Development of a compact 3D manifold design for cooling of internal heatsinks using external airflow

External airflow plays a crucial role in thermal management across many vehicle types, often relying on forced convection through plate-fin heatsinks. However, this airflow frequently contains dust, particles, and foreign object debris (FOD), which can cause wear, clogging, and damage to conventional heatsinks. This study introduces a novel three-dimensional (3D) manifold architecture specifically designed to mitigate the impact of FOD on air-cooled heatsinks in harsh environments. Unlike traditional manifolds that channel all airflow through an internal heatsink, the proposed design features a unique ‘multi-path’ configuration: a portion of the air is drawn through the internal heatsink, while the remainder may flow directly through the manifold itself. This approach improves resilience to debris-laden flows compared to conventional manifolds. The proposed manifold, referred to as ‘CONDIV’, is constructed from angled fins arranged to form an array of converging–diverging channels, which generate alternating high and low pressure regions when exposed to external airflow. This pressure differential effectively draws a portion of external airflow through the protected internal heatsink while allowing debris and the remaining air to pass through the manifold directly, minimizing obstruction and reducing the risk of clogging. A comprehensive parametric optimization of the manifold and heatsink geometries was conducted using 3D simulations in ANSYS Fluent. Results demonstrate that the ‘CONDIV’ manifold achieves higher performance coefficients compared to traditional plate-fin heatsinks of equivalent mass. In fully ducted flow scenarios, the proposed design can attain 8.3–32.6% higher base heat fluxes, and 3.4–22.5% improvements when flow bypass is allowed. These findings highlight the potential of this innovative manifold architecture to enhance vehicle cooling performance in challenging environments involving debris-laden airflow. • Introduces 3D converging–diverging (CONDIV) manifold enabling partial flow ingestion. • Demonstrates debris-tolerant performance in ducted and bypass conditions. • CFD simulations and experimental validation conducted across multiple variants. • Presents detailed flow visualizations to explain flow mechanisms and performance. • Shows CONDIV outperforms plate-fin heatsinks by up to 33% (ducted) and 23% (bypass).