Numerical Investigation on the Performance of Plate Heat Exchangers for Core and Bypass Ducts in High-Speed Micro Aero-Engines

Abstract

This paper utilizes the Computational Fluid Dynamics (CFD) method to systematically investigate the influence of cold-side (Recold) and hot-side (Rehot) inlet Reynolds numbers on the heat transfer, flow performance, and thermodynamic irreversibility (entropy generation) of an annular plate heat exchanger integrated into a micro aero-engine. The research results indicate that as the cold-side Recold increases, the cold-side convective heat transfer coefficient (hcold) is significantly enhanced; however, the high-velocity fluid experiences a pressure-drop-induced expansion cooling effect in the latter half of the channel, which suppresses the gas temperature rise—this unique physical mechanism is explicitly confirmed through a comparative simulation with an incompressible fluid model. Simultaneously, increasing the hot-side Rehot significantly boosts the system's average heat transfer rate and the overall heat transfer coefficient (U), with an exceptional growth rate of 91.13% for the average heat transfer rate when Rehot increases from 2000 to 5000. Furthermore, the entropy generation analysis shows that the cold-side Reynolds number is more sensitive to the system's total entropy production, suggesting its optimization potential is superior to that of the hot side. This study provides crucial theoretical basis and optimization guidelines for the design of high-efficiency, low-resistance heat exchangers operating under the high-Mach number conditions typical of micro aero-engines.