Numerical Investigation of Thermal and Friction Characteristics of Fuel in Modified Rhombic Fins PCHE for Aeroengine

With the continuous advancement in aeroengine performance, effective thermal management has become increasingly critical to ensure system reliability and efficiency. Printed Circuit Heat Exchanger (PCHE) emerges as pivotal components within this domain, favored for the exceptional thermal efficiency and compact structure. In this study, the thermal and friction characteristics of PCHE channels with modified rhombic fins are investigated. As a primary heat sink of aeroengines, fuel serves as the working fluid in this research. Employing numerical method, the investigation analyzes the impact of modified rhombic fin structures and the physical property of fuel on the thermal and friction characteristics of PCHE. The variations in the heat transfer and resistance coefficients under diverse operational conditions are analyzed and the comprehensive thermal performance of the modified rhombic fin structures of PCHE is evaluated. The findings reveal a notable decline in heat transfer with increasing inlet temperature of the hot fluid, ranging from 400K to 470K. This decline is primarily attributed to the decrease in the thermal conductivity of the fuel. In laminar flow, heat transfer is predominantly governed by conduction rather than convection. Conversely, resistance is less sensitive to changes in the inlet temperature. The research analyzes the effect of Reynolds number (220-1020) on heat transfer and resistance. At higher Reynolds numbers, the heat transfer coefficient exhibits more significant changes, while the drag coefficient shows more substantial variations at lower Reynolds numbers. Additionally, the variation pattern of the evaluation index for the Colburn heat transfer factor ratio to the friction factor (j/f1/3) in the modified rhombic fins heat transfer unit is elucidated. The j/f1/3 decreases by 30% as the Reynolds number increases from 220 to 620, but it decreases only slightly at higher Reynold numbers. Based on the numerical results, empirical correlations for the Nusselt number and resistance coefficient of the PCHE with modified rhombic fins have been established. In addition, this paper presents a flow field analysis along the modified rhombic fin channels. Despite the general trend of decreasing pressure along the passage, the local sectional pressure is compensated as the flow channel expands. Due to the flow resistance created by the edge of the modified rhombic fins, the flow velocity locally decreases in the regions between the leading edge and trailing edge. The study of thermal and friction characteristics in modified rhombic fins PCHE can inform future design iterations aimed at enhancing performance of aeroengine.