| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 105 === The object of this research is a ventilation device commonly used in the clean room of semiconductor process, and its main component is a centrifugal fan arranged in the center of the cabinet. It is hoped that without changing the design and size of the centrifugal fan , the device’s performance can be improved simply by modifying the surrounding structures inside the cabinet. In this study, ANSYS CFX was used to analyze the flow field. At first, simulations were carried out on the removal of angle iron, volute and supporting plate in order to observe the effects of these existing accessories. Followed by separate evaluations of performance impact of using the round hood originated from Coanda effect to replace all the accessories, the change of volute design, installation of a diversion cone at the center of air intake area of the impeller, and the change of cabinet’s height.
Based on the research results, it shows that in the gradual removal of various parts inside the cabinet, the impact on the output volume flow rate is very limited, but the efficiency can be significantly increased, and so is the distribution of the air outflow. Therefore, the existing accessories can be removed unless needed. When all the accessories were replaced by a round hood, it was found that the Coanda effect was effective indeed. Although the performance did not get better, but kept close, and the noticeable difference is the distribution of outflow air. In the optimization of the round hood¸ it is found that the horizontal position of the arc is more important than the vertical position. The same concept had also be proved that can be applied to the edges of the supporting plate to replace the diversion angle iron and maintain the same level of performance with difference outflow distribution. Results also show that the performance of the modified volute curve based on theoretical and empirical formula is competitive, which means the design of the volute can be modified more systematically when facing a change of centrifugal fan in the future. Since the air flow at the impeller inlet area is already very smooth, so it has been proven that the installing of a diversion cone in the central area is not needed. As for the height of the cabinet, it is found that a height changes can alter the relative size of the internal space, and thus affect the air flow at the corner of the cabinet, which in turn will have a slight impact on the performance of the device.
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