Comparative evaluations of thermofluidic characteristics of sandwich panels with X-lattice and Pyramidal-lattice cores

This study compares the thermo-fluidic characteristics of sandwich panels with the X-lattice and the Pyramidal lattice at a given porosity and surface area density. The numerical model is validated against available experimental data at first. At a given Reynolds number in the range of 3100-5700, numerical results reveal that the X-lattice sandwich panel provides a 47-60% higher average overall Nusselt number. The special topology of the X-lattice induces counter-rotating spiral primary flow and more complex secondary flows, including one which becomes a longitudinal vortex later. The flow in the Pyramidal lattice sandwich panel is composed of a parallel primary flow and a counter-rotating vortex pair entrenched in the zone behind ligaments of the Pyramidal lattice. Compared with the Pyramidal lattice sandwich panel, endwall heat transfer of the X-lattice sandwich panel is enhanced by 75-97% and the ligaments surface heat transfer is enhanced by 85-97% at a given Reynolds number. It is also found that the friction factor of the X-lattice sandwich panel is about 2 times higher for the spiral primary flow and more complex secondary flows induced by the staggered ligaments. Finally, at a given pumping power, the cooling performance of the X-lattice is much better, too. Taking the identical fabrication method and cost into account, apparently the X-lattice is superior in engineering applications. (C) 2018 Elsevier Ltd. All rights reserved.