Forced convection in additively manufactured sandwich-walled cylinders with thermo-mechanical multifunctionality

Abstract Forced convective heat transfer in lightweight sandwich-walled cylinders with quadrangle core (I type) and triangle cores (V, N, W and M type) was investigated experimentally, numerically and theoretically, targeting multifunctional applications (e.g., combustion chamber) requiring simultaneous load bearing and heat dissipation. Sandwich-walled cylinder with the N type core was fabricated using 3D-printing technology. Forced convection experiments were carried out to validate numerical simulation results and to reveal varying flow stages in the channels of the sandwich wall. Flow in these channels changed from laminar (Re 4100) as the Reynolds number was increased. With the total heat dissipation area fixed, the heat transfer performance of the quadrilateral core (I type) was better than triangular cores (V, N, W and M type). Among the triangular cores, those with homogeneous pore structure (V and N) exhibited superior heat transfer performance in comparison with the nonhomogeneous ones (W and M type). The optimal number of unit cells for each core type was determined using the theory of intersection-of-asymptotes. With the unit cell number optimized for each core, the I core exhibited the best heat dissipation performance while the M core had the worst. Under structural loading, however, the buckling resistance of the I core was not as good as the triangular ones. Thermal and mechanical synergy must be considered in the selection of sandwich core topology for multifunctional applications.