The second part tells the related knowledge about grids of the Gambit 。 Mainly about the detailed introduction of how the grids are partited and the boundary conditions are set。 Meanwhile, here also involves the relevant knowledge to model initialization, the application of standard of k- Ɛ turbulence model and the Renault's average navier-stokes equations 。The Analyses of the rotating impeller to velocity distribution, the pressure distribution of fan and the internal flow pattern in this part are important。The third part tells a finite element model established for fan impeller。 By meshing the impeller model extract the fans modal parameters in ANSYS software。The last part contains the establish of the spiral's finite element model, and the model 's modal analysis and the dynamic response analysis。 With analysing the different thickness of the fan shell's vibration characteristics, and referencing the second part of the diffuser stress results, we can calculate the shell's vibration frequency distribution。

Through the above study found that similar design income fan volute inherent frequency is relatively concentrated, we can increase the thickness of the volute to improve it's structure characteristic。 Meanwhile, judging from harmonic response analysis results, so that also helps the axial displacement of the spiral of reduced。 Secondly, the isometric impeller large displacement is still to be further studied, we can use new materials to make the impeller in order to reduce displacement deformation。 Finally, although there still be some difference between the model and the actual fan ,but the noise reduced 15dB around after using the isometric leaves 。 Thus, indicating that this scheme is effective and feasible。

Keywords: Centrifugal fan; Unequal pitch blade; Vibration and noise; Finite element; Boundary element

目 录

第一章 绪论 1

1。1 引言 1

1。2 风机降噪的重要意义 1

1。3 国内外研究现状和发展前景 2

1。4 研究内容及研究方案 4

第二章 风机的相似设计及三维建模 5

2。1 通风机基础知识 5

2。2 离心式风机理论设计 6

2。2。1 离心式风机概述 6

2。2。2 离心式通风机设计方法 8

2．3 离心式风机的基本结构设计 10

2。3。1 风机的性能参数 10

2。3。2风机的设计 10

2。4 风机的三维建模 20

第三章 流场分析及噪声计算 25

3。1 流场网格的生成 25

3。2 风机流场边界条件 26

3。3 风机流场计算结果与分析 26

3。4 计算结果分析 28

3。4。1 分机流场速度分布 28

3。4。2 分机流场压力分布 30

3。4。3 新型风机与改进后的风机流场的对比 32

3。5 噪声计算 36

第四章 风机蜗壳与叶轮动力学分析 40

4。1 风机蜗壳的模态分析和谐响应分析 40