Optimization Of Multi-blade Fan And Internal Flow Field Of Range Hood Case

With the increasing of kitchen range hood penetration rate in China, the performance requirements of the air volume and noise is becoming higher. In order to improve the market competitiveness and the user’s experience, it is great significant for the range hood products to optimize the aerodynamic performance and noise.This thesis comes from a school-enterprise cooperation project, whose optimization goal is the maximum air volume over 16m3/min.The main work of this thesis is to reach the target of the air volume at low speeds by optimizing the range hood aerodynamic performance.On the basis of existing engineering experience and product research, some measures are applied, such as improving the installation angle, diameter, height of blade and other structural parameters of forward multi-blade fan impeller, single inlet forms changed to double inlet forms, matching the volute and collector gear, to improve the aerodynamic performance of the multi-blade fan. As the goal of flow volume and efficiency, the three-dimensional modeling and numerical simulation of multiple improvement programs are carried out to find out the best model program. Simultaneously, their internal flow field is compared and analyzed.On this basis, guide plate is set on the collector gear side of the hood body wall to improve the gas flowing within the body. To determine the best form of guiding plate and further improve the performance of the range hood, a variety of guide plate model are designed and the numerical calculation results are compared. At the same time, different length of air outlet is modeled and the influence of its length on the performance of range hood is analyzed by numerical simulation.After the improvement of the multi-blade fan and the internal flow field of the hood body, the maximum air volume of newly designed range hood reaches 20m3/min. Compared with the original range hood, the air volume is increased by 24%.