The Convective Heat Transfer Performance Of Curved-crease Folded Sandwich Structure

The folded core sandwich panel may be applied in the thermal protection system of advanced hypersonic flight vehicle,for its various advantages such as light-weight,high specific strength and stiffness,easy to manufacture,designable.Among those folded cores,curved-crease structure has better mechanical capacities than straight-crease structures in energy absorption,shock resistance and dynamic load bearing.Especially,the smooth transition of curved-crease folded structure causes lower pressure drop loss when being replenished coolant in its cavities,which saves the energy of pressure pump.In this research,the heat exchange performance of curved-crease sandwich panel under forced convection is studied.Through the physical field simulation of CFX software,the pressure,velocity and temperature field,along with the mechanism of periodic distribution,inlet and outlet effect,and the temperature distribution of feature points and line segment is analyzed.The comparison of heat transfer performance between straight-crease and curved-crease under same condition is made by introducing indicator ? to evaluate their heat transfer efficiency,and curved-crease folded structure is demonstrated to be more efficient and economical.After that,the influence of inlet velocity on heat transfer capacity and pressure loss is analyzed,and the velocity threshold is obtained through the variation of maximum temperature under changing inlet velocity.On basis of that,the optimization of geometric parameters H,L and W is made,which objectives are maximum heat transfer efficiency and minimum relative density.Latin Hypercube Sampling is used in design of experiment,and Kriging surrogate model is used to improve calculate efficiency.After the Pareto Multi-Objective Genetic Algorithm optimization front is obtained,the integral and unitary sensitivity analysis between design variables and objectives are made.It is found that the tortuosity of curved-crease folded structure is the most sensitive variable.The ultimate optimal solution set provides reference to practical issues.