Optimization Design Study Of Variable Circulation Axial Flow Fan

Fan is one of the turbo machinery widely used in social production departments.Electric power resources are consume on fans as a percentage of the total electricity consumption is high every year. However, the working efficiency of the fan in our country is generally low in the actual operation, thus caused the waste of energy sources is very considerable. So, it is very important to improve the level of design and manufacturing of fan and the fan efficiency it will has a very positive significance to the development of national economy, energy saving and environmental protection.On the basis of previous laboratory studies, in order to solve the problems of small axial flow fan such as large pressure coefficient, more relative loss and so on, a variable circulation flow pattern that its circular rectors change linearly along the radial direction had been proposed in this paper. This paper completed the design and calculation of 75 impellers which are orthogonal by five hub-shroud ratios and 15 group circulation ratios use the variable circulation flow pattern. According to the design and calculation results, creating 3d modeling of each impeller by Creo2.0software. Then, using the ICEM and Fluent module of the ANSYS software respectively to create mesh and finish simulation calculation of each impeller. Finally,comparing the performance of each impeller by the simulation calculation results, we can optimize the hub-shroud ratios of impellers in the given range and seek the rule between the highest efficiency of the impellers with different hub-shroud ratio and the variable circulation ratio related to the variable circulation flow pattern.In addition, this paper finished the comparison and analysis of equal circulation flow and variable circulation flow. The main conclusions of numerical simulation as follows:(1)When variable circulation ratio is in the range of 1.1 to 1.3,the highest efficiency value of variable circulation axial flow fan is generally larger;(2) The highest efficiency value of fan impeller was increased firstly then decreased with increasing of variable circulation ratio with different hub-shroud ratio.And there was an optimum variable circulation ratio which can make the highest efficiency value maximum;(3) The highest efficiency value and high efficiency range of the fan which designed by the variable circulation flow pattern were larger than the ones designed by equal circulation flow pattern with the optimal variable circulation ratio. And thefan designed by variable circulation flow pattern,could not only reduced the distortion of the blade, but also improve the work environment of leaf blade root effectively.At last, this paper focused on the fan impeller whose highest efficiency value was maximum in the 75 impellers of simulation calculation. Schematic of impeller,manufacturing diagram of die and cutting diagram of blade were drawn and physical model of blade die was manufactured by self. The impeller was processed and manufactured finally. This paper also made a performance experiment of the impeller,and the main conclusions of performance experiment as follows:(1) With the increase of air flow, total pressure efficiency of the impeller showed a trend of increased firstly then decreased and total pressure decreased gradually, total pressure curves showed approximate saddle shape in conformity with the theory;(2)The highest efficiency value of the impeller which was processed in the paper larger than the impeller which had a relatively good performance of five original impellers in the laboratory. But when airflow was greater than the design airflow, the rate of change of the former's total pressure along with the change of air flow was much faster, and the slope of the total pressure curve was larger.