| In the heating system,the connection between the pipe and the end heat sink is usually realized by changing the diameter at the end of the heating system.The existence of changing the diameter causes the increase of resistance and energy consumption.In this paper,by optimizing the connection structure between the end device and the pipeline,the energy consumption and the end resistance of the pipeline are reduced when the diameter of the pipeline is changed.This paper will provide guidance for the scientific and rational design of end device connection structure.When the fluid flows along the streamline structure,the local resistance loss is small,so how to design the streamline variable diameter structure rationally and reduce the resistance loss of the end device connection structure is the key of this paper.In this paper,a method to reduce local resistance loss is proposed by analyzing the energy conversion process of fluid passing through variable diameter.Based on the differential equation of fluid motion,a physical model of drag reduction with variable diameter is established,and the structure of drag reduction with variable diameter is optimized.An experimental platform for resistance measurement of the optimized tube with variable diameter is built.The theoretical and Experimental Research on the proposed drag reduction method and the optimized drag reduction structure is carried out.The results show that the drag reduction method obtained by theoretical research and the optimized drag reduction structure have better drag reduction effect.When the Reynolds number Re is between 4000 < Re < 1000,the drag reduction effect of the drag reduction structure is better than that of the traditional tapered structure.Compared with the tapered structure,the average drag reduction efficiency is 59.2%,and the maximum drag reduction rate is 87.7%,which is better than that of the tapered structure.Compared with the diameter structure,the average drag reduction efficiency is 22.1%,and the maximum drag reduction rate is 76.5%.The optimized variable diameter drag reduction structure can effectively reduce the fluid resistance loss and save energy. |
