Delta-Winglet-Pair for Enhancing Cooling Performance of a Single Dimple Imprinted Internal Channel

Seok Min Choi, Hyun Goo Kwon, Seungyeong Choi, Minho Bang, Hee Koo Moon, Hyung Hee Cho

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3 Citations (Scopus)


Improving the cooling performance of internal channels is important to extend the lifespan of hot components exposed to heat in many types of machinery. This study was performed to examine the effects of placing a delta-winglet-pair (DWP) upstream of a single dimple in an internal cooling channel. The local heat/mass transfer coefficients (H/MTCs) were measured in the vicinity of the dimple by the naphthalene sublimation method (NSM). The cooling performances under laminar, transitional, and turbulent flow conditions were compared at different values of the DWP incidence angle (β). The DWP enhanced local H/MTCs within the dimple cavity due to intensified secondary vortices. With increasing the DWP incidence angle, the distance between the symmetrical vortices increased resulting in a different level of H/MTC enhancement. The optimum DWP incidence angle ranged between 30<β<45 depending on the flow condition. The resulting area-averaged H/MTCs clearly indicated enhancement from the DWP. Under the laminar flow conditions, the H/MTCs were enhanced by 87%–125% from installing the DWP. The absolute H/MTCs were highest under the transitional flow conditions. Based on the present investigation, the installation of the DWP in the dimpled channel is highly recommended for both laminar and transitional flow conditions.

Original languageEnglish
Article number121647
JournalInternational Journal of Heat and Mass Transfer
Publication statusPublished - 2021 Oct

Bibliographical note

Funding Information:
This work was supported by the Human Resources Development program (No.20204030200110) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government Ministry of Trade, Industry, and Energy. This work was supported by the UAV High Efficiency Turbine Research Center program of Defense Acquisition Program Administration and Agency for Defense Development.

Publisher Copyright:
© 2021

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes


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