Heat Transfer in Two-Pass Rotating Rectangular Channels (AR=1:2 and AR=1:4) With 45° Angled Rib Turbulators

2004 ◽  
Author(s):  
Wen-Lung Fu ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Flow Direction ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Rotation Effect ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Rectangular Channels ◽  
Rotation Numbers ◽  
Rib Turbulators

This paper reports the heat transfer coefficients in two-pass rotating rectangular channels (AR=1:2 and AR=1:4) with rib roughened walls. Rib turbulators are placed on the leading and trailing walls of the two-pass channel at an angle of 45° to the flow direction. Four Reynolds numbers are considered from 5000 to 40000. The rotation numbers vary from 0.0 to 0.3. The ribs have a 1.59 by 1.59 mm square cross section. The rib height-to-hydraulic diameter ratios (e/Dh) are 0.094 and 0.078 for AR=1:2 and AR=1:4, respectively. The rib pitch-to-height ratio (P/e) is 10 for both cases, and the inlet coolant-to-wall density ratio (Δρ/ρ) is maintained around 0.115. For each channel, two channel orientation are studied, 90° and 45° with respect to the plane of rotation. The results show that the rotation effect increased the heat transfer on trailing wall in the first pass, but reduced the heat transfer on the leading wall. For AR=1:4, the minimum heat transfer coefficient was 25% of the stationary value. However, the rotation effect reduced the heat transfer difference between the leading and trailing walls in the second pass.

Heat Transfer in Two-Pass Rotating Rectangular Channels (AR=1:2 and AR=1:4) With 45 Deg Angled Rib Turbulators

2005 ◽  
Vol 127 (1) ◽  
pp. 164-174 ◽  
Author(s):  
Wen-Lung Fu ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Flow Direction ◽  
Density Ratio ◽  
Reynolds Numbers ◽  
Rotation Effect ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Rectangular Channels ◽  
Rotation Numbers ◽  
Rib Turbulators

This paper reports the heat transfer coefficients in two-pass rotating rectangular channels (AR=1:2 and AR=1:4) with rib roughened walls. Rib turbulators are placed on the leading and trailing walls of the two-pass channel at an angle of 45 deg to the flow direction. Four Reynolds numbers are considered from 5000 to 40 000. The rotation numbers vary from 0.0 to 0.3. The ribs have a 1.59 by 1.59 mm square cross section. The rib height-to-hydraulic diameter ratios e/Dh are 0.094 and 0.078 for AR=1:2 and AR=1:4, respectively. The rib pitch-to-height ratio P/e is 10 for both cases, and the inlet coolant-to-wall density ratio (Δρ/ρ) is maintained around 0.115. For each channel, two channel orientations are studied, 90 deg and 45 deg with respect to the plane of rotation. The results show that the rotation effect increased the heat transfer on trailing wall in the first pass, but reduced the heat transfer on the leading wall. For AR=1:4, the minimum heat transfer coefficient was 25% of the stationary value. However, the rotation effect reduced the heat transfer difference between the leading and trailing walls in the second pass.

Heat Transfer in Two-Pass Rotating Rectangular Channels (AR=1:2 and AR=1:4) With Smooth Walls

2005 ◽  
Vol 127 (3) ◽  
pp. 265-277 ◽  
Author(s):  
Wen-Lung Fu ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Rotation Effect ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Rectangular Channels ◽  
Rotation Numbers ◽  
Sharp Turn ◽  
First Pass ◽  
Turn Region

This paper reports the heat transfer coefficients in two-pass rotating rectangular channels [aspect ratio (AR=1:2 and AR=1:4)] with smooth walls. The experiments are conducted at four Reynolds numbers: 5000, 10,000, 25,000, and 40,000. The rotation numbers vary from 0.0 to 0.21 and 0.0 to 0.3 for AR=1:2 and AR=1:4, respectively. For each channel, two channel orientations are studied, 90° and 45° with respect to the plane of rotation. The results showed that the 180° sharp turn significantly enhanced heat transfer on both the leading and trailing surfaces in the turn region for both nonrotating and rotating channels. The results also showed that the rotation effect increased the heat transfer on the trailing surface in the first pass, but reduced the heat transfer on the leading surface. However, the heat transfer difference between the leading and trailing walls in the second pass is relatively small compared to the first pass due to strong turn effect.

Heat Transfer in Two-Pass Rotating Rectangular Channels (AR=2:1) With Discrete V-Shaped and Discrete Angled Rib Turbulators

2004 ◽  
Author(s):  
Wen-Lung Fu ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Rectangular Channel ◽  
Density Ratio ◽  
Transfer Coefficients ◽  
Rotating Speed ◽  
Heat Transfer Coefficients ◽  
Rectangular Channels ◽  
Internally Cooled ◽  
Rib Turbulators ◽  
Channel Aspect Ratio

This paper reports the heat transfer coefficients in a two-pass rotating, rectangular channel with ribs, applicable to an internally cooled turbine blade. The channel aspect ratio is 2:1. Five different turbulators are studied: 45° angled ribs, V-shaped ribs, discrete 45° angled ribs, discrete V-shaped ribs, and crossed V-shaped ribs. The ribs are placed on the leading and trailing surfaces. The Reynolds numbers range from 5000 to 40000. The corresponding rotation numbers vary from 0.21 to 0.026 for a fixed rotating speed of 550 rpm. The rib height-to-hydraulic diameter ratio (e/D) is 0.094, the rib pitch-to-height ratio (P/e) is 10, and the inlet coolant-to-wall density ratio (Δρ/ρ) is maintained around 0.115. For each case, two channel orientations are studied, 90° and 135° with respect to the plane of rotation. The results show the V-shaped ribs and discrete V-shaped ribs have higher heat transfer enhancement than the 45° angled ribs and discrete 45° angled ribs for both rotating and non-rotating cases.

Heat Transfer in Rotating Serpentine Coolant Passage With Ribbed Walls at Low Mach Numbers

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Shang-Feng Yang ◽  
Je-Chin Han ◽  
Salam Azad ◽  
Ching-Pang Lee
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Low Mach Number ◽  
Heat Transfer Coefficients ◽  
Rotation Numbers ◽  
Wide Range ◽  
Mach Numbers

This paper experimentally investigates the effect of rotation on heat transfer in typical turbine blade serpentine coolant passage with ribbed walls at low Mach numbers. To achieve the low Mach number (around 0.01) condition, pressurized Freon R-134a vapor is utilized as the working fluid. The flow in the first passage is radial outward, after the 180 deg tip turn the flow is radial inward to the second passage, and after the 180 deg hub turn the flow is radial outward to the third passage. The effects of rotation on the heat transfer coefficients were investigated at rotation numbers up to 0.6 and Reynolds numbers from 30,000 to 70,000. Heat transfer coefficients were measured using the thermocouples-copper-plate-heater regional average method. Heat transfer results are obtained over a wide range of Reynolds numbers and rotation numbers. An increase in heat transfer rates due to rotation is observed in radially outward passes; a reduction in heat transfer rate is observed in the radially inward pass. Regional heat transfer coefficients are correlated with Reynolds numbers for nonrotation and with rotation numbers for rotating condition, respectively. The results can be useful for understanding real rotor blade coolant passage heat transfer under low Mach number, medium–high Reynolds number, and high rotation number conditions.

Heat Transfer in Rotating Multi-Pass Rectangular Smooth Channel With and Without a Turning Vane in Hub Region

2013 ◽  
Author(s):  
Jiang Lei ◽  
Shiou-Jiuan Li ◽  
Je-Chin Han ◽  
Luzeng Zhang ◽  
Hee-Koo Moon
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Reynolds Number ◽  
Density Ratio ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
The Third ◽  
Rotation Numbers ◽  
Smooth Channel ◽  
Turn Region

This paper experimentally investigates the effect of a turning vane on hub region heat transfer in a multi-pass rectangular smooth channel at high rotation numbers. The experimental data were taken in the second and the third passages (Aspect Ratio = 2:1) connected by an 180° U-bend. The flow was radial inward in the second passage and was radial outward after the 180° U-bend in the third passage. The Reynolds number ranged 10,000 to 40,000 while the rotation number ranged 0 to 0.42. The density ratio was a constant of 0.12. Results showed that rotation increases heat transfer on leading surface but decreases it on the trailing surface in the second passage. In the third passage, the effect of rotation is reversed. Without a turning vane, rotation reduces heat transfer substantially on all surfaces in the hub 180° turn region. After adding a half-circle-shaped turning vane, heat transfer coefficients do not change in the second passage (before turn) while they are quite different in the turn region and the third passage (after turn). Regional heat transfer coefficients are correlated with rotation numbers for multi-pass rectangular smooth channel with and without a turning vane.

Experimental Investigation on Staggered Impingement Heat Transfer on a Rib Roughened Plate With Different Crossflow Schemes

2010 ◽  
Author(s):  
Yunfei Xing ◽  
Bernhard Weigand
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Reynolds Numbers ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Plate Spacing ◽  
Air Jet ◽  
Impingement Heat Transfer ◽  
Rib Turbulators ◽  
Rib Roughened

A nine-by-nine staggered jet array impinging on a flat or rib roughened plate at Reynolds numbers from 15,000 to 35,000 has been studied by the transient liquid crystal method. The jet-to-plate spacings are adjusted to be 3, 4 and 5 jet diameters. Three jet-induced crossflow schemes, referred as minimum, medium and maximum crossflow correspondingly, have been measured. The local air jet temperature is measured at several positions on the impingement plate to account for an appropriate reference temperature of the heat transfer coefficient. The heat transfer results of the rib roughened plate are compared with those of the flat plate. The best heat transfer performance is obtained with the minimum crossflow and narrow jet-to-plate spacing no matter on a flat or roughened plate. The presence of rib turbulators on the target plate produce higher heat transfer coefficients than the flat plate for narrow jet-to-plate spacing by 7.5%. Note that this value is within the measurement uncertainty of 9%.

Heat Transfer in Rotating Serpentine Coolant Passage With Ribbed Walls at Low Mach Numbers

2013 ◽  
Author(s):  
Shang-Feng Yang ◽  
Je-Chin Han ◽  
Salam Azad ◽  
Ching-Pang Lee
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Low Mach Number ◽  
Heat Transfer Coefficients ◽  
Rotation Numbers ◽  
Wide Range ◽  
Mach Numbers

This paper experimentally investigates the effect of rotation on heat transfer in typical turbine blade serpentine coolant passage with ribbed walls at low Mach numbers. To achieve the low Mach number (around 0.01) condition, pressurized Freon R-134a vapor is utilized as the working fluid. The flow in the first passage is radial outward, after the 180° tip turn the flow is radial inward to the second passage, and after the 180° hub turn the flow is radial outward to the third passage. The effects of rotation on the heat transfer coefficients were investigated at rotation numbers up to 0.6 and Reynolds numbers from 30,000 to 70,000. Heat transfer coefficients were measured using the thermocouples-copper-plate-heater regional average method. Heat transfer results are obtained over a wide range of Reynolds numbers and rotation numbers. An increase in heat transfer rates due to rotation is observed in radially outward passes; a reduction in heat transfer rate is observed in the radially inward pass. Regional heat transfer coefficients are correlated with Reynolds numbers for non-rotation and with rotation numbers for rotating condition, respectively. The results can be useful for understanding real rotor blade coolant passage heat transfer under low Mach number, medium-high Reynolds number and high rotation number conditions.

Heat Transfer Measurements in Rotating Blade-Shape Serpentine Coolant Passage With Ribbed Walls at High Reynolds Numbers

2013 ◽  
Author(s):  
Akhilesh Rallabandi ◽  
Jiang Lei ◽  
Je-Chin Han ◽  
Salam Azad ◽  
Ching-Pang Lee
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Transfer Coefficients ◽  
Significant Deterioration ◽  
Turbine Cooling ◽  
Heat Transfer Coefficients ◽  
Experimental Heat ◽  
Rotation Numbers ◽  
High Reynolds

Flow in the internal three-pass serpentine rib turbulated passages of an advanced high pressure rotor blade is simulated on a 1:1 scale in the laboratory. Tests to measure the effect of rotation on the Nusselt number are conducted at rotation numbers up to 0.4 and Reynolds numbers from 75,000 to 165,000. To achieve this similitude, pressurized Freon R134a vapor is utilized as the working fluid. Experimental heat transfer coefficient measurements are made using the copperplate regional average method. Regional heat transfer coefficients are correlated with rotation numbers. An increase in heat transfer rates due to rotation is observed in radially outward passes; a reduction in heat transfer rate is observed in the radially inward pass. Strikingly, a significant deterioration in heat transfer is noticed in the “hub” region — between the radially inward second pass and the radially outward third pass. This heat transfer reduction is critical for turbine cooling designs.

Effect of Turbulator Width and Spacing on the Thermal Performance of Angled Ribs in a Rectangular Channel (AR = 3:1)

2008 ◽  
Author(s):  
Lesley M. Wright ◽  
Amir S. Gohardani
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Physical Distance ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Aspect Ratios ◽  
Rib Turbulators ◽  
Cooling Passage

The thermal performance is measured in a rectangular channel (AR = 3:1) with rib turbulators oriented at 45° to the mainstream flow. Ribs are placed on one of the wide walls, while heat transfer coefficients are also measured on a single smooth, narrow wall. The heat transfer enhancement is combined with the frictional losses to evaluate the benefit of turbulator width. Square ribs (w/e = 1) with a rib pitch–to–height (P/e) ratio of 8 serves as the baseline configuration. The rib width, w, is varied while the rib height, e, remains constant. Rib aspect ratios (w/e) of 1, 2, 3, and 4 are considered. In addition, the distance between the ribs is varied to consider the combined effect of rib width and rib spacing. As the width of the ribs is changing, the physical distance between the ribs, l, is varied, and four rib spacings are considered (l/e = 2.6, 6.6 [baseline corresponding to P/e = 8], 10.6, and 14.6). The thermal performance is measured in the 3:1 channel at Reynolds numbers of 10000, 30000, 50000, and 70000. Results indicate increasing the rib width is effective to increase the thermal performance of a cooling passage. However, the rib width and spacing must be varied in conjunction with one another to optimize the thermal performance.

scholarly journals Heat Transfer in Rotating Serpentine Passages With Trips Normal to the Flow

1992 ◽  
Vol 114 (4) ◽  
pp. 847-857 ◽  
Author(s):  
J. H. Wagner ◽  
B. V. Johnson ◽  
R. A. Graziani ◽  
F. C. Yeh
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Large Scale ◽  
Flow Direction ◽  
Operating Conditions ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Flow Equations ◽  
Turbine Blade Cooling ◽  
Heat Transfer Coefficients

Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large-scale, multipass, heat transfer model with both radially inward and outward flow. Trip strips on the leading and trailing surfaces of the radial coolant passages were used to produce the rough walls. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature ratio, Rossby number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges that are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from stationary and rotating similar models with trip strips. The heat transfer coefficients on surfaces, where the heat transfer increased with rotation and buoyancy, varied by as much as a factor of four. Maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels obtained with the smooth wall model. The heat transfer coefficients on surfaces where the heat transfer decreased with rotation, varied by as much as a factor of three due to rotation and buoyancy. It was concluded that both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips and that the effects of rotation were markedly different depending upon the flow direction.

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