Flow in a simulated turbine blade cooling channel with spatially varying roughness caused by additive manufacturing orientation

Stephen T. McClain, Jacob C. Snyder, David R. Hanson, Robert F. Kunz, Emily Cinnamon, Karen A. Thole

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Because of the effects of gravity acting on the melt region created during the laser sintering process, additively manufactured surfaces that are pointed upward have been shown to exhibit roughness characteristics different from those seen on surfaces that point downward. For this investigation, the Roughness Internal Flow Tunnel (RIFT) and computational fluid dynamics models were used to investigate flow in channels with different roughness on opposing walls of the channel. Three rough surfaces were employed for the investigation. Two of the surfaces were created using scaled, structured-light scans of the upskin and downskin surfaces of an Inconel 718 component which was created at a 45 angle to the printing surface and documented by Snyder et al. [1]. A third rough surface was created for the RIFT investigation using a structured-light scan of a surface similar to the Inconel 718 downskin surface, but a different scaling was used to provide larger roughness elements in the RIFT. The resulting roughness dimensions (Rq/Dh) of the three surfaces used were 0.0064, 0.0156, and 0.0405. The friction coefficients were measured over the range of 10,000 < ReDh < 70,000 for each surface opposed by a smooth wall and opposed by each of the other rough walls. At multiple ReDh values, x-array hot film anemometry was used to characterize the velocity and turbulence profiles for each roughness combination. The friction factor variations for each rough wall opposed by a smooth wall approached complete turbulence. However, when rough surfaces were opposed, the surfaces did not reach complete turbulence over the Reynolds number range investigated. The results of inner variable analysis demonstrate that the roughness function (ΔU+) becomes independent of the roughness condition of the opposing wall providing evidence that Townsend's Hypothesis holds for the relative roughness values expected for additively manufactured turbine-blade cooling passages.

Original languageEnglish (US)
Title of host publicationHeat Transfer
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791884164
DOIs
StatePublished - 2020
EventASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition, GT 2020 - Virtual, Online
Duration: Sep 21 2020Sep 25 2020

Publication series

NameProceedings of the ASME Turbo Expo
Volume7A-2020

Conference

ConferenceASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition, GT 2020
CityVirtual, Online
Period9/21/209/25/20

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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