Simulation, experimentation, and collaborative analysis of adjacent heat exchange modules in a vehicular cooling system

A cooling system consisting of several heat exchange modules is a necessary part of an automobile, and its performance has a direct effect on a vehicle’s energy consumption. Heat exchangers, such as a charged air cooler (CAC), radiator, oil cooler, or condenser have different structures and can be arranged in various orders, and each combination may produce different effects because of interactions among them. In this study, we aimed to explore the principles governing interactions among adjacent heat exchangers in a cooling system, using numerical simulation and experimental technology. 3D models with different combinations were developed, compared, and analyzed comprehensively. A wind tunnel test platform was constructed to validate the computational results. We found that the heat dissipation of the modules was affected slightly by their relative position (the rules basically comply with the field synergy principle), but was independent of the modules’ spacing within a certain distance range. The heat dissipation of one module could be effectively improved by restructuring, but with a penalty of higher resistance. However, the negative effect on the downstream module was much less than expected. The results indicated that the intensity of heat transfer depends not only on the average temperature difference between cold and hot mediums, but also on the temperature distribution.     

Numerical investigation of the power generation of a ducted composite material marine current turbine

In the hostile and highly corrosive marine environment,advanced composite materials can be used in marine current turbines due to their high strength-to-weight ratios and excellent resistance to corrosion.A composite material marine current turbine(CMMCT),which has significant advantages over traditional designs,has been developed and investigated numerically.A substantial improvement in turbine performance is achieved by placement of a duct to concentrate the energy.Computational fluid dynamics(CFD) results show that the extracted power of a ducted CMMCT can be three to four times the power extracted by a bare turbine of the same turbine area.The results provide an insight into the hydrodynamic design and operation of a CMMCT used to shorten the design period and improve technical performance.     

基于CFD的螺旋槽干气密封槽型参数的优化

运用fluent软件对不同气膜厚度的螺旋槽干气密封内部微间隙三维流场进行数值模拟,得到它们流场的压力分布。通过不同厚度的气膜所产生的动压来获得它们气膜推力,再利用最小二乘法则拟合得到了气膜推力关于气膜厚度的解析式,最后求得气膜刚度,以最大气膜刚度为目标,对螺旋槽的槽深和螺旋角进行了优化。结果表明:气膜刚度是关于气膜厚度的负指数函数;在本例中,当槽深为7.5μm、螺旋角为75°时气膜刚度最大,该优化程序为干气密封的优化设计提供理论基础。     

游泳运动技术优化与创新的研究

运用运动生物力学、流体力学、程序设计等研究方法，为游泳技术研究提供了一个多元化的诊断方法，提出了游泳技术训练与技术研究可操作的程序化模式，搭建了游泳技术研究与高科技结合的应用渠道，保障了重点运动员的技术训练与技术研究。在研究方法和应用实践研究方面具有一定的创新性。     

上海地铁2号线车厢气流组织分析

为研究用数值模拟方法分析地铁车厢环境的可行性,通过实测得到上海地铁2号线的车厢内温度和风速数据,利用CFD模拟其车厢气流组织。通过调整送风温度、送风速度和客流密度,得到满足人体舒适度的最佳送风参数:夏季满载时,送风温度为20℃,送风速度为1.53 m/s;夏季超载时,送风温度为17℃,送风速度为2 m/s。本文形成了研究地铁车厢环境的完整体系,为上海地铁车厢气流组织优化设计以及舒适性研究提供参考。     

压水堆燃料棒束新型定位格架的数值分析

定位格架是反应堆燃料组件中较为重要的部分,带搅混叶片的AFA-2G/3G定位格架具有良好的支撑燃料棒束和强化棒束通道换热的性能,但结构复杂,加工难度大。设计一种制造工艺相对简单的带有矩形涡旋发生器（longitudinal vortex generators,LVGs）的新型定位格架,研究当此种定位格架用于5×5的燃料棒束时的热工水力特性。主要采用标准k-ε湍流模型和增强型壁面函数处理方法,分析雷诺数和LVGs攻角对流体换热的影响。结果表明：由LVGs产生的二次流扩散到下游区域并对燃料棒的边界层产生扰动,增强换热;60°和45°攻角的矩形涡旋发生器（RLVGs）的换热效果几乎相同,但60°攻角RLVGs的阻力和压降较大。本研究对这种新型燃料组件的工程设计具有一定的参考价值。     

翼型涡轮内部流场CFD数值模拟

本文利用计算流体动力学（CFD）对一种涡轮电机的内流场作了较详细的三维数值模拟,得出了较详细的涡轮内部流场,分析了涡轮叶片结构对流场的影响,同时在此基础上分析了涡轮的特性,为涡轮电机的性能预测和结构改进提供了有力的依据。     

基于CFD的竖直U型地埋管换热器传热性能仿真分析

利用CFD软件Fluent的前处理软件Gambit建立与实际系统相同的单U竖直地埋管换热器的三维非稳态传热模型,进行传热模拟仿真,通过得出的地能井与U型管中温度的变化图形来分析温度变化趋势,并与实验测试结果进行比较,结果表明,实验值和仿真结果很接近。这有利于掌握在没有预先埋好热电偶的情况下去观察地能井温度的变化。     

CFD Simulation of Film Flow and Gas/Liquid Countercurrent Flow on Structured Packing

A mathematic model of two-phase flow and a physical model of two-dimensional (2D) vertical section for the plate-type structured packing Mellapak 250.Y were set up and verified. The models were used to study the influence of packing’s surface microstructure on the continuity of liquid film and the amount of liquid holdup. Simulation results show that the round corner shape and micro wavy structure are favorable in remaining the continuity of liquid film and increasing the amount of liquid holdup. The appropriate liquid flow rate was determined by investigating different liquid loadings to obtain an unbroken liquid film on the packing surface. The pressure difference between inlet and outlet for gas phase allowed gas and liquid to flow countercurrently in a 2D computational domain. The direction change of gas flow occurred near the phase interface area.     

Numerical investigation on thermal properties of micro-pin-fin cooler

Micro-pin-fin cooler mounted on the power chip enables the heat removal to meet modern microsystem requirement. Carbon nanotubes (CNTs) have been proven as a potential material for micro-coolers due to the superior thermal conductivity, good mechanical property and so forth, and there appear various applications of CNTs in the micro-cooler technology. In the present paper, an analysis of the thermal and hydraulic characteristics of the micro-pin-fin heat sink was conducted, where air was used as the cooling medium and an impinging jet was introduced to enhance the heat transfer. Three-dimension computational fluid dynamics (CFD) simulations were carried out for micro-pin-fin coolers with various parameters, including the pin-fin size and pattern as well as the jet velocity and nozzle diameter. The flow field and thermal properties of the micro-pin-fin heat sink were obtained, and the heat removal efficiency was evaluated.