基于数值模拟的单转子叶片结构对小型轴流风扇性能的影响

发布时间：2017-12-31 11:26

本文关键词：基于数值模拟的单转子叶片结构对小型轴流风扇性能的影响　出处：《浙江理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：小型轴流风扇是目前电子产品的主要散热设备,其性能直接决定电子产品的运行状况和使用寿命。随着电子产品向集成化、大功率化方向发展,散热需求日益增大,小型轴流风扇的通风性能和噪声性能越来越引起人们的重视。因此,非常有必要对小型轴流风扇进行结构优化,并开展对其静特性、气动噪声和内部流动特性的分析研究。本文以5叶片单转子小型轴流风扇为原型,通过改进单转子叶片结构分别设计出具有不同最大调制角位移的不等节距风扇和具有不同进口导叶出口角的进口导叶风扇。基于流场计算,在满足静特性要求的前提下选出降噪效果最好的不等节距风扇和进口导叶风扇,分别记作模型1和模型2,对比分析了原型、模型1和原型、模型2的静特性、气动噪声和内部流动特性,完成了原型、模型1、模型2静特性和噪声的实验测试。论文的主要内容及成果如下:(1)以5叶片单转子小型轴流风扇为原型,根据叶片角度调制法设计出13种具有不同最大调制角位移的不等节距风扇,根据进口导叶的设计要求设计出4种具有不同进口导叶出口角的进口导叶风扇;简述本文采用的数值模拟方法。(2)数值模拟的结果显示:在额定工况下,最大调制角位移等于6°的不等节距风扇和进口导叶出口角等于60°的进口导叶风扇在满足静特性要求的前提下具有最优的降噪效果,分别记作模型1和模型2。相比于原型,模型1的静特性基本保持不变,而模型2的静特性得到明显提升。(3)流场的研究结果显示:近场的噪声以离散噪声为主,主要由总压脉动引起,模型1和模型2均可以降低原型的近场离散噪声;远场的噪声以宽频噪声为主,与流场的涡量分布、涡量变化等因素有关,两种单转子叶片结构对原型的远场宽频噪声影响很小。(4)在风洞实验台上完成了原型、模型1和模型2的静特性实验。实验结果显示:数值模拟具有可靠性,最大调制角位移为6°的不等节距叶片没有明显改变原型的静特性,而安装出口角为60°的进口导叶将原型在额定工况下的静压提升了1.8Pa。(5)在半消声室中完成了原型、模型1和模型2的噪声测试。实验结果显示:相比于原型,模型1和模型2在风扇下游轴向上的最大降噪均位于距离风扇100mm的测试点,降噪分别达到1.5dB和1.2dB;对于距离风扇大于等于400mm的轴向测试点,优化模型的噪声与原型基本保持一致。综上所述,合理选择单转子小型轴流风扇叶片的不等节距分布方式可以在静特性基本保持不变的前提下降低近场的离散噪声,而安装具有适宜出口角的进口导叶不仅可以明显提升单转子小型轴流风扇的静特性,还能降低近场的离散噪声,改善内部流动特性。本文将对高静特性低噪声小型轴流风扇的单转子叶片结构优化提供依据。
[Abstract]:Small-sized axial fan is the main heat dissipation equipment of electronic products at present. Its performance directly determines the operation status and service life of electronic products. With the development of electronic products towards integration, high-power development. With the increasing demand for heat dissipation, people pay more and more attention to the ventilation performance and noise performance of the small axial fan. Therefore, it is very necessary to optimize the structure of the small axial fan and carry out its static characteristics. Analysis and study of aerodynamic noise and internal flow characteristics. This paper takes a small axial flow fan with a single rotor with 5 blades as the prototype. By improving the structure of single rotor blade, the different pitch fan with different maximum modulation angular displacement and the inlet guide fan with different inlet guide vane outlet angle are designed respectively. The flow field calculation is carried out. On the premise of satisfying the static characteristic requirements, the best noise reduction effect of unequal pitch fan and imported guide vane fan are selected, which are described as model 1 and model 2, respectively. The static characteristics of prototype, model 1 and prototype, model 2 are compared and analyzed. The prototype, model 1, model 2, static characteristics and noise are tested. The main contents and results of this paper are as follows: 1) A 5 blade single rotor small axial flow fan is used as the prototype. According to the blade angle modulation method, 13 kinds of unequal pitch fans with different maximum modulation angular displacement are designed, and 4 kinds of inlet guide vane fans with different inlet guide vane outlet angles are designed according to the design requirements of the imported guide vane. The numerical simulation method adopted in this paper is described briefly. 2) the results of numerical simulation show that: under rated working conditions. The maximum modulated angular displacement is equal to 6 掳with unequal pitch fan and the inlet guide vane fan with inlet guide vane outlet angle equal to 60 掳has the optimal noise reduction effect under the premise of satisfying the static characteristic requirement. Model 1 and model 2. Compared with the prototype, the static characteristics of model 1 remain basically unchanged. The results of model 2 show that the noise in the near field is mainly discrete noise, which is mainly caused by the total pressure pulsation. Both model 1 and model 2 can reduce the near-field discrete noise of the prototype. The far-field noise is mainly wideband noise, which is related to the vorticity distribution and vorticity variation of the flow field. Two single-rotor blade structures have little effect on the far-field wide-band noise of the prototype. The experimental results of model 1 and model 2 show that the numerical simulation is reliable, and the static characteristics of the prototype are not changed obviously when the maximum modulated angular displacement is 6 掳. The inlet guide vane with an outlet angle of 60 掳increases the static pressure of the prototype under rated working condition by 1.8 Pa. 5) and completes the prototype in the semi-anechoic chamber. The experimental results show that the maximum noise reduction of model 1 and model 2 in the downstream axial direction of the fan is located at the test point 100mm from the fan compared with the prototype. The noise reduction is 1.5 dB and 1.2 dB respectively; For the axial test point whose distance fan is greater than 400mm, the noise of the optimized model is basically consistent with the prototype. Reasonable selection of the unequal pitch distribution of a single rotor small axial flow fan blade can reduce the discrete noise in the near field on the premise that the static characteristics remain basically unchanged. The installation of inlet guide vane with suitable outlet angle can not only obviously improve the static characteristics of a small axial flow fan with a single rotor, but also reduce the discrete noise in the near field. In order to improve the internal flow characteristics, this paper will provide the basis for the optimization of the single rotor blade structure of Gao Jing low noise small axial flow fan.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH432.1;TB53

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