外文翻译----冷却系统技术的发展趋势.docx

附录1冷却系统技术的发展趋势大流量和高静压的新技术: 对旋式风机yoshihiko aizawa随着世界核心技术(信息技术)的飞速发展，在许多电子设备当中譬如说服务器、通信器材等以cpu和pdd为代表的固定设备不断出了的微型化趋势。这些设备在功能加的同时也伴随着散热的不断增加, 这种情况预计在未来一段时间里将会一直持续下去。与此同时, 在微型化迅速发展的前提下，设备的零件会以更大的密度集中安装一个基座上。结果,仅用一个风扇作为空气动力源做散热工作 ,很多情况下需要一种方案来改善散热较多，阻力系数比较大的设备的散热状况。如果要具体地解决这个问题, 就需要一种具有更大风压和流量的风扇。以前, 我们为用户们解决这种问题的方法通常是用一个大流量的风机和轴流风机联合工作，或者是用一个高压的风机配一台离心风机再一个就是用两台离心风机同时工作。但是, 在同时要求需要很大的流量和很高的风压的条件下，靠以前的两台风机联合工作是不能满足要求的，而且靠简单的改进原有风机的流量和风压；或者是修改叶轮叶片的设计方法和改变风机中电机的转速等都不能够达到这种要求。以前, 当风机生产商们面对这种需要大流量和高风压的顾客时, 他们就需要改进轴流风机的结构来增加它的风压或者是改进离心风机的结构来增加它的流量。因为轴流风机适合在一种阻力系数较低条件下用来冷却一个设备，它可以较容易的获得较大的风量，并且它可以适当地获得一定的风压。至于离心风机, 它不容易改进获得较大的流量但是却很容易获得较高的静态压力, 并且它适合在阻力系数较高的设备中工作。两种风机的结构和他们的特点详细的列于下表 (1)。对旋轴流风机是一种有两级叶轮并且叶轮转向相反的风机。这是比较传统的技术, 以前大多数被采取用于航空飞行器或者是直升机当中, 但是用来作为电子设备的冷却风扇的例子却很少。我认为主要原因是对旋轴流风机的噪声问题一直以来都没有被解决。而且有人认为对旋风机的输送距离不如同类型的两轴流风机。对旋轴流风机有两级叶轮，前后两级叶轮的旋转方向是相反的。在工作过程中，旋转方向不同的第二级叶轮接受从第一级叶轮出来的气流时，会将气流的旋转速度转化为轴向的压力（压力补充）。由于气流流经两级叶轮系统的转动时，两叶轮中间没有其他阻碍，大大减少了能量损失。本文描述了新形势下对高风压、大流量风机的需求，并且简单的改进以前的轴流风机或离心风机不能满足这种需要。在这种情况下，提出了对旋风机的方案。对旋风机能满足顾客以前所不能达到的高风压、大流量的要求。文中把对旋风机和过去的研究结果做了对比。这里我要感谢大家的努力。我不能充分地说明对旋轴流风机工作的原理，因为我没有仔细地对轴流风机的例子进行调查研究。我正在想继续对各种现象进行考察和研究，为将来推出新型的产品而努力。最后我引用了一位高级工程师的研究内容，但我希望大家能体谅我的不足和欠缺。参考文献(1) 由jsme 编辑, 机械工程handbook (1991) (2) sachio harada, fluid machine si unit version (1986), asakura shoten (3) yoshio kodama 等, 对旋轴流风机特征的实验性研究(动力学和噪声), jsme 国际学报, 60-576, b 1994-8 (4) yoshio kodama 等, 关于对旋轴流风机的流体特性的实验性研究, jsme 国际学报, 60-576, b 1994-8 (5) yoshio kodama 等, 对旋轴流风机的噪声研究 62-595, b 1996-3 附录2cooling system technology that changesthe conventional trendtechnology for large air volume and high static pressure : counter rotating fanyoshihiko aizawain electronic equipment such as servers and communicationdevices, which are the kernel of it (information technology) society, the miniaturization and improvement of the performance of the built-in parts represented by cpu and hdd are advancing at a marvelous speed. the heating value of these parts has also been increasing remarkably with the improvement of performance, which is expected to continue in the future. at the same time, miniaturization is one of the preconditions in this equipment and the mounting densities of parts arranged in the device chassis keep rising. consequently, also for an aerodynamic characteristic of a fan motor for internal cooling of a device, there have been an increasing number of cases where measures for an extremely high heating value and measures for an extremely high system impedance are required. to put it concretely, fan motors need to become larger in air volume andhigher in static pressure.in the past, the solution offered to customers was either ahigh air volume product with an axial flow fan or a high static pressure product with a centrifugal fan, or both together.however, in the case where the demand level of high air volume and high static pressure is extremely high as mentioned above and coexisting of both is also required, simply improving the existing high air volume or high static pressure products by reviewing the blade design or improving the rotating speed is not sufficient.in the past, fan makers, when faced with the demand forhigh air volume and high static pressure from customers, improved the performance of the axial flow fan when high air volume was needed or improved the centrifugal fan when high static pressure was needed. the axial flow fan is suitable for cooling a device with comparatively low impedance since it can easily obtain high air volume though static pressure obtained is not so high. as for the centrifugal fan, it is not easy to improve air volume but easy to obtain high static pressure, and it is suitable for a device with high impedance. each structure and their features areshown in table 1 (1).the counter rotating fan is a fan with the method of mutuallyrotating two moving blades in an opposite direction. this is a traditional technology, which has been adopted for use in aircrafts or helicopters, but examples of use as a cooling fan motor for electronic equipment are few. the main reason, i think, is that the weak point of the counter rotating fans loud noise could not be overcome until now. it has also been thought that it would not produce as much pressure as the axial flow fan in double stage in series with enough distance(1).the counter rotating axial flow fan is the kind of fan on which the driving blade with the shape that can receive the flow from the front driving blade smoothly is located in the back flow of the front driving blade to rotate it in an opposite direction of the front driving blade mutually. consequently, the swirl element of the flow can be converted into pressure (pressure recovery). also the collision loss, which is seen on the double stage in series fan, can be decreased. this text described how the new requests for future fanmotors are high air volume and high static pressure, and also that the past measures of simply improving the performanceof axial flow fan or centrifugal fan cannot satisfy it. next, an outline of the counter rotating fan was presented. the counter rotating fan is a new solution for customers who need unprecedented volume of high air and high static pressure.we have referred to the result of past research and the development documents for counter rotating fans in this article. i would like to express our gratitude here. we are not yet able to fully explain what is happening on compact counter rotating axial flow fan and one of the reasons is that we could not find an example of compact axial flow fan(so-called box fan) identical to those we are dealing with asa research object as far as we had investigated. we intend to continue the search for effective factors to the phenomenoninvestigation and the performance improvement, and to offer the market more epoch-making product in the future.finally, i have made an effort to quote the content ofthe description of our senior engineers correctly when thistext was brought together, but i humbly beg their pardonfor any parts that possibly lack accuracy.references(1) edited by jsme, mechanical engineering handbook (1991)(2) sachio h