| Summary: | 碩士 === 國立雲林科技大學 === 機械工程系 === 107 === The research object of this thesis is the Fan Filter Unit(FFU) used in the clean room, and it is different from the design of the common centrifugal fan that is covered inside a volute casing. The centrifugal impeller in this study is installed in a rectangular parallelepiped box. In this study, without changing the design and size of the impeller itself, change on the design of the volute and the supporting bottom plate in the box will be carried out, and hope to improve the efficiency of the FFU.
In the study, the model was first drawn using SolidWorks, and then imported into the ANSYS-CFX software for simulation. Design changes include two parts: the double volute and the four volute. In addition to first evaluating the necessity of the existence of the volute, the double volute part will also discuss the volute designed according to the different spiral curve formula, and the effects of ratio of the vertical distance (S) between the volute and the impeller and the impeller radius (R) on the performance of the fan. As for the four volute parts, the four different volute designs of A, B, C, and D, and the influence of the S/R ratio are discussed, and the two best performers are selected, and the effect of adding flow guiding devices to the supporting bottom plate is further evaluated.
According to the research results, after the volute is removed, due to the lack of proper guiding mechanism, the airflow distribution inside the casing is messy, so the demanding torque is greatly increased, which proves that the volute has its necessity. Among the original volute, volute 1 and volute 2, the volute 1 designed according to the theory of free vortex is the best; and regardless of the design, the S/R ratio for the best performance is around 0.9. As for the part of the four volute, the four volute C-S/R=1.2 and the four volute D-S/R=0.9 performed best, and the overall efficiency increased by 4.74% and 4.2%, respectively, compared with the original model. However, the best performing S/R ratio does not have a fixed value as in the double volute model. If the two optimal designs are respectively installed with three different flow guiding devices, the airflow in the four volute C is better guided by the flow guiding device, and the efficiency is further improved by 6.1% compared with the original model; but the four volute D’s performance is flat or worse. In summary, the model of the four volute C-S/ R = 1.2 with the guiding device can maintain a certain degree of performance improvement after the volume flow rate is increased over 30 CMM.
|
|---|
