The centrifugal fan with straight front panel is favored by more and more fan manufacturers for its advantages of simple manufacturing and processing,quick replacement of worn blades,etc.The straight front panel is flat and straight at the front panel from the blade inlet to the outlet,and only the front panel near the collector adopts appropriate arc transition,which not only ensures the convenient processing of the straight front panel,but also has good diversion effect.However,compared to fans that use general curved or conical front panel,the problem that needs to be solved is the low efficiency of the fan after using a straight front panel.Based on SST turbulence model,this paper conducts numerical simulation on a straight front panel centrifugal fan,analyzes the internal flow field and its existing problems,optimizes the design and analysis by changing the structure of blade passage and volute tongue,improves the operation efficiency of the straight front panel centrifugal fan,expands the range of efficient operation area,and maintains its pressure within a reasonable range,And aerodynamic performance tests were conducted on the prototype of the final optimized fan to verify the reliability of the optimization results.The main research content is as follows:(1)The original design parameters of the straight front panel centrifugal fan are summarized,the aerodynamic three-dimensional model of the original fan is established,and the appropriate numerical simulation method is selected and the corresponding calculation conditions are set according to its characteristics.Based on the aerodynamic performance parameters obtained from the calculation and the internal flow field information,the analysis is carried out,and it is found that there is a large boundary layer separation in the internal flow field,and there are problems such as "jet wake" structure,The structural deficiencies of the original straight front panel fan model were pointed out.(2)The volute tongue structure has been adjusted and a preliminary optimization plan for the impeller flow channel has been proposed.First,modify the form of the volute tongue,changing the pointed tongue to a shallow tongue,which means increasing the distance and curvature of the volute tongue appropriately to reduce the high-speed airflow impact at the impeller outlet and reduce pressure pulsation.Further preliminary optimization was carried out on the impeller flow channel.By adjusting the blade profile,the inlet diameter of the blade was increased,resulting in a significant improvement in the flow situation in the impeller flow channel and an increase in fan efficiency.The necessity of performing oblique cutting on the blade after increasing the inlet diameter of the blade was discussed,and it was found that further oblique cutting on the inlet end of the blade would have adverse effects on the aerodynamic performance of the fan.The influence of different blade height schemes on the aerodynamic performance of a straight front panel fan was compared,and the optimal blade height scheme was determined.(3)On the basis of the preliminary optimization of the straight front plate centrifugal fan,the influence of the number of blades,the scheme of adding splitter blades and the blade outlet angle on the aerodynamic performance of the fan was studied.The results indicate that adjusting the number of blades appropriately and reducing the blade outlet angle can help further improve the internal flow field of the straight front panel fan,weaken the flow separation phenomenon in the impeller channel,and improve operating efficiency.However,adding splitter blades has a limited effect on the efficiency of the flat plate fan,but it was found that adding splitter blades of different radial lengths will have different effects on the fan efficiency.The final blade structure parameter scheme was selected,and the results showed that the high-efficiency operating zone of the optimized fan was significantly widened,with a maximum efficiency increase of 5.5%.The error between the numerical calculation value and the measured value of the air duct test was 2.3%,and the calculated value was basically consistent with the measured value. |