Heat Transfer Mechanism Of Composite Sandwich Structure With Lattice Cores

As a new ultra-lightweight high strength structural material, composite structural material with periodic lattice cores has prospects to be applied widely in the aerospace field. In addition to having excellent mechanical properties, it also has potential superiority to achieve multifunctional integration, such as heat dissipation, noise reduction, energy absorption, and vibration isolation.Because of the exist of continuous channel within the sandwich structure with truss cores, auxiliary additional fluid can flow in channel, while heat can also be transferred, so this structure is a good heat exchanger。However, the property of carbon fiber composite material is greatly affected by temperature, so internal channel can be utilized to improve the heat transfer performance of the structure and decrease the overall temperature of the structure by forced convection, in order to meet the demand for temperature control and achieve integration of heat and force and improve structural reliability finally.In this paper, computational fluid dynamics software FLUENT is used to simulate heat transfer characteristics and thermal behavior of composite sandwich structure with truss cores, which is loaded a constant temperature loading and forced convection condition of auxiliary additional fluid. The simulation results confirm that the above conditions, heat transfer performance of composite sandwich structure is far weak than that of metallic sandwich structure, but in case of the introduction of flow convection, heat transfer performance of composite sandwich structure improves more observably than that of metallic structure. The thesis analyses the distribution and characteristics of fluid field, such as pressure field, velocity field, and temperature field. The influence of sandwich structural material morphology on the endwall flow and heat transfer patterns in a unit cell is described in detail. The heat transfer performance of the structure was characterized and assessed by Reynolds number, Nusselt number, the pressure drop coefficient, which are three non-dimensional parameters measured by unit cell characteristic length of sandwich structure. The concepts of minimum permeability, maximum permeability and horizontal permeability of temperature are introduced to more visually characteristic the heat transfer performance of the structure.In addition, the relationships between the angleωand the performance index and characteristic parameters were discussed and summarized. It's also compared between sandwich structure with tetrahedral cores and sandwich structure with pyramidal cores.