Uncoupling Coriolis Force and Rotating Buoyancy Effects on Full-Field Heat Transfer Properties of a Rotating Channel

Purpose The fluid flow in a rotating channel is obviously different from that in a stationary channel due to the existence of Coriolis force, which, in turn, enhances the heat transfer on the trailing side and reduces the heat transfer on the leading side. The purpose of this paper is to study various rib configurations combined with channel orientation on heat transfer and frictional loss in a rotating channel. Design/methodology/approach In the present study, the k-ω SST model was used as the turbulence model. The fluid flow direction in the channel is radially outward. The angle between the rotation axis and leading side is 45°. The channel aspect ratio (W/H) is 2, the blockage ratio (e/Dn ) is 0.1 and the pitch ratio (P/e) is 10. The Reynolds number is fixed at 10,000 and the rotation number varies from 0 to 0.7. Angled ribs, reversed angled ribs, standard V-shaped ribs and outer-leaning V-shaped ribs, are examined. Findings It is found that the reversed angled rib configuration and the outer-leaning V-shaped rib configuration display better heat transfer performance than the V-shaped ribs in rotating condition, which is in contrast to stationary condition. At the leading side, the reversed angled rib and the outer-leaning V-shaped rib show better performance in recovering the heat transfer recession due to the negative effects of the Coriolis force. Research limitations/implications In the present study, the fluid is incompressible with constant thermophysical properties and the flow is steady. Practical implications The results of this study will be helpful in design of ribbed channels internal cooling for turbine blade. Originality/value The results imply that the rib configuration combined with channel orientation significantly impacts the heat transfer performance in a rotating channel. The reversed angled rib and the outer-leaning V-shaped rib show better heat transfer performance than standard V-shaped ribs, especially at high Rotating numbers, which is in contrast to stationary condition. The outer-leaning V-shaped rib has a relatively good heat transfer uniformity along the widthwise direction.

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Heat Transfer of Rotating Rectangular Channel With Diamond Shaped Pin-Fin Array at High Rotation Numbers

Volume 4: Heat Transfer, Parts A and B ◽

10.1115/gt2012-68676 ◽

2012 ◽

Cited By ~ 1

Author(s):

S. W. Chang ◽

T.-M. Liou ◽

T.-H. Lee

Keyword(s):

Heat Transfer ◽

Rectangular Channel ◽

Turbine Rotor ◽

Full Field ◽

Turbine Rotor Blade ◽

Pin Fin ◽

Nusselt Numbers ◽

Static Channel ◽

Pin Fin Array ◽

Transfer Properties

This experimental study measured the detailed Nusselt numbers (Nu) distributions over two opposite leading and trailing walls of a rotating rectangular channel fitted with diamond shaped pin-fin array with radially outward flow for gas turbine rotor blade cooling applications. The combined and isolated effects of Reynolds (Re), rotation (Ro) and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and Nu) were examined at the test conditions of 5000≤Re≤15000, 0≤Ro≤0.6 and 0.0007≤Bu≤0.31. The present infrared thermography method enables the generation of full-field Nu scans over the rotating endwalls at the realistic engine Ro conditions as the first attempt to reveal the combined rotating buoyancy and Coriolis force effects on heat transfer properties. The selected heat transfer results demonstrate the Coriolis and rotating-buoyancy effects on the heat transfer performances of this rotating channel. Acting by the combined Coriolis and rotating buoyancy effects on the area-averaged heat transfer properties, the rotating leading and trailing area-averaged Nusselt numbers are modified respectively to 0.82–1.52 and 1–1.89 times of the static channel references. A set of physically consistent empirical Nu correlations was generated to permit the assessments of individual and interdependent Re, Ro and Bu effects on the area-averaged heat transfer properties over leading and trailing endwalls.

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Heat Transfer of a Rotating Rectangular Channel With a Diamond-Shaped Pin-Fin Array at High Rotation Numbers

Journal of Turbomachinery ◽

10.1115/1.4007684 ◽

2013 ◽

Vol 135 (4) ◽

Cited By ~ 3

Author(s):

S. W. Chang ◽

T.-M. Liou ◽

T.-H. Lee

Keyword(s):

Heat Transfer ◽

Rectangular Channel ◽

Turbine Rotor ◽

Full Field ◽

Turbine Rotor Blade ◽

Pin Fin ◽

Nusselt Numbers ◽

Static Channel ◽

Pin Fin Array ◽

Transfer Properties

This experimental study measured the detailed Nusselt numbers (Nu) distributions over two opposite leading and trailing walls of a rotating rectangular channel fitted with a diamond-shaped pin-fin array with radially outward flow for gas turbine rotor blade cooling applications. The combined and isolated effects of Reynolds (Re), rotation (Ro), and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and Nu¯) were examined at the test conditions of 5000 ≤ Re ≤ 15,000, 0 ≤ Ro ≤ 0.6, and 0.0007 ≤ Bu ≤ 0.31. The present infrared thermography method enables the generation of full-field Nu scans over the rotating end walls at the realistic engine Ro conditions as the first attempt to reveal the combined rotating buoyancy and Coriolis force effects on heat transfer properties. The selected heat transfer results demonstrate the Coriolis and rotating-buoyancy effects on the heat transfer performances of this rotating channel. Acting by the combined Coriolis and rotating buoyancy effects on the area-averaged heat transfer properties, the rotating leading and trailing area-averaged Nusselt numbers are modified, respectively, to 0.82–1.52 and 1–1.89 times the static channel references. A set of physically consistent empirical Nu¯ correlations was generated to permit the assessments of individual and interdependent Re, Ro, and Bu effects on the area-averaged heat transfer properties over leading and trailing end walls.

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Thermal Performance of a Radially Rotating Twin-Pass Smooth-Walled Parallelogram Channel

Journal of Turbomachinery ◽

10.1115/1.4028239 ◽

2014 ◽

Vol 136 (12) ◽

Cited By ~ 14

Author(s):

Tong-Miin Liou ◽

Shyy Woei Chang ◽

Chun-Chang Yang ◽

Yi-An Lan

Keyword(s):

Heat Transfer ◽

Thermal Performance ◽

Turbine Rotor ◽

Full Field ◽

Turbine Rotor Blade ◽

Performance Factors ◽

Square Channel ◽

Nusselt Numbers ◽

The Individual ◽

Rotating Channel

An experimental study was performed to measure the detailed heat transfer distributions, Fanning friction factors (f), and thermal performance factors (TPF) of a radially rotating twin-pass parallelogram channel. Laboratory scale full field Nusselt number (Nu) distributions over leading endwall (Leading-E), and trailing endwall (Trailing-E) of the rotating channel are measured at the test conditions of 5000 < Re < 20,000, 0 < Ro < 0.3 and 0.028 < Δρ/ρ < 0.12. A selection of Nu data illustrates the individual and interactive impacts of Re, Ro, and buoyancy (Bu) numbers on local and area-averaged heat transfer properties. Without the additional flow complexities induced by the turbulators, the degrees of Bu impacts are significantly amplified from those developed in an enhanced rotating ribbed channel. Relative to the similar rotating square twin-pass channel, the heat transfer recovery over the stable wall proceeds at the lower Ro for present rotating parallelogram channel. Accompanying with the improved heat transfer performances from the square-channel counterparts, the f values are raised. With a set of f correlations generated using the f data collected from the Leading-S and Trailing-S at isothermal conditions; the TPF values at various rotating conditions were evaluated. The heat transfer correlations that determine the area-averaged Nusselt numbers over the inlet and outlet legs and over the turning region are generated. The area-averaged Nu, f factors, and TPF determined from the present rotating parallelogram channel are compared with those reported for the rotating twin-pass channels to determine the comparatively thermal performances of the parallelogram rotating channel for turbine rotor blade cooling.

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Thermal Performance of a Radially Rotating Twin-Pass Smooth-Walled Parallelogram Channel

Volume 5A: Heat Transfer ◽

10.1115/gt2014-25322 ◽

2014 ◽

Author(s):

Tong-Miin Liou ◽

Shyy Woei Chang ◽

Chun-Chang Yang ◽

Yi-An Lan

Keyword(s):

Heat Transfer ◽

Thermal Performance ◽

Turbine Rotor ◽

Full Field ◽

Turbine Rotor Blade ◽

Performance Factors ◽

Square Channel ◽

Nusselt Numbers ◽

The Individual ◽

Rotating Channel

An experimental study was performed to measure the detailed heat transfer distributions, Fanning friction factors (f) and thermal performance factors (TPF) of a radially rotating twin-pass parallelogram channel. Laboratory scale full field Nusselt number (Nu) distributions over Leading Endwall (Leading-E) and Trailing Endwall (Trailing-E) of the rotating channel are measured at the test conditions of 5000 < Re < 20000, 0 < Ro < 0.3 and 0.028 < Δρ/ρ < 0.12. A selection of Nu data illustrates the individual and interactive impacts of Re, Ro and buoyancy (Bu) numbers on local and area-averaged heat transfer properties. Without the additional flow complexities induced by the turbulators, the degrees of Bu impacts are significantly amplified from those developed in an enhanced rotating ribbed channel. Relative to the similar rotating square twin-pass channel, the heat transfer recovery over the stable wall proceeds at the lower Ro for present rotating parallelogram channel. Accompanying with the improved heat transfer performances from the square-channel counterparts, the f values are raised. With a set of f correlations generated using the f data collected from the Leading Sidewall (Leading-S) and Trailing Sidewall (Trailing-S) at isothermal conditions; the TPF values at various rotating conditions were evaluated. The heat transfer correlations that determine the area-averaged Nusselt numbers over the inlet and outlet legs and over the turning region are generated. The area-averaged Nu, f factors and TPF determined from the present rotating parallelogram channel are compared with those reported for the rotating twin-pass channels to determine the comparatively thermal performances of the parallelogram rotating channel for turbine rotor blade cooling.

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