Analysis of Flow Field Characteristics in Proton Exchange Membrane Fuel Cells Based on Bio-Inspired Leaf-Vein Structures

Traditional fuel cell flow field structures often suffer from non-uniform current and reactant distributions, which hinders reaction efficiency and fuel utilization. To address these issues, this study establishes a bio-inspired leaf-vein PEMFC simulation platform based on FLUENT, investigating the impact of various flow field geometries on species distribution, pressure drop, and electrochemical performance. Results show that when the primary–secondary vein angle is set to 30°, the average oxygen concentration at the catalyst layer interface reaches 3.05 mol/m³, and the current density is well balanced with an average value of 0.70 A/cm². Meanwhile, the water saturation at the interface is reduced to 0.13 or below. At 0.4 V, the peak current density reaches 0.97 A/cm² with a water removal efficiency exceeding 94%. Introducing secondary branches leads to a 6.3% increase in average reactant concentration at the GDL–CL interface and approximately 20% reduction in pressure drop. Moreover, the high-current-density region shifts about 20% toward the outlet, indicating a better distribution of mass transfer pathways. Overall, under the condition of over 94% water removal efficiency, the parasitic power loss is reduced by approximately 8%.