Abstract
This paper takes centrifugal fan as the research object and establishes five impeller models with different blade outlet angles. By means of computational fluid dynamics (CFD), the external characteristics of the centrifugal fan and the internal characteristics, including the velocity, pressure, and turbulent energy distribution, at the middle span plane of the impeller or fan were obtained and compared. In addition, the pressure fluctuations surrounding the impeller outlet were also analyzed. The results showed that the change of the blade outlet angle of the centrifugal fan had a great influence on the performance; the total pressure and efficiency of the fan were the highest when the outlet angle of the blade was increased to 29.5° under the design flow rate; and the influence of the outlet angle on the fan performance was different in off-design conditions. On the other hand, at different flow rates, the change of the internal flow field with the increase of the outlet angle was different. For the pressure fluctuation of the fan, by increasing the blade outlet angle properly under high flow conditions, the fluctuation amplitude of the fan at the blade frequency and its frequency multiplication could be reduced, which is conducive to decreasing the impeller noise. The research results have good guiding significance regarding the design of the pneumatic performance and noise reduction performance of centrifugal fans.
Highlights
Fans belong to the category of general machinery and are widely used in various industries of national economy
Q/Qdes is the ratio of the experimental flow rate to the design flow rate
The other factor was that the actual flow rate of the fan was transient, which is ignored by the frozen rotor method
Summary
Fans belong to the category of general machinery and are widely used in various industries of national economy. Meng et al [12] studied the influence of three blade structure parameters on the performance of a centrifugal fan, which were inlet angle, outlet angle, and blade number, and obtained that the best combination of the three blade structure parameters using the response surface model (RSM) optimization method. As the main parameter of impeller, the blade outlet angle of centrifugal fans has been studied by scholars. Swe et al [16] discussed the flow characteristics of centrifugal fans with different blade outlet angles using the CFD numerical simulation method. Through theperformance software post-processing, the influence of different outlet angles on internal flow field and of the centrifugal fan was studied.
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