Numerical Investigation of Flow and Heat Transfer in Rectangular Microchannels with and without Semi-Elliptical Protrusions

Haiou Sun, Hao Fu, Lanyi Yan, Hongfei Ma, Yigang Luan and Franco Magagnato
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Haiou Sun: College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China
Hao Fu: College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China
Lanyi Yan: College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China
Hongfei Ma: College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China
Yigang Luan: College of Power and Energy Engineering, Harbin Engineering University, Harbin 150001, China
Franco Magagnato: Institute of Fluid Mechanics, Karlsruhe Institute of Technology, Kaiserstra ße 10, Bldg. 10.23., 76131 Karlsruhe, Germany

Energies, 2022, vol. 15, issue 13, 1-30

Abstract: Micro-cooling is a growing trend in the field of turbine blade cooling. Technical difficulties in the experiments of large-aspect-ratio rectangular microchannels that are commonly used in the turbine blades cause the rareness of related literature. In this study, the flow characteristics and heat transfer performance of the microchannels with and without semi-ellipsoidal protrusions, whose height is 0.6 mm and width is 9 mm, are numerically investigated. In the microchannel without protrusions, when 2214 < Re < 3589, the velocity has a Λ-shaped distribution, resulting in a Λ-shaped Nu distribution on the wall. When Re > 3760, it is worth noting that from the sidewall to the middle of the channel, Nu first decreases and then increases. In the microchannel with protrusions, when Re < 1214, the turbulence formed by the protrusion is almost all behind it and does not spread to both sides. When 1214 < Re < 2374, the turbulence caused by the protrusions gradually spreads to the middle and both sides of the channel with the increase in Re . When 2374 < Re < 3815, the turbulence caused by two columns of protrusions meet in the middle of the channel and forms stronger turbulence downstream. When Re > 3815, the flow is all turbulent. The protrusions enhance the irreversibility of heat transfer and friction. The performance evaluation criteria (PEC) increases first and then decreases with Re and the maximum value is 1.80 at Re = 2004. In this work, the details that are difficult to obtain in experiments are fully analyzed to provide suggestions for the design of micro-cooling structures in gas turbine blades.

Keywords: microchannel; turbulence generation; flow and heat transfer; heat transfer enhancement (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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