Heat Transfer in High-Speed Rotating Trapezoidal Duct With Rib-Roughened Surfaces and Air Bleeds From the Wall on the Apical Side

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Minn Liou ◽  
Shyr Fuu Chiou ◽  
Shuen Fei Chang
Keyword(s):  
Heat Transfer ◽  
High Speed ◽  
Density Ratio ◽  
Side Wall ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbine Rotor ◽  
Practical Applications ◽  
Apical Side ◽  
Rib Roughened

An experimental study of heat transfer in a radially rotating trapezoidal duct with two opposite walls roughened by 45deg staggered ribs and bleed from the apical side wall is performed. Centerline heat transfer variations on two rib-roughened surfaces are measured for radially outward flows with and without bleeds at test conditions of Reynolds number (Re), rotation number (Ro), and density ratio (Δρ∕ρ) in the ranges of 15,000–30,000, 0–0.8, and 0.04–0.31, respectively. Geometrical configurations and rotation numbers tested have considerably extended the previous experiences that offer practical applications to the trailing edge cooling of a gas turbine rotor blade. A selection of experimental data illustrates the individual and interactive influences of Re, Ro, and buoyancy number (Bu) on local heat transfer with and without bleeds. Local heat transfer results are generated with the influences of bleeds on the apical side examined to establish heat transfer correlations with Re, Ro, and Bu as the controlling flow parameters for design applications. The rotation of present trapezoidal duct with rib-roughened surfaces and air bleeds on the apical side worsens the impairing heat transfer impacts due to bleeds. Within the Ro range of 0.1–0.8, bleeds on the apical side of the rotating channel respectively produce 25–50% and 25–40% of heat transfer reductions from the rotational no-bleed references along the leading and trailing centerlines. Such heat transfer reductions due to the combined bleeds and Ro-Bu impacts need design precautions for turbine rotor blades.

High Rotation Number Heat Transfer of Rotating Trapezoidal Duct With 45-deg Staggered Ribs and Bleeds From Apical Side Wall

2007 ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Minn Liou ◽  
Shyr Fuu Chiou ◽  
Shuen Fei Chang
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Density Ratio ◽  
Side Wall ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbine Rotor ◽  
Practical Applications ◽  
Turbine Rotor Blade ◽  
Apical Side

An experimental study of heat transfer in a radially rotating trapezoidal duct with two opposite walls roughened by 45° staggered ribs and mid-rib bleeds from the apical side wall is performed. Centerline heat transfer variations on two rib-roughened surfaces are measured for radially outward flows with and without bleeds at test conditions of Reynolds number (Re), rotation number (Ro) and density ratio (Δρ/ρ) in the ranges of 15000–30000, 0–0.8 and 0.04–0.31, respectively. Geometrical configurations and rotation numbers tested have considerably extended the previous experiences that offer practical applications to the trail edge cooling of a gas turbine rotor blade. A selection of experimental data illustrates the individual and interactive influences of Re, Ro and buoyancy number (Bu) on local heat transfer with and without bleeds. Local heat transfer results are generated with the influences of sidewall bleeds examined to establish heat transfer correlations with Re, Ro and Bu as the controlling flow parameters for design applications.

Heat Transfer in a Radially Rotating Square-Sectioned Duct With Two Opposite Walls Roughened by 45Deg Staggered Ribs at High Rotation Numbers

2006 ◽  
Vol 129 (2) ◽  
pp. 188-199 ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Minn Liou ◽  
Jui-Hung Hung ◽  
Wen-Hsien Yeh
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Coriolis Force ◽  
Density Ratio ◽  
Inertial Force ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Test Channel ◽  
Rib Roughened

This paper describes an experimental study of heat transfer in a radially rotating square duct with two opposite walls roughened by 45deg staggered ribs. Air coolant flows radially outward in the test channel with experiments to be undertaken that match the actual engine conditions. Laboratory-scale heat transfer measurements along centerlines of two rib-roughened surfaces are performed with Reynolds number (Re), rotation number (Ro), and density ratio (Δρ∕ρ) in the ranges of 7500–15,000, 0–1.8, and 0.076–0.294. The experimental rig permits the heat transfer study with the rotation number considerably higher than those studied in other researches to date. The rotational influences on cooling performance of the rib-roughened channel due to Coriolis forces and rotating buoyancy are studied. A selection of experimental data illustrates the individual and interactive impacts of Re, Ro, and buoyancy number on local heat transfer. A number of experimental-based observations reveal that the Coriolis force and rotating buoyancy interact to modify heat transfer even if the rib induced secondary flows persist in the rotating channel. Local heat transfer ratios between rotating and static channels along the centerlines of stable and unstable rib-roughened surfaces with Ro varying from 0.1 to 1.8 are in the ranges of 0.6–1.6 and 1–2.2, respectively. Empirical correlations for periodic flow regions are developed to permit the evaluation of interactive and individual effects of ribflows, convective inertial force, Coriolis force, and rotating buoyancy on heat transfer.

Heat Transfer in a Radially Rotating Square-Sectioned Duct With Two Opposite Walls Roughened by 45° Staggered Ribs

2006 ◽  
Author(s):  
Shyy Woei Chang ◽  
Tong-Minn Liou ◽  
Wen-Hsien Yeh ◽  
Jui-Hung Hung
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Coriolis Force ◽  
Density Ratio ◽  
Inertial Force ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Test Channel ◽  
Rib Roughened

This paper describes an experimental study of heat transfer in a radially rotating square duct with two opposite walls roughened by 45° staggered ribs. Air coolant flows radially outward in the test channel with experiments to be undertaken that match the actual engine conditions. Laboratory-scale heat transfer measurements along centerlines of two rib-roughened surfaces are performed with Reynolds number (Re), rotation number (Ro) and density ratio (Δρ/ρ) in the ranges of 7500–15000, 0–1.8 and 0.076–0.294. The experimental rig permits the heat transfer study with the rotation number considerably higher than those studied in other researches to date. The rotational influences on cooling performance of the rib-roughened channel due to Coriolis forces and rotating buoyancy are studied. A selection of experimental data illustrates the individual and interactive impacts of Re, Ro and buoyancy number on local heat transfer. A number of experimental-based observations reveal that the Coriolis force and rotating buoyancy interact to modify heat transfer even if the rib induced secondary flows persist in the rotating channel. Local heat transfer ratios between rotating and static channels along the centerlines of stable and unstable rib-roughened surfaces with Ro varying from 0.1 to 1.8 are in the ranges of 0.6–1.6 and 1–2.2 respectively. Empirical correlations for periodic flow regions are developed to permit the evaluation of interactive and individual effects of rib-flows, convective inertial force, Coriolis force and rotating buoyancy on heat transfer.

Local Heat Transfer Distribution in a Rotating Serpentine Rib-Roughened Flow Passage

1993 ◽  
Vol 115 (3) ◽  
pp. 560-567 ◽  
Author(s):  
N. Zhang ◽  
J. Chiou ◽  
S. Fann ◽  
W.-J. Yang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Performance ◽  
Height Ratio ◽  
Nusselt Numbers ◽  
Rayleigh Numbers ◽  
Rib Roughened

Experiments are performed to determine the local heat transfer performance in a rotating serpentine passage with rib-roughened surfaces. The ribs are placed on the trailing and leading walls in a corresponding posited arrangement with an angle of attack of 90 deg. The rib height-to-hydraulic diameter ratio, e/Dh, is 0.0787 and the rib pitch-to-height ratio, s/e, is 11. The throughflow Reynolds number is varied, typically at 23,000, 47,000, and 70,000 in the passage both at rest and in rotation. In the rotation cases, the rotation number is varied from 0.023 to 0.0594. Results for the rib-roughened serpentine passages are compared with those of smooth ones in the literature. Comparison is also made on results for the rib-roughened passages between the stationary and rotating cases. It is disclosed that a significant enhancement is achieved in the heat transfer in both the stationary and rotating cases resulting from an installation of the ribs. Both the rotation and Rayleigh numbers play important roles in the heat transfer performance on both the trailing and leading walls. Although the Reynolds number strongly influences the Nusselt numbers in the rib-roughened passage of both the stationary and rotating cases, Nuo and Nu, respectively, it has little effect on their ratio Nu/Nuo.

Effects of Rib Arrangements on Pressure Drop and Heat Transfer in a Rib-Roughened Channel With a Sharp 180 deg Turn

1997 ◽  
Vol 119 (3) ◽  
pp. 610-616 ◽  
Author(s):  
S. Mochizuki ◽  
A. Murata ◽  
M. Fukunaga
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Secondary Flow ◽  
Flow Direction ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Diameter Ratio ◽  
Equivalent Diameter ◽  
Before And After ◽  
Rib Roughened

The objective of this study was to investigate, through experiments, the combined effects of a sharp 180 deg turn and rib patterns on the pressure drop performance and distributions of the local heat transfer coefficient in an entire two-pass rib-roughened channel with a 180 deg turn. The rib pitch-to-equivalent diameter ratio P/de was 1.0, the rib-height-to-equivalent diameter ratio e/de was 0.09, and the rib angle relative to the main flow direction was varied from 30 ∼ 90 deg with an interval of 15 deg. Experiments were conducted for Reynolds numbers in the range 4000 ∼ 30,000. It was disclosed that, due to the interactions between the bend-induced secondary flow and the rib-induced secondary flow, the combination of rib patterns in the channel before and after the turn causes considerable differences in the pressure drop and heat transfer performance of the entire channel.

scholarly journals Tip Leakage Flow in a Linear Turbine Cascade

1988 ◽  
Vol 110 (1) ◽  
pp. 18-26 ◽  
Author(s):  
J. Moore ◽  
J. S. Tilton
Keyword(s):  
Heat Transfer ◽  
Potential Flow ◽  
Pressure Rise ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Tip Clearance ◽  
Tip Leakage Flow ◽  
Vena Contracta

An experimental and analytical study of flow in the tip clearance gap of a linear turbine rotor blade cascade has been performed. Measurements of wall static pressures and flow velocities are used to verify a flow model involving a vena contracta, near the tip gap entrance, followed by flow mixing to fill the gap. A frequently referenced potential flow theory for flow into a tip gap is found to be in error and the correct theory is shown to model the unloading along the pressure surface of the blade and the endwall static pressure distribution up to the vena contracta accurately. A combined potential flow and mixing model accounts for the pressure rise in the tip gap due to mixing. Turbine tip heat transfer is also discussed and a correlation of local heat transfer rates for essentially incompressible flow over unshrouded turbine rotor blades is presented.

Aero-Thermal Performance of a Winglet at Engine Representative Mach and Reynolds Numbers

2010 ◽  
Author(s):  
D. O. O’Dowd ◽  
Q. Zhang ◽  
L. He ◽  
M. L. G. Oldfield ◽  
P. M. Ligrani ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Shock Wave ◽  
Thermal Performance ◽  
High Speed ◽  
Local Heat Transfer ◽  
Wave Structure ◽  
Local Heat ◽  
Test Facility ◽  
Shock Wave Structure ◽  
Spatially Resolved

This paper presents an experimental and numerical investigation of the aero-thermal performance of an uncooled winglet tip, under transonic conditions. Spatially-resolved heat transfer data, including winglet tip surface and near tip side walls, are obtained using the transient infrared thermography technique within the Oxford High Speed Linear Cascade test facility. CFD predictions are also conducted using the Rolls-Royce HYDRA suite. Most of the spatial heat transfer variations on the tip surface are well-captured by the CFD solver. The transonic flow pattern and its influence on heat transfer are analyzed, which shows that the turbine blade tip heat transfer is greatly influenced by the shock wave structure inside the tip gap. The effect of the casing relative motion is also numerically investigated. The CFD results indicate that the local heat transfer distribution on the tip is affected by the relative casing motion, but the tip flow choking and shock wave structure within the tip gap still exist in the aft region of the blade.

Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel

2012 ◽  
Vol 135 (2) ◽  
Author(s):  
Sin Chien Siw ◽  
Minking K. Chyu ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Hybrid Technique ◽  
Pin Fins ◽  
Cooling Passage ◽  
Rib Roughened

An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened channel combined with detached pin-fins. The overall channel geometry (W = 76.2 mm, E = 25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D = 6.35 mm = [1/4]E, three different pin-fin height-to-diameter ratios, H/D = 4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e., C/D = 0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross ribs, namely the broken rib and full rib are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin-fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all pin elements. The presence of ribs enhances local heat transfer coefficient on the endwall substantially by approximately 20% to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperform cases with broken ribs or full ribs.

Effects of Pin Detached Space on Heat Transfer in a Rib Roughened Channel

2011 ◽  
Author(s):  
Sin Chien Siw ◽  
Minking K. Chyu ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Hybrid Technique ◽  
Pin Fins ◽  
Cooling Passage ◽  
Rib Roughened

An experimental study is performed to investigate the heat transfer characteristics and frictional losses in a rib roughened walls combined with detached pin-fins. The overall channel geometry (W = 76.2 mm, E = 25.4 mm) simulates an internal cooling passage of wide aspect ratio (3:1) in a gas turbine airfoil. With a given pin diameter, D = 6.35 mm = 1/4E, three different pin-fin height-to-diameter ratios, H/D = 4, 3, and 2, were examined. Each of these three cases corresponds to a specific pin array geometry of detachment spacing (C) between the pin-tip and one of the endwalls, i.e. C/D = 0, 1, 2, respectively. The rib height-to-channel height ratio is 0.0625. Two newly proposed cross-ribs, namely the broken ribs and full ribs are evaluated in this effort. The broken ribs are positioned in between two consecutive rows of pin-fins, while the full ribs are fully extended adjacent to the pin fins. The Reynolds number, based on the hydraulic diameter of the unobstructed cross-section and the mean bulk velocity, ranges from 10,000 to 25,000. The experiment employs a hybrid technique based on transient liquid crystal imaging to obtain distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all the pin elements. The presence of ribs has enhanced the local heat transfer coefficient on the endwall substantially by about 20% up to 50% as compared to the neighboring endwall. In addition, affected by the rib geometry, which is a relatively low profile as compared to the overall height of the channel, the pressure loss seems to be insensitive to the presence of the ribs. However, from the overall heat transfer enhancement standpoint, the baseline cases (without ribs) outperforms cases with broken ribs and full ribs.

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