No matter from the theoretical or experimental point of view are fully proved, the jet wake structure of centrifugal fan impeller will become stronger with the decrease of flow rate. When the discharge is small, the wake is at the suction surface. When the flow is designed, the wake is at the intersection of suction and wheel caps. If you want to improve the efficiency of centrifugal fan, it is recommended to use blade slot Technology.
The specific method is to split the blade between the wheel cover and the blade of the centrifugal fan, so that the high pressure gas on the pressure side of the blade can be used to blow off the low velocity wake area at the suction side, and the energy is supplied directly to the low-speed fluid in the impeller.
The result of this design is that under the condition of design flow and small flow, the surface separation area of centrifugal fan impeller is reduced, and the speed of the whole impeller and the relative velocity distribution inside the impeller are more uniform, and the maximum absolute speed decreases obviously. The flow field in the impeller of centrifugal fan is more ideal, which can make the performance of centrifugal fan impeller and the performance of the whole machine reach a better level.
Not only that, the jet formed by the slit design can blow off the ash deposition on the suction surface of the centrifugal fan blade, which is beneficial to the impeller in the gas solid two phase flow. At the same time, we can also open the hole near the suction surface of the blade on the centrifugal fan wheel cover, and use the high-pressure gas generated in the volute to generate the jet, which directly provides the energy to the low-speed or separation fluid in the impeller, and helps to prevent the ash accumulation in the impeller.
Through numerical test of centrifugal fan with the discovery of its round head, in the fan near the design pressure and efficiency have been significantly improved. Especially in the design flow and small flow, the formation of a round opening due to the jet may improve the performance of the centrifugal impeller.