转子结构对风扇性能和内部流动的影响研究

发布时间：2018-01-20 08:01

本文关键词： 小型轴流风扇大涡模拟轮毂比双层反转风扇噪声　出处：《浙江理工大学》2011年硕士论文　论文类型：学位论文

【摘要】：随着电子产品的不断小型化和高性能化,对影响其性能和寿命的决定因素—小型换热风扇的性能提出了更高的要求,如何设计出低噪声、高通量和结构紧凑的小型换热风扇是人们研究的主要问题。本文选取Sunon公司的AC风扇系列产品型号为SF23092A和SF23080AT的小型轴流风扇作为研究对象,通过数值模拟计算分析了小型轴流风扇共有的静特性和内部流动特性,结合试验测量验证了型号为SF23092A风扇全压性能曲线的模拟结果的可靠性,进而在这个基础上研究不同轮毂比和叶片数情况下的风扇模型,分析它们的静特性、内部流场及声场分布,结果表明尽管风扇模型的气动性能有所改善,但存在性能改善不明显或噪声增加的问题,并不能满足目前对小型轴流风扇提出的高性能要求,因此进一步研究了双转子风扇的两种模型,发现双层反转风扇的优良特性能够很好的满足这种要求。首先利用激光式三坐标测量臂获得的叶片几何数据在UG中逆向建模获得风扇的几何模型,用Gambit软件里的Turbo模块建立风扇的流道并划分网格,采用RNG k-ε湍流模型进行定常流动的模拟,通过比较全压性能曲线的试验结果和模拟结果来验证数值模拟计算的可靠性。同时经过对比分析两款不同型号的风扇,总结出小型轴流风扇静特性和内部流动的共同点,为进一步的研究打下基础。其次,针对SF23092A小型轴流风扇模型,研究轮毂比和叶片数对风扇气动性能的影响。其中对于不同轮毂比风扇模型的数值计算分三步进行,首先采用标准的k-ε湍流模型进行定常流动的模拟,然后将定常压力场作为大涡模拟LES的初场计算非定常压力场,在压力场动能稳定后基于LES采用精确的Ffowcs williams—Hawkings方程计算声场,将时域谱应用FFT对计算得到的声压信号进行处理,保证了声压信号的准确性和可靠性。根据数值计算结果,对比分析不同轮毂比风扇的静特性、噪声功率谱密度分布、噪声声压级分布以及噪声声压级衰减的趋势。分析叶片数对风扇性能影响时,采用RNG k-ε湍流模型进行定常流动的模拟,得出叶片数为5时与本文确定的转速、叶片安装角、叶面弦长相匹配。最后,初步探讨了在较小的空间里实现高压比、高效率并有利于通风的风扇模型—双层反转风扇。经过数值计算分析,双层反转风扇可以获得远大于两倍的单转子风扇所能得到的全压,而且效率也不会比单转子效率低,因此采用此种风扇来使流体获得更多的压力能,进而获得高通风量是可行的。本文致力于如何设计出低噪声、高通量和结构紧凑的小型换热风扇进行了一定的探索研究,希望对改善小型轴流风扇的性能以及优化设计的研究提供一定的理论支持。
[Abstract]:With the continuous miniaturization and high performance of electronic products, the performance of small heat exchanger fan, which is the decisive factor that affects its performance and life, has been put forward higher requirements, how to design low noise. High-throughput and compact small heat transfer fans are the main problems studied by people. In this paper, Sunon AC fan series product model is SF23092A and SF23080AT small axial flow fan as the research object. The static characteristics and internal flow characteristics of the small axial fan are analyzed by numerical simulation. The reliability of the simulation results of the full-pressure performance curve of the SF23092A fan is verified by the experimental measurement. On this basis, the fan models with different wheel / hub ratio and blade number are studied, and their static characteristics, internal flow field and sound field distribution are analyzed. The results show that the aerodynamic performance of the fan model is improved. However, the performance improvement is not obvious or the noise is increasing, which can not meet the high performance requirements of the small axial flow fan. Therefore, two models of double rotor fan are further studied. It is found that the excellent characteristics of the double-layer reversal fan can meet this requirement very well. Firstly, the geometry model of the fan is obtained by using the geometry data of the blade obtained by the laser coordinate measuring arm in UG. The flow channel of fan is built with Turbo module in Gambit software and the flow is meshed. The steady flow is simulated by RNG k- 蔚 turbulence model. The reliability of the numerical simulation calculation is verified by comparing the experimental results of the full pressure performance curve and the simulation results. At the same time, two different types of fans are compared and analyzed. The common points of static characteristics and internal flow of small axial fan are summarized, which will lay a foundation for further research. Secondly, the influence of wheel hub ratio and blade number on fan aerodynamic performance is studied for SF23092A small axial fan model. The numerical calculation of different hub ratio fan model is divided into three steps. At first, the standard k- 蔚 turbulence model is used to simulate the steady flow, and then the unsteady pressure field is calculated by using the steady pressure field as the initial field of the large eddy simulation LES. After the kinetic energy of the pressure field is stabilized, the sound field is calculated by using the accurate Ffowcs williams-Hawkings equation based on LES. The time domain spectrum is used to process the calculated sound pressure signal with FFT to ensure the accuracy and reliability of the sound pressure signal. According to the numerical results, the static characteristics of the fan with different hub ratio are compared and analyzed. The distribution of noise power spectrum density, noise sound pressure level and the attenuation trend of noise sound pressure level. RNG k- 蔚 turbulence model is used to simulate steady flow when the influence of blade number on fan performance is analyzed. The results show that the number of blades at 5:00 matches the rotational speed, blade mounting angle and blade chord length determined in this paper. Finally, a fan model with high pressure ratio, high efficiency and good ventilation in a small space is preliminarily discussed. The double layer reverse fan can obtain the full pressure of the single rotor fan which is more than twice as high as the single rotor fan, and the efficiency is not lower than that of the single rotor fan. Therefore, this fan is used to make the fluid obtain more pressure energy. It is feasible to obtain high ventilation. This paper focuses on the design of low-noise, high-throughput and compact small heat transfer fan for a certain amount of exploration. It is hoped to provide some theoretical support for improving the performance of small axial fan and the research of optimization design.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH43

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