摘 要：近年来，超大规模集成电路及微电子机械系统( MEMS) 的迅猛发展，使得芯片集成度的不断提高。然而其很大程度上要受到因电子元器件发热而引起的热障所限制，这就使得对高性能冷却技术的需求提到了前所未有的层面。在此方面的不断追求探索，促成了一系列新型冷却方法的建立。微加工技术的进步使得在高热导率固体基体上加工出更多复杂的微结构成为可能。本文将研究在微通道内敷设微型针肋阵列，使流体横掠微型针肋阵列而冷却热沉的一种强化传热结构，以揭示横掠微针肋针肋阵列热沉内流体流动与传热特性。
本文以去离子水为工质，选取了不同高径比、不同排布形式的圆形针肋热沉，对其流动与传热特性进行了实验研究，并对不同排布形式的微针肋内部的流动进行了数值模拟。
研究表明：针肋的布置方式对阻力特性的影响很大，在小流量下其影响较小，随着流量的增加影响越显著；高径比影响摩擦阻力系数，当针肋高径比为1和1.5时，压力降随流体流量的变化相对较小,且结构较利于流动；当Re数大于500时，摩擦阻力系数接近常数；端壁效应的存在增大了摩擦阻力系数。
其次，关于微针肋热沉的传热特性，研究表明：在小流量时，流量的改变对底板温度的影响较大；随着流量的增大，平均对流换热系数增加，但曲线的斜率有所变小；Re数对热沉换热性能的影响非常显著；随流量的不断提高，不同加热功率之间的总热阻值并没有太大的区别；端壁效应的存在增大了Nu数对Re数的依赖。
最后对微针肋热沉的流动进行了数值模拟，模拟值和实验值能有较好的吻合。层流模型可以用来模拟低雷诺数下的横掠微针肋热沉的流动与传热问题。可以对低雷诺数下微针肋阵列内部流动特性进行估算。
关键词：微针肋;微通道；热沉；流动与传热
Abstract：In recent years, the rapid development of VLSI and MEMS makes the continuous improvement of chip integration. However, that is largely limited by the thermal barrier caused by the heat generated by electronic components. This makes the demand for high performance cooling technology referred to an unprecedented level. The constant pursuit of exploring in this regard leads to the establishment of a series of new cooling methods. The advances in micro-fabrication techniques make fabricating a complex microstructure in high-thermal-conductivity solid substrates possible. This paper will examine the arranged inside a rectangular micro channel a microscale cooling method: force convection across micro pin fin heat sinks to clarify some mechanisms about flow resistance and heat transfer through micro pin fin heat sinks. This paper experimental and simulation investigate on flow resistance and heat transfer characteristics associated with the forced flow of de-ionized water through circular shaped micro pin fins with different sizes at staggered and in-line arrays.
It has found that the arrangement of pin fins have a significant effect on the pressure drop. The effect is little at low flow volume, but increases with the increasing flow volume. The pin-fin height-to-diameter has influence on the friction factor: the influence of the fluid flow to the pressure drop is relatively small, when the height and diameter ratio of pin fin is 1 and 1.5. And this structure is more conductive to flow. When Re>500, the friction coefficient is close to constant. Endwall effects bring higher flow resistance.
Secondly, heat transfer characteristics over micro pin-fin bundles have been experimentally investigated．It is shown that the influence of the flow change to the temperature at the bottom of the section is major, when the flow is small. As the flow increases, the average convective heat transfer coefficient increased, but the slope of the curve has become smaller. Reynolds numbers produces a significant impact on heat transfer performance of heat sink. With the continuous improvement of flow, there is no much difference between the total thermal resistances at different heating power. The existence of endwall effects makes Nusselt numbers more dependent on Reynolds numbers.
At last，flow resistance characteristics have been numerically simulated．It is shown the simulation value and experimental value have a good match．Laminar flow model can be used to simulate flow resistance and heat transfer problem at the low Reynolds number．Flow characteristics in low Reynolds number can be estimated within micro pin-fin bundles.
Key words: Micro pin fins; Micro channel; Heat sink; Flow and heat transfer
