Flow and heat transfer improvement in microfluidic thermal camouflage film by topology optimization

Abstract

Microfluidic thermal camouflage films conceal infrared targets by circulating liquid within the film, representing a novel approach to microfluidic camouflage technology. A topology optimization method applied to the design of bionic honeycomb structure is proposed to achieve the dual goals of enhancing heat transfer and reducing flow resistance. Firstly, a variable density topology optimization model of the bionic honeycomb structure is established, and the influence of model parameters on the optimization results and convergence is analyzed. A synergistically topology-optimized film, aimed at optimizing thermal uniformity and fluid flow energy consumption, is obtained. Subsequently, numerical studies indicate that the topology-optimized film surpasses the traditional honeycomb structure camouflage film in terms of temperature distribution uniformity and heat transfer performance. To validate the numerical simulation results, a prototype of the optimized honeycomb topology with the ideal morphology is fabricated, and its flow and heat transfer characteristics are experimentally studied. Finally, a thermal camouflage performance test system is constructed to explore the thermal-fluid coupling law and the enhanced heat transfer mechanism of the topology-optimized honeycomb structure. Specifically, the TO film reduced the maximum temperature difference by 28.94 % compared to the traditional film at Re = 2201, reflecting enhanced convective heat transfer efficiency. Additionally, at 600 mL/min, the TO film shortened the thermal equilibrium time to 150 s with a steady-state temperature of 9.4 °C, outperforming the traditional film's 210 s and 10.8 °C. The experimental results confirm the feasibility and effectiveness of the proposed model method, demonstrating that the honeycomb film designed based on the topology optimization method exhibits excellent thermal camouflage performance, which is expected to foster further application of bionic structures in microfluidic camouflage technology.