对旋式轴流风机优化设计及变转速匹配性能研究

发布时间：2018-12-12 08:24

【摘要】：本文首先综述了国内外对旋式轴流风机的现状、发展趋势和存在的问题,分析了其空气动力性能和结构特征。在此基础上,保证设计点两级等负载分配,通过对轮毂比、弦长比、变环量流型等参数对性能影响的对比研究,设计得到一高效双级对旋式轴流风机。进一步,对该对旋式轴流风机的变转速匹配特性进行了数值模拟研究。本文主要工作及结果如下： 1.采用等环量设计方法,在设计流量点,首先讨论了轮毂比对风机性能的影响,优选得到适当的轮毂比参数；然后,通过改变叶片弦长沿叶高的变化规律,研究了稠度变化在调节两级叶轮负荷分配中发挥的作用,初步优选得到了高压比、高效率对旋式轴流风机的设计方案；最后,针对在设计工况的优化方案,研究了其在全流量范围的变工况性能。 2.为进一步提高对旋式轴流风机设计性能,在采用等环量设计方法优选得到的高压比、高效率风机设计方案基础上,在保证设计点两级等负载分配前提下,采用变环量流型设计方法,分别对比研究了两级转子不同展向载荷分配规律对对旋式轴流风机性能的影响,从中确定了性能最佳的两级转子径向载荷分布规律,并给出了近似描述该变化规律的数学表达式。 3.采用全圆周数值模拟方法,对包括进口集流器、两级转子和出口扩散器的双级对旋式轴流风机整机进行了变转速匹配特性研究。在四种转速匹配方案下,对比分析了风机整机和各级转子的压升、效率和功率特性,进一步深入流场内部,揭示了不同转速匹配下的内部流动特征,并与仅包含两级转子的单通道模拟结果做了对比。对单级转子特性而言,单通道模型和全圆周模型间最大的区别在第二级转子,就全压升和效率来说,单通道模拟结果高于全圆周模拟结果。不同转速匹配下的结果均显示,第二级转子性能改变对转速变化更为敏感。除各级转子的良好设计,进口集流器和出口扩散器对提高对旋式轴流风机的性能也很重要。
[Abstract]:In this paper, the present situation, development trend and existing problems of counterrotating axial fan are reviewed, and its aerodynamic performance and structural characteristics are analyzed. On the basis of this, the design point and two stages of equal load distribution are guaranteed. Through the comparative study of the influence of wheel hub ratio, chord length ratio and flow pattern of variable ring volume on the performance, an efficient two-stage counter-rotating axial flow fan is designed. Furthermore, the variable speed matching characteristics of the counter rotating axial fan are numerically simulated. The main work and results are as follows: 1. At the design flow point, the influence of wheel hub ratio on fan performance is discussed by using equal ring design method, and appropriate hub ratio parameters are obtained. Then, by changing the variation rule of blade chord length along the blade height, the effect of consistency change in regulating the load distribution of two stage impeller is studied, and the design scheme of high pressure ratio and high efficiency counter-rotating axial fan is obtained. Finally, according to the optimization scheme in the design condition, the off-condition performance in the whole flow range is studied. 2. In order to further improve the design performance of the counterrotating axial fan, on the basis of the optimum selection of high pressure ratio and high efficiency fan design scheme by using the equal ring quantity design method, under the premise of guaranteeing the two-stage equal load distribution at the design point, In this paper, the influence of different spanking load distribution law of two stage rotor on the performance of rotating axial fan is studied by using variable annular flow pattern design method, and the radial load distribution law of two stage rotor with the best performance is determined. A mathematical expression describing the variation law is given. 3. The variable speed matching characteristics of a two-stage counter-rotating axial fan including an inlet collector, a two-stage rotor and an outlet diffuser are studied by using the full-circle numerical simulation method. Under four kinds of speed matching schemes, the pressure rise, efficiency and power characteristics of the whole fan machine and the rotor at all levels are compared and analyzed, and the internal flow characteristics under different speed matching conditions are revealed. The results are compared with the single channel simulation results with only two stage rotors. For the characteristics of single-stage rotor, the biggest difference between single-channel model and full-circumferential model is in the second-stage rotor. In terms of full pressure rise and efficiency, single-channel simulation results are higher than that of full-circumferential simulation. The results of different speed matching show that the performance change of the second stage rotor is more sensitive to the speed change. In addition to the good design of the rotor at all levels, the inlet collector and the outlet diffuser are also important for improving the performance of the counterrotating axial fan.
【学位授予单位】：中国科学院研究生院（工程热物理研究所）
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH432.1

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