||The purpose of this study is to propose and verify a design process for the impellers of an axial-flow fan to meet the heat dissipation requirements of a condenser system. A finite element analysis (FEM) technique is applied to determining the flow field and performing the structural analysis with a fluid-solid coupling method. The natural frequency is determined to make sure that resonance is not going to take place in operation of such a fan.|
The key specifications for such an axial-flow fan include an air flow of 8580 m3/h and a wind pressure of 50 Pa. Through fluid dynamics analysis with FEA, a proper set of setting angle and airfoil is selected for the impeller geometry to meet the requirements at a fan speed of 950 rpm among five initial designs considered. A fabrication process using sheet metal, for reducing cost, is further considered in making the final design of the impellers. The final design of the sheet metal impellers is verified to meet the requirements in fluid mechanics by FEA simulation. Subsequently, a fluid-solid coupling FEA simulation is conducted to assess the structural integrity of the impeller design at a higher fan speed of 1050 rpm. As no structural failure is predicted by the simulation according to the von Mises criterion, a mockup of the impeller design is fabricated for testing. Experiments such as wind tunnel test, strain measurement for hub platform, and natural frequency measurement are then conducted on the mockup sample to evaluate its performance and stability and to verify the simulations.
Experiments and simulations, based on the specification of MACA 210-07, both verify that the sheet metal impellers designed in this study can meet the heat dissipation requirements of a condenser system. A good structural integrity is expected, as the safety factor for the components hub of platform, blade, washer, and bolt is 2.57, 2.14, 4.81, and 1.78, respectively. The natural frequency of the first modal vibration is 24.6 Hz which is higher than the maximum working fan speed of 1050 rpm (17.5 Hz). Accordingly, no resonance is expected to take place.
||1. 林偉凱,冷凍空調工程技術知識概況分析,財團法人金屬工業研究發展中心, 2005.|
2. 一丞冷凍工業股份有限公司,技術手冊, 2014.
3. 德國弗格森中國公司網站, 取自
http://www.focusun.com.cn/blog/38, accessed on November 9, 2009.
http://www.karos.com.tw/index_down7b39.html?openCatIDfor3=4&openCatID=9&CAhs=&ISPID=19&IIBig=9&sele=shopbig_dm_right, accessed on February 3, 2013
5. 浙江奥星制冷設備有限公司產品目錄,取自http://www.zjaxzl.com/Product/978520431.html, accessed on July 16, 2014.
6. 洪國泰, “小型軸流風扇之設計、模擬與實驗整合研究,” 台灣科技大學機械工程研究所碩士論文, 2007.
7. 藍重凱, “軸流風扇翼型與角度對性能曲線的影響,” 清華大學工程與系統科學研究所碩士論文, 2004.
8. 林重安, “軸流式風扇之流場模擬與實驗,” 台灣科技大學機械工程研究所碩士論文, 2007.
9. J. Hurault, S. Kouidri, F. Bakir, and R. Rey, “Experimental and Numerical Study of the Sweep Effect on Three-Dimensional Flow Downstream of Axial Flow Fans,” Flow Measurement and Instrumentation, Vol. 21, pp. 156-165, 2010.
10. 蔡明倫, “風扇性能評估與設計方法之整合研究,” 台灣科技大學機械工程研究所博士論文, 2010.
11. 邱博異, “軸流風機於 AMCA 風洞測試性能預測比較分析,” 雲林科技大學機械工程研究所碩士論文, 2011.
12. X. Zhao, J. Sun, and Z. Zhang, “Predition and Measurement of Axial Flow Fan Aerodynamic and Aeroacoustic Performance in a Split-type Air-conditioner Outdoor Unit,” International Journal of Refrigeraton, Vol. 36, pp. 1098-1108, 2013.
13. 陳浩民, “軸流式風扇流場及振動之分析和最佳設計,” 崑山科技大學機械工程研究所碩士論文, 2004.
14. 楊景富, “泵浦流場及振動之分析和最佳設計,” 崑山科技大學機械工程研究所碩士論文, 2004.
15. 黃啟忠, “汽輪機低壓葉片流固耦合數值分析,” 高雄應用科技大學機械與精密工程研究所碩士論文, 2008.
16. Q. Wu, Y. Zhang, and H. Azhang, “Dynamic Characteristic Analysis and Experiment for Integral Impeller Based on Cyclic Symmetry Analysis Method,” Chinese Journal of Aeronautics,Vol. 25, pp. 804-810, 2012.
17. E. N. Jacobs, K. E. Ward, and R. M. Pinkerton, “The Characteristic of 78 Related Airfoil Sections from Tests in the Variable-Density Wind Tunnel, ” NACA Report No. 460, National Advisory Committee for Aeronautics, Langley Memorial Aeronautical Laboratory, Virginia, USA, 1933.
18. E. N. Jacobs and R. M. Pinkerton, “Test in the Variable-Density Wind Tunnel of Related Airfoils Having the Maximum Camber Unusually Far Forward,” NACA Report No. 537, National Advisory Committee for Aeronautics, Langley Memorial Aeronautical Laboratory, Virginia, USA , 1936.
19. Technical Resources, BOSSARD Co., Ltd., 取自
http://www.bossard.com/zh/application-engineering/technical-resources/preload-and-tightening-torques.aspx/T_Teil_044_054_SCN%20(2).pdf, accessed on September 19, 2014
20. ASNI/AMCA Standard 210-07 (ANSI/ASHRAE51-07), “Laboratory Method of Testing Fans for Aerodynamic Performance Rating,” Air Movement and Control Association, Illinois, USA, 2007
21. 台灣瑞領科技有限公司網站, 取自
http://www.longwin.com/download/presentation/AMCA-210-07-WT-Introduction-OP-App-20131024.pdf, accessed on July 1, 2014