Effect of wall roughness by the bionic structure of dragonfly wing on microfluid flow and heat transfer characteristics

Abstract

In order to strengthen flow and heat transfer performance of the smooth rectangular microchannel (SRM), a novel of bionic rectangular microchannel (BRM) with a hydraulic diameter of 1000 um was designed based on the bionic wall roughness(BWR) of dragonfly wings structure. The effect of BWR and different microchannel lengths, and BWR with different tiny structures on flow and heat transfer was investigated, and the optimal of BWR's parameter, arrangement, combination and Re number range were studied. The results indicated that the influence of BWR on the flow and heat transfer performance is significantly better than that of SRM. When the Re is 5830, the heat transfer performance of the BRM model is 2.08 times that of SRM, and the heat enhancement factor is 1.233. Moreover, the optimal BRM's maximum velocity of the fluid is 19.6 m/s, which is 3.1 times of that of SRM, and the maximum temperature is 14.3 K lower than that of SRM, and an enhancement of 218% in heat transfer was achieved compared to a SRM, and the thermal enhancement factor is 1.34. Compared with BWR effect, the influence of the entry effect on heat transfer can be ignored, and the existence of BWR increases the number and scope of fluid disturbance and brings a large number and a wide range of high speed vortex flow appears in BRM, and they are regularly distributed after each group of BWR and the central of the microchannel, which further increases the flow velocity and disturbance, and reduces the range of low-speed and high-temperature region near the wall, and finally enhances flow and heat transfer performance.