Numerical Calculation of the Peaking Factor of a Water-Cooled W/Cu Monoblock for a Divertor

In order to accurately predict the incident critical heat flux (ICHF, the heat flux at the heated surface when CHF occurs) of a water-cooled W/Cu monoblock for a divertor, the exact knowledge of its peaking factors (fp) under one-sided heating conditions with different design parameters is a key issue. In this paper, the heat conduction in the solid domain of a water-cooled W/Cu monoblock is calculated numerically by assuming the local heat transfer coefficients (HTC) of the cooling wall to be functions of the local wall temperature, so as to obtain fp. The reliability of the calculation method is validated by an experimental example result, with the maximum error of 2.1% only. The effects of geometric and flow parameters on the fp of a water-cooled W/Cu monoblock are investigated. Within the scope of this study, it is shown that the fp increases with increasing dimensionless W/Cu monoblock width and armour thickness (the shortest distance between the heated surface and Cu layer), and the maximum increases are 43.8% and 22.4% respectively. The dimensionless W/Cu monoblock height and Cu thickness have little effect on fp. The increase of Reynolds number and Jakob number causes the increase of fp, and the maximum increases are 6.8% and 9.6% respectively. Based on the calculated results, an empirical correlation on peaking factor is obtained via regression. These results provide a valuable reference for the thermal-hydraulic design of water-cooled divertors.     

离心力场下多孔介质中的热驱动现象

基于涡轮叶片新型超级冷却技术,在具有冷却通道的新型冷却结构中加入多孔介质,采用数值模拟方法研究了新型冷却结构的热驱动现象,计算结果和实验结果基本一致。研究结果表明在新型冷却结构中加入多孔介质后,封闭腔体中仍然发生了热驱动流动。而且通过数值模拟获得的流场和温度场,进一步地研究封闭腔体中流体的流动和换热过程。     

基于Mie理论分析离散颗粒包裹尾喷流红外消光特性

针对离散颗粒红外消光特性,利用Mie理论开展最佳干扰(消光)粒径和最佳粒径下的颗粒浓度与透过率关系的研究,在此基础上结合某典型飞机喷流参数,从理论上探讨、分析了两种离散颗粒材料环高温尾喷流喷射后的红外透过率(3 μm).研究成果对于进一步选择、研究、制备低红外透过率的离散颗粒材料提供了一套有价值的理论预估评价方法.     

Numerical Simulation on Subcooled Boiling Heat Transfer Characteristics of Water-Cooled W/Cu Divertors

In order to realize safe and stable operation of a water-cooled W/Cu divertor under high heating condition,the exact knowledge of its subcooled boiling heat transfer characteristics under different design parameters is crucial.In this paper,subcooled boiling heat transfer in a water-cooled W/Cu divertor was numerically investigated based on computational fluid dynamic(CFD).The boiling heat transfer was simulated based on the Euler homogeneous phase model,and local differences of liquid physical properties were considered under one-sided high heating conditions.The calculated wall temperature was in good agreement with experimental results,with the maximum error of 5%only.On this basis,the void fraction distribution,flow field and heat transfer coefficient(HTC)distribution were obtained.The effects of heat flux,inlet velocity and inlet temperature on temperature distribution and pressure drop of a water-cooled W/Cu divertor were also investigated.These results provide a valuable reference for the thermal-hydraulic design of a water-cooled W/Cu divertor.     

IGBT模块功率循环疲劳寿命预测

随着IGBT功率模块的广泛应用,其功率循环可靠性问题得到关注和重视.介绍了模块的功率循环失效机理,指出铝键合线剥离是模块功率循环失效的原因;基于有限元法计算了模块在功率循环过程中的温度分布与变化,并在此基础上计算了模块的应力应变:根据应力应变数值的计算结果,分别采用应变能法和应变法等两种疲劳破坏准则,预测了键合线疲劳寿命.研究表明,铝键合线根部为模块的疲劳危险区:随着芯片热损耗的增加,芯片结温变化幅度的增加,功率模块疲劳寿命急剧地减小.     

发散孔纵向波纹隔热屏气膜冷却特性研究

对燃烧室内开有发散孔的纵向波纹隔热屏进行了数值模拟。研究隔热屏的四种结构参数开孔率、波纹板高度、气膜孔直径和冷却通道高度的改变对隔热屏冷却效果的影响。研究表明：在气膜孔出流总量相同的情况下,3％开孔率比6％开孔率的隔热屏平均冷却效率较高;汉纹板高度对隔热屏冷却效果影响较大,波纹板无量纲高度B=1％时的隔热屏平均冷却效率最高;冷却通道高度和气膜孔直径对隔热屏冷却效果影响较小,冷却通道高度只影响隔热屏前段的冷却效率,发散孔气膜孔直径的大小则对隔热屏冷却效率几乎没有影响。