的增加,两种加热条件下的无量纲温度脉动、雷诺热流、湍流热扩散作用增大,而平均湍流普朗特数减小;当雷诺数增加到一定程度时,平均湍流普朗特数变化不明显。基于4eqnFoam求解器,可为计算LBE热工水力现象提供更多参考。 相似文献