矩形肋片散热器几何参数对散热的影响分析

为考察矩形肋片散热器几何参数对散热效果的影响规律,文中应用热仿真分析软件Flotherm对矩形肋片散热器在不同结构参数下的模型进行了自然对流散热计算,通过对比分析不同模型的温度和热阻计算结果,探讨了散热器基板参数和肋片参数对其散热性能的影响。分析表明,改变散热器肋片的高度、长度和间距可有效降低散热器的热阻。这些几何参数可以作为散热器热设计变量,以进一步对散热器进行优化设计。     

精密机床床身结构参数的优化设计

在确定精密机床床身合理结构的基础上，利用ANSYS有限元软件提供的APDL参数化设计语言和优化设计方法，以床身的肋板布置和肋板厚度为设计参数，对床身进行结构设计参数的优化，确定了床身结构的合理参数。不仅大大提高了床身的动态性能，而且节省了材科，降低了生产成本。     

弯矩作用下肋的分布对肋板的振动影响

加强肋旨在降低薄板结构的振动,研究肋的交叉分布、横分布、纵分布、肋截面参数、板厚因素的变化对振动的影响,通过正交试验,利用有限元法对一两端固支的矩形加肋板进行频率响应有限元分析,计算从1～200 Hz的响应,得到评定薄板振动量的大小。算例表明,在肋的质量不变的情况下,采用横向布置,肋的截面为15 mm×20 mm,板厚为0.014 m时振动量最小。运用正交试验、有限元法、虚拟试验相结合的方法处理具体的数据,避免庞大的实物试验所需要的高成本。     

CPU散热器结构设计与热分析

CPU散热器是将CPU核心热量迅速导出的关键,已成为获得新一代电子芯片的主要问题之一。采用数值模拟方法对放射状太阳花CPU散热器进行三维流场及温度场分析,探讨放射状散热器在不同的肋片形状、肋片数N和肋片厚度等各种不同的参数作用下,对于整体散热器散热和流动性能的变化与影响,同时分析了太阳花散热器自然对流和瞬时动态特性。     

基于响应面法的薄壁机匣加筋肋优化设计

加筋肋是提高薄壁机匣刚度普遍采用的结构形式,合理的加筋肋形式及位置可以起到抑制薄壁机匣振动的效果。采用有限元法对某型航空发动机加筋肋薄壁机匣模型振动特性进行分析计算,并利用锤击法对其进行模态试验,通过结果分析验证了计算结果的准确性。研究加筋肋位置和截面几何参数变化对机匣固有频率的影响;采用响应面法对加筋肋位置进行优化设计,通过有限元验证优化结果的准确性。分析表明在保证质量不变的情况下,加肋结构减振效果明显。     

加肋圆柱壳参数化建模与稳定性分析

加肋圆柱壳是鱼雷以及水下航行器较常采用耐压壳体形式。壳体除需满足一定的强度要求外,稳定性也是十分重要的一个方面。本文采用参数化建模的方法,利用ANSYS中的梁、壳单元,使用组合建模的方法进行加肋圆柱壳的建模,在保证足够精度的同时简化了建模减小了计算量。使用APDL语言编制了加肋圆柱壳的非线性屈曲分析程序,对稳定性进行了分析,并与理论计算的结果进行了比较。结果显示此方法具有较高的精度,具有实际应用价值。     

肋片对于发动机推力室再生冷却的影响研究

为更好地对发动机推力室结构段进行热防护以避免由于温度过高所导致的结构破坏,以发动机推力室结构段为研究对象,利用Fluent软件对不同冷却情况进行数值模拟,分析有无肋片及肋片深宽比等参数变化对室壁冷却情况的影响。结果表明,肋片有助于对室壁进行冷却,肋片深宽比的增加会提高肋效率,但是会削弱冷却剂与推力室内壁面间的对流换热,因此需根据实际工况,试验确定最佳深宽比及肋片个数。     

涡轮冷却叶片参数化建模方法

针对航空发动机涡轮冷却叶片结构复杂、设计难度高的问题,采用UG/API的特征参数化建模技术与数学解析相结合的方法,建立了面向工程的流程化先进涡轮冷却叶片模块式参数化建模系统。从特征与参数的角度,对涡轮冷却叶片进行了叶身外形特征、内部冷却特征以及独立附属结构特征的划分。给出了叶身外形、榫头、缘板和叶身内形以及以其为基体的换热肋片、隔肋、扰流柱特征的详细参数化建模过程及设计实例,提高了涡轮冷却叶片设计效率。     

航空发动机叶片竹节孔加工及传热分析

介绍了一种利用电解加工法在航空发动机叶片上加工带肋冷却孔(竹节孔)的工艺方法,对其加工设备和电极制作过程进行详细的描述。实验同时分析了加工参数如加工电压、电解液种类和浓度、加工材料等对冷却孔成形的影响。并结合有限元方法,研究了竹节孔对涡轮叶片冷却效果的改善,对影响传热的参数,如传热系数与努赛尔数Nu进行了分析。     

SolidWorks中基于国标画法的法兰剖视图生成

针对工程制图课程中利用三维图形软件绘制剖视图时会出现不符合机械制图国标规定画法的问题,研究了法兰盘剖视图的生成方法。首先基于SolidWorks的VBA开发工具,编程自动搜索并获取法兰上圆孔、肋板的坐标参数,绘制经过圆孔和法兰中心的剖切线,设置剖切深度,生成包含圆孔轮廓线的剖视图;然后根据肋板参数添加肋板轮廓线以及圆孔中心线,生成了符合国标画法的法兰剖视图。     

水冷盘式制动器散热结构优化

为提高水冷盘式制动器散热性能,基于强化对流传热原理,通过添加扰流柱对制动器散热结构进行优化,设计了4种扰流柱散热结构,运用CFD方法模拟制动盘流固耦合传热过程,采用Fluent软件进行热流固耦合仿真计算,获得制动盘温度特性和换热特性以及流动阻力特性,并使用综合性能评价因子对不同扰流柱散热结构进行评价。结果表明:通过在安装盘水槽内添加扰流柱可以有效地提高水冷盘式制动器的散热效果;在相同的工作条件下,正三角形扰流柱散热结构的盘面温度最低,平均努塞尔数与流动阻力最高,其综合散热性能较圆形、椭圆形以及水滴形扰流柱散热结构分别提高了3.4%,2.4%和4.4%,较无扰流柱散热结构提高了6.7%,正三角形扰流柱散热结构具有更好的综合散热性能。研究结果为水冷盘式制动器散热结构的优化设计提供了参考。     

基于ICEPAK仿真的散热器结构热设计研究

文中利用ICEPAK软件对多密度高功率芯片散热器结构进行了热设计研究。研究确立了影响翅片散热器散热性能的关键尺寸设计参数,如基板厚度、翅片高度、翅片厚度和翅片间距等,并得出了各尺寸设计参数对其散热效果的影响趋势,确定了散热器结构的最佳布局方案。此外,研究还建立了最佳布局的散热器结构实物并进行了高低温试验以模拟其高温散热情况。通过实验数据对比发现,仿真计算结果与实际较为吻合,进而验证了ICEPAK软件在电子设备散热设计方面的准确性与可靠性。     

Experimental and CFD analysis of heat sinks with base plate for CPU cooling

Experimental and theoretical investigations of the thermal performance of a variety of heat sinks have been made. The heat sinks investigated were: straight finned, elliptical finned, small pin finned, circular disc finned, elliptical disc finned, frustum finned and double base straight finned. Realistic, manufacturable geometries are considered for minimizing thermal resistance at low velocity. The experimental results of several of the simple geometry heat sinks have been compared to those predicted by a commercially available computational fluid dynamics code fluent. The parameters such as fin geometry, fin pitch and fin height are optimized primarily in this paper and a second task is carried out to optimize base plate thicknesses, base plate materials and modify design of heat sink for improving the thermal performance in the next generation. Although the performance of heat sink is good, the temperature of heat sink at center is high. In this research work, the best heat sink geometry is selected and modified in order to reduce maximum temperature distribution and hot spots of heat sink at center by changing the geometry design and adding one more base. It is observed that flow obstructions in the chassis and the resulting air recirculation affect the heat sink temperature distribution.     

Shape Optimization of a plate-fin type heat sink with triangular-shaped vortex generator

In this study the optimization of plate-fin type heat sink with vortex generator for the thermal stability is performed numerically. The optimum solutions in the heat sink are obtained when the temperature rise and the pressure drop are minimized simultaneously. Thermal performance of heat sink is influenced by the heat sink shape such as the base-part fin width, lower-part fin width, and basement thickness. To acquire the optimal design variables automatically, CFD and mathematical optimization are integrated. The flow and thermal fields are predicted using the finite volume method. The optimization is carried out by means of the sequential quadratic programming (SQP) method which is widely used for the constrained nonlinear optimization problem. The results show that the optimal design variables are as follows ; B₁=2.584 mm, B₂=1.741 mm, and t=7.914 mm when the temperature rise is less than 40 K. Comparing with the initial design, the temperature rise is reduced by 4.2 K, while the pressure drop is increased by 9.43 Pa. The relationship between the pressure drop and the temperature rise is also presented to select the heat sink shape for the designers.     

活塞结构对其传热及强度的影响分析

以一款满足国Ⅴ排放限值的高压共轨柴油机活塞为研究对象,采用硬度塞测温法试验测试分析了标定功率工况下活塞稳态温度场分布和热负荷的大小,结合温度场试验测试结果建立了内冷油道与活塞的流固耦合传热数值仿真模型,仿真分析了活塞销座长度、销孔直径、火力岸高度、同侧回油孔中心间距4个活塞结构参数对活塞传热与结构强度的影响。研究结果发现,活塞的火力岸、内冷油腔、回油孔和销孔处的热流密度较大并出现应力集中。选择活塞销座长度、销孔直径、火力岸高度、同侧回油孔中心间距4个参数,进一步研究活塞结构对其传热及结构强度的影响特征。结果显示,活塞的每个结构参数值改变不仅会较大程度地改变该处的传热性能和应力分布,还会导致其他关键点的应力和温度发生改变,这使得活塞结构修改需更加谨慎。适当增加销座长度、销孔直径和火力岸高度,减小同侧回油孔中心间距,可以改善活塞的受热,也可以降低活塞的整体应力。     

Forced air cooling by using manifold microchannel heat sinks

A study of manifold microchannel (MMC) heat sinks for forced air cooling was performed experimentally. The manifold microchannel heat sink differs from a traditional microchannel (TMC) heat sink in that the flow length is greatly reduced to a small fraction of the total length of the heat sink. In other words, the MMC heat sink features many inlet and outlet channels, alternating at a periodic distance along the length of the microchannels while the TMC heat sink features one inlet and one outlet channels. The present study primarily focused to investigate the effects of geometrical parameters on the thermal performance of the manifold microchannel heat sinks for optimal design. Also, the thermal resistances of the MMC heat sinks were compared with those of the TMC heat sinks. Experimental results showed the thermal resistances of MMC heat sinks were affected strongly by the pumping power, the microchannel width and the manifold inlet/outlet channel width, but weakly by the microchannel thickness-width ratio and the microchannel depth coorporated with the manifold inlet/outlet channel width. However, it was found that there existed the optimum values of the latter parameters. Under the optimum condition of geometrical parameters in the present study, the thermal resistance of the MMC heat sink was approximately 35% lower than that of a TMC heat sink, which clearly demonstrated the effectiveness of using a manifold.     

超级计算机机箱的热流场特性研究和优化设计

采用计算流体力学(CFD)方法研究机箱在强制对流条件下的流场和热场特性。对影响机箱温度的元件布局、平板散热器结构、气流通道净空间距、环境温度等因素进行了研究和优化,获得了芯片温度对翅间距、翅厚、风道净空间距、环境温度的量化依赖关系;总结出了以上参数的优化值以及平板散热器翅间距和翅厚设计的经验值范围。     

海拔高度对变频器散热影响的研究

根据高海拔地区空气的流动特点,引入海拔高度参数。结合不同海拔高度空气特性对散热器温度的影响,对文献[11]提出的板翅式散热器对流换热系数关联式做了修正。根据修正后的关联式计算了散热器出风口空气平均温度和散热器平均压降。修正后的理论计算结果与仿真结果的相对误差小于5％,表明该修正合理。文中的结果可为高海拔地区变频器等电气产品的热设计和可靠性评估提供计算方法和参考数据。     

大容量电力电子装置中板式水冷散热器的优化设计

为提高水冷散热器的散热能力、控制其温度均匀性,在散热器外形尺寸及流量一定的条件下,从理论上对层流范围内平板式水冷散热器的三个通道参数(通道数、散热片高度、散热片占空比)与散热器量纲一散热热阻的变化关系进行了推导。提出可根据这些变化关系来对任意尺寸平板式水冷散热器的各通道参数进行优化选择,在工程设计上具有很好的指导意义,仿真和试验结果证明了方法的有效性并表明:小通道尺寸的平板式水冷散热器对于解决大热流密度器件的散热更为有效,散热效率更高;在同样的参数情况下,流量增大则散热器效率降低,应综合考虑散热器流阻和流体平均温升的控制要求来选择流量。     

Effect of Internal Cooling on Tool-Chip Interface Temperature in Orthogonal Cutting

A numerical method to study the effect of internal heat sink variables on the tool-chip interface temperature in orthogonal cutting was presented. The analytical method is based on two main assumptions that the chip can be treated as a semi-infinite body with a moving heat source at the tool-chip interface and the tool can be treated as a semi-infinite body with a stationary heat source at the tool-chip interface and a uniform plane heat sink inside the semi-infinite body. An approach using the point heat partition coefficient is employed to obtain the tool-chip interface temperature distribution. The temperature distributions along the tool-chip interface with different heat sink intensities, heat sink distances from the tool-chip interface, and heat sink areas were presented. The effects of the heat sink intensity, heat sink distance from the tool-chip interface, and heat sink area on the tool-chip interface temperature were investigated. It was found that the internal cooling with a heat sink in the cutting tool could greatly affect the tool-chip interface temperature.