Study On Characteristics And Internal Flow Of Flap Adjusted Centrifugal Fan Based On Splitter Blades

Centrifugal fans are widely used in various industries, but the overall efficiency is low. For this situation, splitter blades technique and flap adjustment are proposed for G4-73-11№.5D centrifugal fan. Research tools include SolidWorks, GAMBIT and Fluent etc. Grid-independent inspection and numerical simulation credibility are carried out,as a result, the numerical simulation is correct and credible.And the conclusions are as follows:(1) The characteristic curves of different lengths, different circumferential position and different blade types are carried out. From the results, the short blades are optimized. So the best length is 25% of the long blade, the best circumferential position is 1/6 of the flow path near the pressure surface, and the best type is arc board.(2) Simulation of flap adjusting centrifugal fan based on the best shot blade is finished. From the simulation, characteristic curves are finded. To compare it with the original fan, maximum efficiency is 87.3% which is 2.1% higher than the original one, and the pressure is 822 Pa which is 1% higher. When compare it with flap adjusting fan without short blades, the efficient workspace expands, and the ability to work improves, the pressure curve becomes flat, the low flow condition improve. So the desired goals are achieved.(3) When the angle changes, total pressure curve changes a lot. When the angle is negative, the change is more obvious, the adjustment range is wide too. So the flap adjustment is sensitive, applicable and economic.(4) After adding the best short blades, there is no separation in the optimum conditions, and there is an obvious separation in the optimum conditions of non-short blades, which can be considered that short blades suppress the separation, in a word, short blades is optimal. Adjusting the rotor blades, in the regions of the short blades and up and down, there is no flow separation or less, which improves the internal flow effectively, reduces the flow losses and raises the efficiency. Meanwhile, bucket angle increases, the full differential pressure of import and export increases, increases the pressure of the fans working.(5) The adjusting Centrifugal Impeller of long and short variable blades exists "jet-wake" phenomenon. After joining the best short blades, the "jet-wake" phenomenon is improved, reducing the flow losses and increasing the efficiency.(6) After adding the short blades, both of the impeller outlet velocity and pressure pulsation reduce, each flow path has uniform flow, and vorticity distribution improved a lot. So that the overall performance of fans increased.In summary, flap adjusting centrifugal fan based on splitter blades is feasible which has high efficiency, wide efficient area, wide adjusted range, stable flow in low flow and high total pressure. As a result, there is high research value of this type of fan.