On the coupled integration of ducted heat-exchanger systems for aviation

Abstract

This paper investigates the design and aerothermal optimization of duct geometries with integrated finned heat exchangers. The primary focus of the paper is to investigate how the performance varies with heat exchanger inlet area and total duct length. The results provide new insights into the underlying trade-offs. Heat exchangers with a larger area result in lower losses over the heat exchanger matrix but incur increased losses in the ducts. Additionally, shorter ducts lead to higher losses over the heat exchanger due to the reduced diffusive capacity, while duct losses remain largely unchanged. The study also investigates the effects of the matrix configuration in the heat exchanger overall aerodynamic performance. A fixed and optimized geometry is therefore selected and the impact of decreased flow restriction in the heat-exchanger transversal direction is investigated. The results show that removing the fins, leads to a negligible increase in the normalized losses from 1.146 to 1.159, indicating that the pressure drop across the heat exchanger matrix is the primary driver of diffusion, rather than by the finned structure itself.