Compared with smooth tube

inner rib tube can greatly affect the fluid flow state in the tube. By changing the structure of upstream surface of the fin

different degrees of flow diversion effect will be produced. Conventional researches on fin structure are mostly regular figures

and the diversion angle is always consistent. In this paper

the effects of the structure of the upstream surface of the inner rib on the flow characteristics

heat transfer characteristics and comprehensive performance of the fluid in a circular tube are studied by numerical simulation. Five kinds of tube models are established with different concave convex structures on the upstream surface of the inner rib

and the effects of the five fluid models on the fluid are analyzed and compared

and their laws are discussed. The results show that

there is a strong correlation between the overall heat transfer performance and the convexity of the upstream surface. The sunken of the upstream surface of the inner rib can enhance the heat transfer of the heat exchange pipe

and the protruding of the upstream surface of the inner rib will weaken the heat transfer of the heat exchange pipe. At the same time

the resistance coefficient of the concave tube is higher than that of convex tube

and the comprehensive performance of the convex structure is slightly higher than that of the concave structure.