The Numerical Simulation And Optimization Design Of High Efficiency And Low Noise Centrifugal Fan

The centrifugal fan is a common kind of turbo machinery. It is widely used in drainage project because of its small volume and high pressure coefficient. The inner-flow field in the centrifugal fan is numerically simulated and its flow characteristics are analyzed by numerical method in the paper.Firstly,the three-dimensional model of the centrifugal fan was established. The impeller was set as moving regions. The inlet and volute were set as stationary regions. The model was meshed by non-uniform tetrahedral meshes. The partial differential equation was discrete by finite volume. Based on the three-dimensional time averaged N ? S equation and the k ?εturbulent model, the SIMPLE algorithm were selected in order to numerically simulate the inner-flow field in the centrifugal fan. Two strong turbulence and high noise regions: the inlet of the impeller and the volute tongue, were found by analyzing the inner-flow field. Meanwhile, the result showed many important phenomena of the inner-flow in the centrifugal fan,such as the second flow in the blade channels, the''jet-wake''phenomenon at the exit of the blades and the vortex flow in the volute.Secondly, the strong turbulence region, the inlet of the impeller and the volute tongue were mainly analyzed and researched. That the inlet matched the impeller was the main factor inflecting the flow velocity distribution and vortex flow at the blade inlet. The key parameter of shape of the inlet was the opening angle. The relationship model between opening angle and the flow velocity at the blade inlet was established in the paper. The best opening angle matching with the fan was 14 ? by comparing the variance of the flow velocity at the blade inlet under different opening angles. The relative clearance at the volute tongue was the main reason of the tone noise of the fan. The noise contours in the different relative clearance were compared and analyzed in the paper. The optimal relative clearance was determined as 12 %。 A centrifugal fan was designed and manufactured according to the numerical simulation results. The experiments of the performance and noise on the fan were conducted. The simulated result was testified to be reliable. Meanwhile, the test results indicated the excellent performance and low-noise of the centrifugal fan.