The Study Of Optimal Design System For Centrifugal Fan Based On Velocity Distribution Control

As an important general mechanical equipment,centrifugal fan consumes a lot of energy,so it is very necessary to establish the optimal design system of centrifugal fan for high efficiency performance.Based on the optimal design method of the centrifugal impeller which controls the velocity distribution,a new design method of the meridional surface forming and volute is established in this paper,then combined with blade shape optimal design the optimal design system of the centrifugal is developed.The optimal design system is programmed with C language,and used in practice.This optimization design system innovatively realizes the organic combination of the general structural parameter,meridian surface forming and blade forming optimization,and the volute design includes the viscous effect,thus this optimization design system is a new method.First of all,according to the internal flow characteristic of centrifugal fan,the reasonable optimization criteria are adopted,that is,the optimization criteria of inlet width,inlet / outlet diameter ratio,inlet angle,and the equivalent expansion angle.Secondly,a forming method of the front disc with Bezier function,which is efficient and convenient in the forming process,is set up.During the front disc forming,the shape optimization is combined with the optimal criteria of impeller inlet diameter and blade inlet angle,so that the relationship between general structural parameter optimization and front disc shape optimization are organically integrated.Thirdly,in order to make the optimization process more reasonable,the relationship between the equivalent expansion angle criteria and the blade shape optimization is established.Finally,the continuity equation and the angular momentum equation are used to design volute considering the influence of viscosity,which makes the volute design more practical and efficient.The optimization design system of centrifugal fan established in this paper is applied to the optimization design.The flow field status of the rotating surface and meridian surface,the influence of different velocity distribution,and the performance changes of the volute before and after the optimization design are comparatively analyzed.The results show that the accumulation of low energy mass at the suction side of blade outlet after optimization is reduced,the jet wake structure is weakened,and the vortex flow on the meridian surface is reduced,the secondary flow is restrained.Different average velocity distribution of blade channel will affect the loading mode and the change rate of blade angle.The larger the change rate of blade angle at the outlet,the more the flow tends to separate.The flow loss of the volute is reduced and the efficiency is improved by using the volute design considering viscosity.In summary,with the optimization design system established in this paper,the meridional flow status is improved,the secondary flow is restrained,the expansion effect is better,the flow separation is restrained,the fan efficiency and pressure coefficient after optimization under all working conditions are obviously improved,these show that the optimization design method is reliable.