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

2014 ◽  
Vol 136 (12) ◽  
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.

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

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.

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

2012 ◽  
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.

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

2013 ◽  
Vol 135 (4) ◽  
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.

scholarly journals Heat Transfer Enhancement by Detached S-Ribs for Twin-Pass Parallelogram Channel

Inventions ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 50 ◽  
Author(s):  
Shyy Chang ◽  
Wei-Ling Cai ◽  
Ruei-Jhe Wu
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Reynolds Numbers ◽  
Test Channel ◽  
Pressure Drops ◽  
Transfer Rates ◽  
Performance Factors ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Measured Pressure

Detached S-ribs are proposed to arrange in the stagger manner along two parallelogram straight channels interconnecting with a 180° smooth-walled sharp bend for heat transfer enhancements. The detailed Nusselt number distributions over the two opposite channel endwalls at Reynolds numbers of 5000, 7500, 10,000, 12,500, 15,000 and 20,000 are measured using the steady-state infrared thermography method. The accompanying Fanning friction factors are evaluated from the measured pressure drops across the entire test channel. Having acquired the averaged heat transfer properties and Fanning friction factors, the thermal performance factors are determined under the criterion of constant pumping power consumptions. With the regional accelerated flows between the detached S-ribs and the channel endwall, the considerable heat transfer elevations from the Dittus–Boelter correlation levels are achieved. The comparative thermal performances between the two similar twin-pass parallelogram channels with detached 90° and S-ribs disclose the higher regional heat transfer rates over the turning region and the larger Fanning frictions factors, leading to the lower thermal performance factors, for present test channel with the detached S-ribs. To assist design applications, two sets of empirical correlations evaluating the regionally averaged Nusselt numbers and Fanning friction factors are devised for present twin-pass parallelogram channel with the detached S-ribs.

Latticework (Vortex) Cooling Effectiveness: Part 2 — Rotating Channel Experiments

2004 ◽  
Author(s):  
S. Acharya ◽  
Fuguo Zhou ◽  
Jonathan Lagrone ◽  
Gazi Mahmood ◽  
Ronald S. Bunker
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Density Ratio ◽  
Transfer Coefficients ◽  
Performance Factors ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Smooth Channel ◽  
Rib Turbulators ◽  
Density Ratios

The heat transfer and pressure drop characteristics of latticework coolant blade passages have been investigated experimentally under conditions of rotation. Stationary studies with the latticework configuration have shown potential advantages including spatially-uniform streamwise distributions of the heat transfer coefficient, greater blade strength, and enhancement levels comparable to conventional rib turbulators. In the present study, a latticework coolant passage, with orthogonal-ribs, is studied in a rotating heat transfer test-rig for a range of Reynolds numbers (Res), Rotation numbers (Ros), and density ratios. Measurements indicate that for Res≥20,000, the latticework coolant passage provides very uniform streamwise distributions of the Nusselt number (Nus) with enhancement levels (relative to smooth-channel values) in the range of 2.0 to 2.5. No significant dependence of Nus on Ros and density ratio is observed except at lower Res values (≤10,000). Nusselt numbers are highest immediately downstream of a turn indicating that bend-effects play a major role in enhancing heat transfer. Friction factors are relatively insensitive to Ros, and thermal performance factors at higher Res values appear to be comparable to those obtained with conventional rib-turbulators. The present study indicates that latticework cooling geometry can provide comparable heat transfer enhancements and thermal performance factors as conventional rib-turbulators, with potential benefits of streamwise uniformity in the heat transfer coefficients and added blade strength.

Detailed Heat Transfer Distributions and Pressure Drop Measurements for a Rotating Parallelogram Channel With Radially Outward Flow

2011 ◽  
Author(s):  
S. W. Chang ◽  
T.-M. Liou ◽  
T.-H. Lee
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Test Channel ◽  
Transfer Data ◽  
Performance Factors ◽  
Nusselt Numbers ◽  
Test Conditions ◽  
Present Test ◽  
First Time ◽  
Rotating Channel

This experimental study examines the pressure drop coefficients (f) and the detailed Nusselt numbers (Nu) distributions over two opposite leading and trailing walls roughened by 45° ribs for a rotating parallelogram channel with radially outward flow. For the first time the isolated effects of Reynolds (Re), rotation (Ro) and buoyancy (Bu) numbers on local and area averaged Nusselt numbers (Nu and Nu) measured from the infrared thermography method were successfully examined at the parametric conditions of 5000≤Re≤15000, 0≤Ro≤0.3 and 0.001≤Bu≤0.23 for the single-pass parallelogram channel. A set of selected heat transfer data illustrates the Coriolis and rotating-buoyancy effects on the detailed Nu distributions and the area-averaged heat transfer performances of the rotating parallelogram channel. With the consideration of the f data generated at the isothermal conditions, the thermal performance factors (η) for this radially rotating channel were evaluated. The Nusselt numbers obtained from the leading and trailing walls of the rotating test channel fall in the respective ranges of 0.78–1.34 and 1.09–1.38 times of the stationary levels; while the η factors are in the range of 0.979–1.575 for the present test conditions.

Heat Transfer and Flow Characteristics of Two-Pass Parallelogram Channels With Attached and Detached Transverse Ribs

2016 ◽  
Author(s):  
Tong-Miin Liou ◽  
Shyy-Woei Chang ◽  
Yi-An Lan ◽  
Shu-Po Chan ◽  
Yu-Shuai Liu
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Flow Characteristics ◽  
Height Ratio ◽  
Differential Heat ◽  
Flow Measurements ◽  
Full Field ◽  
Performance Factors ◽  
Nusselt Numbers ◽  
Design Activities

The full-field endwall Nusselt number (Nu) distributions and flow field are presented respectively using steady-state infrared thermography and particle image velocimetry (PIV) for the two-pass parallelogram channels with attached and detached transverse ribs. These square transverse ribs on two opposite channel endwalls are in-line arranged with rib-height to duct-height ratio of 0.1 and rib-pitch to rib-height ratio of 10. For the detached ribs, the detached distance between rib and channel endwall is 0.38 rib height. With the measurements of Fanning friction factor (f), heat transfer distributions and flow field features, the thermal performance factors (TPF) for the attached and detached rib cases are comparatively examined. A set of Nu, f and TPF results with the associated flow measurements at the test conditions of 5,000≤Re≤20,000 is selected to disclose the differential heat transfer enhancement mechanisms and heat transfer efficiencies between the attached and detached ribbed channels. Empirical correlations evaluating the endwall area-averaged Nusselt numbers (Nu) and f factors are devised to assist the relevant design activities.

Heat Transfer and Flow Characteristics of Two-Pass Parallelogram Channels With Attached and Detached Transverse Ribs

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
T. M. Liou ◽  
S. W. Chang ◽  
Y. A. Lan ◽  
S. P. Chan ◽  
Y. S. Liu
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Height Ratio ◽  
Differential Heat ◽  
Flow Measurements ◽  
Number Range ◽  
Full Field ◽  
Performance Factors ◽  
Nusselt Numbers ◽  
Design Activities

The full-field Nusselt number (Nu) distributions and flow fields are presented, respectively, using steady-state infrared thermography (IR) and particle image velocimetry (PIV) in the two-pass parallelogram channels with attached and detached transverse ribs. These square transverse ribs on two opposite channel walls are in-line arranged with rib-height to duct-height ratio of 0.1 and rib pitch-to-height ratio of 10. For the detached ribs, the detached distance between rib and channel wall is 0.38 rib height. With the measurements of Fanning friction factor (f), the thermal performance factors (TPF) for the attached and detached-rib cases are comparatively examined. A set of Nu, f, and TPF with the associated flow measurements at the Reynolds number range of 5000 ≤ Re ≤ 20,000 is selected to disclose the differential heat transfer mechanisms and efficiencies between the attached and detached ribbed channels. Empirical correlations evaluating the area-averaged Nusselt numbers (Nu¯) and f factors are devised to assist the relevant design activities.

Latticework (Vortex) Cooling Effectiveness: Rotating Channel Experiments

2004 ◽  
Vol 127 (3) ◽  
pp. 471-478 ◽  
Author(s):  
S. Acharya ◽  
F. Zhou ◽  
J. Lagrone ◽  
G. Mahmood ◽  
R. S. Bunker
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Density Ratio ◽  
Transfer Coefficients ◽  
Performance Factors ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Smooth Channel ◽  
Rib Turbulators ◽  
Density Ratios

The heat transfer and pressure drop characteristics of latticework coolant blade passages have been investigated experimentally under conditions of rotation. Stationary studies with the latticework configuration have shown potential advantages including spatially-uniform streamwise distributions of the heat transfer coefficient, greater blade strength, and enhancement levels comparable to conventional rib turbulators. In the present study, a latticework coolant passage, with orthogonal-ribs, is studied in a rotating heat transfer test-rig for a range of Reynolds numbers (Res), Rotation numbers (Ros), and density ratios. Measurements indicate that for Res⩾20,000, the latticework coolant passage provides very uniform streamwise distributions of the Nusselt number (Nus) with enhancement levels (relative to smooth-channel values) in the range of 2.0–2.5. No significant dependence of Nus on Ros and density ratio is observed except at lower Res values (⩽10,000). Nusselt numbers are highest immediately downstream of a turn indicating that bend-effects play a major role in enhancing heat transfer. Friction factors are relatively insensitive to Ros, and thermal performance factors at higher Res values appear to be comparable to those obtained with conventional rib-turbulators. The present study indicates that latticework cooling geometry can provide comparable heat transfer enhancements and thermal performance factors as conventional rib-turbulators, with potential benefits of streamwise uniformity in the heat transfer coefficients and added blade strength.

Influence of Radial Rotation on Heat Transfer in a Rectangular Channel With Two Opposite Walls Roughened by Hemispherical Protrusions at High Rotation Numbers

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Miin. Liou ◽  
Wei-Chun Chen
Keyword(s):  
Heat Transfer ◽  
Infrared Thermography ◽  
Rotation Number ◽  
Rectangular Channel ◽  
Flow Region ◽  
Transfer Data ◽  
Nusselt Numbers ◽  
Rotation Numbers ◽  
Heat Transfer Correlations ◽  
Rotating Channel

Detailed heat transfer distributions over two opposite leading and trailing walls roughened by hemispherical protrusions were measured from a rotating rectangular channel at rotation number up to 0.6 to examine the effects of Reynolds (Re), rotation (Ro), and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and Nu¯) using the infrared thermography. A set of selected heat transfer data illustrates the Coriolis and rotating buoyancy effects on the detailed Nu distributions and the area-averaged heat transfer performances of the rotating channel. The Nu¯ for the developed flow region on the leading and trailing walls are parametrically analyzed to devise the empirical heat transfer correlations that permit the evaluation of the interdependent and individual Re, Ro, and Bu effect on Nu¯.

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