Session: 13-05: Influence of manufacturing techniques on heat transfer

Paper Number: 153071

Flow and Heat Transfer Characteristics of Additively Manufactured Mini Channels 

The development of Additive Manufacturing (AM) methods has enabled highly complex designs feasible to manufacture. This advancement has in turn rendered possible the fabrication of intricate cross sectional geometries that may be used as cooling passages for the future propulsion engines. These internal cooling channels may have rougher surfaces and smaller hydraulic diameters, approaching mini-channel dimensions around 1 mm, compared to conventional designs.
The internal AM channel characteristics complicate the determination of the friction factor and heat convection coefficient, as they deviate from existing correlations. In this work, an AM mini-channel with relative surface roughness $\varepsilon/D_{H} = 0.025$ and a rectangular hydraulic diameter of ${D}_{H}$ = 1.78 mm is experimentally tested under variable mass flow ($10 - 35\cdot{10}^{-3}~kg/s$) and heat flux ($100 - 250~kW/m^{2}$) conditions. For the data demonstration the j factor of the Chilton-Colburn modified analogy is used, to combine data of different studies.
The friction factor demonstrated transition to fully turbulent flow at Re $\approx$ ${10}^{4}$ whereas for higher values of Re, the data showed satisfying agreement with values predicted by the Colebrook equation.
The convective heat transfer coefficient correlated to the Gnielinski correlation for the range of Re number applied, but the data trendline showed a steeper slope in the j-Re diagram. This behavior could be an indication of the problem being dependent to additional parameters other than the well-established Re, Pr and f numbers.

Presenting Author: Dimitrios Vrocharis University of New Mexico

Presenting Author Biography: Dimitrios Vrocharis joined the PhD program of University of New Mexico as a Research Assistant in January 2024. He received a diploma in Mechanical Engineering from the University of Western Macedonia - Greece in 2023. During his undergraduate program, he was a member of the 'ASPiRE' aerodynamics team. He designed and analyzed a fixed-wing drone that won the Simulation Award in the international competition 'UAS Challenge 2023', in UK. The focus of his research is modeling and experimentation of heat transfer in advanced propulsion and power generation engines.

Authors:

Dimitrios Vrocharis University of New Mexico
Georgios Koutsakis University of New Mexico