| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 102 === The main purpose of this study was to investigate the effects on the performance of a small axial flow fan, when concept of the high-lift devices was applied to its blades. A commercial fan RD1232 was used as a benchmark. In this study, pressure distribution on the blade surface was first evaluated in order to determine the proper locations for the addition of slot. Slot length, exit width and exit location were then chosen as the control parameters, and Taguchi method was applied for the design optimization process. At last, the best and worst design combinations obtained from Taguchi method were used for simulation under different pressure conditions to establish fan’s performance curve. Their flow field characteristics and performance data were also compared with the baseline fan in order to observe the effects of slot opening on the flow field. According to the Taguchi method, the final optimized design combination is with a full slot length(3/3), 1mm exit width, and exit located at 5/8 chord length. Based on the results from simulations, it shows that at low pressure, the addition of slot indeed help to increase the velocity on blade’s upper surface near the trailing edge. And it also augments the area of the negative pressure region upstream, which will help to attract more airflow and improve the airflow rate. However, under higher pressure, the slot becomes ineffective, and even begins to deteriorate fan’s performance. This implies that the blade combined with the concept of high-lift devices doesn’t work well as expected on situations with extremely high angle of attack. On the contrary, it does best when blades are facing mild stall. Nevertheless, fan with slotted blades can effectively reduced the torque under all the operating pressure, which can in turn cut the power consumption.
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