Numerical study on performance improvement when strong vortex occurs on the shroud of vaneless diffuser in turbo blower

摘要

This research is about improving the performance of a turbo blower when a strong vortex occurs on the shroud of a vaneless diffuser. The design parameters for a vaneless diffuser in a turbo blower were analyzed, and the optimum design conditions for a vaneless diffuser were derived. Among these parameters, the independent ones were outer radius of the diffuser (R-d), cross-sectional area ratio of the diffuser (A(d)/A(i)), and generation method for the shroud curve in the diffuser. The dependent parameter was fan static efficiency in the CFD; moreover, the purpose of this study was to maximize this efficiency. The influence of the design parameters was analyzed using Computational fluid dynamics (CFD) and Design of experiments (DOE). The reliability of CFD results was verified by comparing the experimental and CFD results obtained using a preliminary model. For DOE, a full factorial design and the response surface methodology were employed, and a regression equation was used for deriving the optimum design conditions. The DOE results revealed that as Rd increased and A(d)/A(i) increased accordingly, the fan static efficiency in the CFD also increased. Furthermore, as R-d increased, the high-value range of the fan static efficiency in the CFD increased. In general, the performance of the turbo blower was enhanced when the vortex region in the vaneless diffuser decreased in area. In addition, the cross-sectional area of the vaneless diffuser was designed to achieve recovery of static pressure.