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Toward specification of complex additive manufactured metal surfaces for optimum heat transfer

Published

Author(s)

Kuldeep Mandloi, Christopher Evans, Jason Fox, Harish Cherukuri, Jimmie Miller, Angela Allen, David Deisenroth, Alkan Donmez

Abstract

Metal additive manufacturing (AM) offers the possibility of incorporating cooling channels into components in high-temperature applications. Additionally, it has the prospect of optimizing cooling channel geometry unconstrained by geometric limitations of conventional machining processes. Such channels will necessarily have surfaces manufactured at various orientations resulting in different topographies that may influence heat transfer. Numerous studies have shown that conventional (amplitude) roughness parameters do not discriminate between topographies produced under different build conditions – but such descriptions have been used in studies of microchannel heat exchanger performance. The motivation behind this study is to explore the correlation between AM roughness characteristics (weld tracks amplitudes/wavelengths and their orientation, spatter, etc.) and the resulting effect on heat transfer and pressure drop in fabricated microchannels. Computational fluid dynamics (CFD) models for mini-channels using Star CCM+ were developed by acquiring the roughness data from the real AM surfaces with various roughness parameters such as different wavy patterns and the build directions. Simplified versions of measured surface topographies reduce the computational overhead. The pressure drops across the mini-channels and Nusselt (Nu) numbers were computed and analyzed for these cases under both laminar and turbulent flow conditions. Significant differences in the Nu numbers and pressure drops were observed across the different AM surfaces considered. Further CFD modeling of mini-channels with different wavy surfaces helped in exploring the suitable dimensions for the mini-channel experimental set-up and also enabled exploration of the Reynolds number range to consider experimentally. Heat balance considerations have been used to validate the current findings. An experimental set-up is under development to compare models in an idealized set-up. Initial results from the experiments are also described.
Proceedings Title
Joint Special Interest Group meeting between euspen and ASPE Advancing Precision in Additive Manufacturing
Conference Dates
September 21-23, 2021
Conference Location
St. Gallen, CH

Keywords

Cooling, Experimentation, Fluid, Modeling, Surface Roughness

Citation

Mandloi, K. , Evans, C. , Fox, J. , Cherukuri, H. , Miller, J. , Allen, A. , Deisenroth, D. and Donmez, A. (2021), Toward specification of complex additive manufactured metal surfaces for optimum heat transfer, Joint Special Interest Group meeting between euspen and ASPE Advancing Precision in Additive Manufacturing, St. Gallen, CH, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932800 (Accessed July 2, 2022)
Created September 23, 2021, Updated February 7, 2022