Simulation study on the time-invariant air-flow characterization of centrifugal fan

Flow-field characterization of centrifugal fan should be time-invariant when the air entered into the core of propeller and then outflowed from discharged duct. In the process, a strong transient fluid-solid coupling phenomena between multi-parts and their surrounding stochastic air maybe occurred. The strong fluid-solid coupling could be harmful to the service life and acoustic performance of centrifugal fan. So, Study on the flow-field information was great important. In this paper, detached eddy simulation (DES) was adopted to explore the air moving mechanism of a centrifugal fan. The calculation results showed that at the leading edge of blades and the gap between the impeller rear plate and the casing wall, the airflow vortices would be occurred firstly when the propeller started to be in motion. Subsequently, a great quantity of flow phenomena occurred in the whole region of propeller, such as flow distortions, eddies and airflow separation. Meanwhile, the large velocity and pressure difference occurred at two regions. The one region was from the gap between the casing and inlet guide ring, the other region was located in the clearance between vortex tongue and trailing edge of propeller. An interesting flow phenomena was found that the moving air from propeller to vortex tongue turned flow direction, namely, the air moving direction was from shroud to impeller rear plate at a fixed angle. By means of modifying the relevant configuration parameter to alter the aforesaid airflow characterization, the acoustic and structural performance of centrifugal fan could be improved effectively.