Experimental and Computational Flow Field Studies of an Integrally Cast Cooling Manifold With and Without Rotation

2006 ◽  
Author(s):  
Ioannis Ieronymidis ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Robert Kingston
Keyword(s):  
Reynolds Number ◽  
Rotation Number ◽  
Discharge Coefficient ◽  
Thermal Contact ◽  
Leading Edge ◽  
Secondary Flows ◽  
Transfer Coefficients ◽  
Number Range ◽  
High Heat Transfer ◽  
Cooling Passage

This paper presents detailed pressure measurements and discharge coefficient data for a long, low aspect ratio manifold; part of a novel blade cooling scheme. The cooling geometry, in which a series of racetrack passages are connected to a central plenum, provides high heat transfer coefficients in regions of the blade in good thermal contact with the outer blade surface. The Reynolds number changes along its length because of the ejection of fluid through a series of 19 transfer holes in a staggered arrangement, which are used to connect ceramic cores during the casting process. For rotation number RN = 0 the velocity down each hole remains almost constant. A correlation between hole discharge coefficient and Velocity Head Ratio is also presented. Pressure loss coefficients in the passage and through the holes are also discussed. A High Pressure (HP) rig was tested to investigate compressibility effects and expand the inlet Reynolds number range. A CFD model was validated against the experimental data, and then used to investigate the effects of rotation on the hole discharge coefficients. Results are presented for an inlet Reynolds number of 43477. At an engine representative rotation number of 0.08 corresponding buoyancy number of 0.17 there was little effect of rotation. However, at high rotational speeds secondary flows in the cooling passage and the exit plenum greatly reduce the hole discharge coefficient by increasing the local cross flow at the hole entrances and capping the hole exits in a manner similar to that seen in leading edge film-cooling geometries.

Detailed Heat Transfer Measurements in a Model of an Integrally Cast Cooling Passage

2009 ◽  
Vol 132 (2) ◽  
Author(s):  
Ioannis Ieronymidis ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Robert Kingston
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Contact ◽  
Casting Process ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Cooling Passage

Detailed measurements of the heat transfer coefficient (htc) distributions on the internal surfaces of a novel gas turbine blade cooling configuration were carried out using a transient liquid crystal technique. The cooling geometry, in which a series of racetrack passages are connected to a central plenum, provides high heat transfer coefficients in regions of the blade in good thermal contact with the outer blade surface. The Reynolds number changes along its length because of the ejection of fluid through a series of 19 transfer holes in a staggered arrangement, which are used to connect ceramic cores during the casting process. Heat transfer coefficient distributions on these holes surface are particularly important in the prediction of blade life, as are heat transfer coefficients within the hole. The results at passage inlet Reynolds numbers of 21,667, 45,596, and 69,959 are presented along with in-hole htc distributions at Rehole=5930, 12,479, 19,147; and suction ratios of 0.98, 1.31, 2.08, and 18.67, respectively. All values are engine representative. Characteristic regions of high heat transfer downstream of the transfer holes were observed with enhancement of up to 92% over the Dittus–Boelter level. Within the transfer holes, the average htc level was strongly affected by the cross-flow at the hole entrance. htc levels were low in these short (l/d=1.5) holes fed from regions of developed boundary layer.

Heat Transfer in Trailing Edge, Wedge Shaped Cooling Channels With Slot Ejection Under High Rotation Numbers

2008 ◽  
Author(s):  
Yao-Hsien Liu ◽  
Michael Huh ◽  
Lesley M. Wright ◽  
Je-Chin Han
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Rotation Number ◽  
Cooling Channel ◽  
Transfer Coefficients ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Buoyancy Parameter ◽  
Narrow Side ◽  
Cooling Passage

Heat transfer coefficients are experimentally measured in a rotating cooling channel with slot ejection. This test section is used to model an internal cooling passage near the trailing edge of a gas turbine blade where the spent coolant exhausts through the slot to the mainstream flow. The regionally averaged heat transfer coefficients are measured in a wedge-shaped cooling channel (Dh = 2.22cm, Ac = 7.62cm2). Due to the discharging of coolant through the slots, the local mass flow rate decreases along the streamwise direction. The effect of slot ejection enhances the heat transfer near the narrow side of the channel, while heat transfer on the wide side decreases. The inlet Reynolds number of the coolant varies from 10000 to 40000 and the rotational speeds varies from 0 to 500 rpm. The inlet rotation number is from 0 – 1.0. The local rotation number and buoyancy parameter vary by the rotational speeds and the local Reynolds number in each region. The effect of rotation in this wedge-shaped channel with slot ejection is presented in this paper. This study shows that the rotation number and buoyancy parameter are good parameters to quantify the effect of rotation with slot ejection over the extended ranges achieved in this study.

Full-Field Flow Measurements and Heat Transfer of a Compact Jet Impingement Array With Local Extraction of Spent Fluid

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Andrew J. Onstad ◽  
Christopher J. Elkins ◽  
Robert J. Moffat ◽  
John K. Eaton
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Jet Impingement ◽  
Smooth Transition ◽  
Transfer Coefficients ◽  
Flow Measurements ◽  
Extraction Area ◽  
Number Range ◽  
Full Field ◽  
High Heat Transfer

Jet impingement cooling is widely used due to the very high heat transfer coefficients that are attainable. Both single and multiple jet systems can be used, however, multiple jet systems offer higher and more uniform heat transfer. A staggered array of 8.46 mm diameter impingement jets with jet-to-jet spacing of 2.34 D was examined where the spent fluid is extracted through one of six 7.36 mm diameter extraction holes regularly located around each jet. The array had an extraction area ratio (Ae/Ajet) of 2.23 locally and was tested with a jet-to-target spacing (H/D) of 1.18 jet diameters. Magnetic resonance velocimetry was used to both quantify and visualize the three dimensional flow field inside the cooling cavity at jet Reynolds numbers of 2600 and 5300. The spatially averaged velocity measurements showed a smooth transition is possible from the impingement jet to the extraction hole without the presence of large vortical structures. Mean Nusselt number measurements were made over a jet Reynolds number range of 2000–10,000. Nusselt numbers near 75 were measured at the highest Reynolds number with an estimated uncertainty of 7%. Large mass flow rate per unit heat transfer area ratios were required because of the small jet-to-jet spacing.

Heat Transfer in Rotating, Trailing Edge, Converging Channels With Smooth Walls and Pin-Fins

2020 ◽  
Author(s):  
Izzet Sahin ◽  
I-Lun Chen ◽  
Lesley M. Wright ◽  
Je-Chin Han ◽  
Hongzhou Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Rotation Number ◽  
Transfer Coefficients ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Pin Fins ◽  
Cooling Passage

Abstract The heat transfer and pressure drop characteristics of a rotating cooling channel that has an angled trapezoidal cross-section and converges from the hub to tip in both the streamwise and spanwise directions are experimentally investigated. The channel is oriented 120° with respect to the direction of rotation to model the geometry of an internal, trailing edge cooling passage. Both the leading and trailing sides of the channel are divided into three and six regions in the spanwise and streamwise directions, respectively. The copper plate method is used to obtain regionally averaged heat transfer coefficients. The pressure drop is measured utilizing pressure taps placed at the inlet and outlet of the channel. Experiments were conducted with the inlet Reynolds number ranging from 10,000 to 40,000. The rotational speed varies from 0 rpm to 300 rpm, resulting in the highest rotation number of 0.21. The effects of full pin-fins on the heat transfer and pressure drop characteristics are obtained and compared to the smooth surface converging channel results. The impact of the convergence, which causes variations of flow and geometric parameters through the passage, such as aspect ratio, Reynolds number, and rotation number, on the heat transfer coefficients and pressure drop are addressed. Results show that due to the 120° channel orientation, rotation has a positive impact on the leading and trailing surface heat transfer. Furthermore, the convergence decreases the aspect ratio while increasing Reynolds number. The convergence significantly enhances heat transfer on both the leading and trailing surfaces along the streamwise and spanwise directions. The convergence also reduces the rotation effect in the streamwise direction for a given mass flow rate.

Detailed Heat Transfer Measurements in a Model of an Integrally Cast Cooling Passage

2006 ◽  
Author(s):  
Ioannis Ieronymidis ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Robert Kingston
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Thermal Contact ◽  
Casting Process ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Cooling Passage

Detailed measurements of the heat transfer coefficient distributions on the internal surfaces of a novel gas turbine blade cooling configuration were carried out using a transient liquid crystal technique. The cooling geometry, in which a series of racetrack passages are connected to a central plenum, provides high heat transfer coefficients in regions of the blade in good thermal contact with the outer blade surface. The Reynolds number changes along its length because of the ejection of fluid through a series of 19 transfer holes in a staggered arrangement, which are used to connect ceramic cores during the casting process. Heat transfer coefficient distributions on this holes surface are particularly important in the prediction of blade life, as are heat transfer coefficients within the hole. Results at passage inlet Reynolds numbers of 21667, 45596 and 69959 are presented along with in-hole htc distributions at Rehole = 5930, 12479, 19147 and suction ratios of 0.98, 1.31, 2.08, 18.67. All values are engine representative. The results were compared to predictions made using the commercial CFD package Fluent. Characteristic regions of high heat transfer downstream of the transfer holes were observed with enhancement of up to 92% over the Dittus-Boelter level. Within the transfer holes, the average htc level was strongly affected by the crossflow at the hole entrance. Htc levels were low in these short (l/d = 1.5) holes fed from regions of developed boundary layer.

Heat Transfer in Rotating, Trailing-Edge, Converging Channels With Smooth Walls and Pin-Fins

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Izzet Sahin ◽  
I-Lun Chen ◽  
Lesley M. Wright ◽  
Je-Chin Han ◽  
Hongzhou Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Rotation Number ◽  
Transfer Coefficients ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Pin Fins ◽  
Cooling Passage

Abstract The heat transfer and pressure drop characteristics of a rotating cooling channel that has an angled trapezoidal cross section and converges from the hub to the tip in both the streamwise and spanwise directions are experimentally investigated. The channel is oriented 120 deg with respect to the direction of rotation to model the geometry of an internal, trailing-edge cooling passage. Both the leading and trailing sides of the channel are divided into three and six regions in the spanwise and streamwise directions, respectively. The copper plate method is used to obtain regionally averaged heat transfer coefficients. The pressure drop is measured using pressure taps placed at the inlet and outlet of the channel. Experiments were conducted with the inlet Reynolds number ranging from 10,000 to 40,000. The rotational speed varies from 0 rpm to 300 rpm, resulting in the highest rotation number of 0.21. The effects of full pin-fins on the heat transfer and pressure drop characteristics are obtained and compared to the smooth surface converging channel results. The impact of the convergence, which causes variations of flow and geometric parameters through the passage, such as aspect ratio, Reynolds number, and rotation number, on the heat transfer coefficients and pressure drop are addressed. Results show that due to the 120 deg channel orientation, the rotation has a positive impact on the leading and trailing surface heat transfer. Furthermore, the convergence decreases the aspect ratio while increasing the Reynolds number. The convergence significantly enhances heat transfer on both the leading and trailing surfaces along the streamwise and spanwise directions. The convergence also reduces the rotation effect in the streamwise direction for a given mass flow rate.

Heat Transfer and Flowfield Measurements in the Leading Edge Region of a Stator Vane Endwall

1999 ◽  
Vol 121 (3) ◽  
pp. 558-568 ◽  
Author(s):  
M. B. Kang ◽  
A. Kohli ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Secondary Flows ◽  
Edge Region ◽  
Leading Edge Vortex ◽  
Stator Vane ◽  
Edge Vortex ◽  
The Mean

The leading edge region of a first-stage stator vane experiences high heat transfer rates, especially near the endwall, making it very important to get a better understanding of the formation of the leading edge vortex. In order to improve numerical predictions of the complex endwall flow, benchmark quality experimental data are required. To this purpose, this study documents the endwall heat transfer and static pressure coefficient distribution of a modern stator vane for two different exit Reynolds numbers (Reex = 6 × 105 and 1.2 × 106). In addition, laser-Doppler velocimeter measurements of all three components of the mean and fluctuating velocities are presented for a plane in the leading edge region. Results indicate that the endwall heat transfer, pressure distribution, and flowfield characteristics change with Reynolds number. The endwall pressure distributions show that lower pressure coefficients occur at higher Reynolds numbers due to secondary flows. The stronger secondary flows cause enhanced heat transfer near the trailing edge of the vane at the higher Reynolds number. On the other hand, the mean velocity, turbulent kinetic energy, and vorticity results indicate that leading edge vortex is stronger and more turbulent at the lower Reynolds number. The Reynolds number also has an effect on the location of the separation point, which moves closer to the stator vane at lower Reynolds numbers.

scholarly journals Highly Resolved Distribution of Heat Transfer for Turbine Leading Edge Film Cooling Including Reynolds Number and Blowing Rate Effects

1998 ◽  
Author(s):  
K. Jung ◽  
D. K. Hennecke
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Heat Mass Transfer ◽  
Leading Edge ◽  
Transfer Coefficients ◽  
Complex Flow ◽  
Long Distance ◽  
Naphthalene Sublimation Technique

The effect of leading edge film cooling on heat transfer was experimentally investigated using the naphthalene sublimation technique. The experiments were performed on a symmetrical model of the leading edge suction side region of a high pressure turbine blade with one row of film cooling holes on each side. Two different lateral inclinations of the injection holes were studied: 0° and 45°. In order to build a data base for the validation and improvement of numerical computations, highly resolved distributions of the heat/mass transfer coefficients were measured. Reynolds numbers (based on hole diameter) were varied from 4000 to 8000 and blowing rate from 0.0 to 1.5. For better interpretation, the results were compared with injection-flow visualizations. Increasing the blowing rate causes more interaction between the jets and the mainstream, which creates higher jet turbulence at the exit of the holes resulting in a higher relative heat transfer. This increase remains constant over quite a long distance dependent on the Reynolds number. Increasing the Reynolds number keeps the jets closer to the wall resulting in higher relative heat transfer. The highly resolved heat/mass transfer distribution shows the influence of the complex flow field in the near hole region on the heat transfer values along the surface.

Heat Transfer in a Rotating Two-Pass Rectangular Channel Featuring Reduced Cross-Sectional Area After Tip Turn (Aspect Ratio = 4:1 to 2:1) With Profiled 60 deg Angled Ribs

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Andrew F Chen ◽  
Chao-Cheng Shiau ◽  
Je-Chin Han ◽  
Robert Krewinkel
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Flow Direction ◽  
Rectangular Channel ◽  
Secondary Flows ◽  
Transfer Coefficients ◽  
First Passage ◽  
Cross Sectional ◽  
Internal Surfaces

The present study features a two-pass rectangular channel with an aspect ratio (AR) = 4:1 in the first pass and an AR = 2:1 in the second pass after a 180-deg tip turn. In addition to the smooth-wall case, ribs with a profiled cross section are placed at 60 deg to the flow direction on both the leading and trailing surfaces in both passages (P/e = 10, e/Dh ∼ 0.11, parallel and in-line). Regionally averaged heat transfer measurement method was used to obtain the heat transfer coefficients on all internal surfaces. The Reynolds number (Re) ranges from 10,000 to 70,000 in the first passage, and the rotational speed ranges from 0 to 400 rpm. Under pressurized condition (570 kPa), the highest rotation number achieved was Ro = 0.39 in the first passage and 0.16 in the second passage. The results showed that the turn-induced secondary flows are reduced in an accelerating flow. The effects of rotation on heat transfer are generally weakened in the ribbed case than the smooth case. Significant heat transfer reduction (∼30%) on the tip wall was seen in both the smooth and ribbed cases under rotating condition. Overall pressure penalty was reduced for the ribbed case under rotation. Reynolds number effect was found noticeable in the current study. The heat transfer and pressure drop characteristics are sensitive to the geometrical design of the channel and should be taken into account in the design process.

Experimental Results of Flow Nozzle Based on PTC 6 for High Reynolds Number

2014 ◽  
Author(s):  
Noriyuki Furuichi ◽  
Kar-Hooi Cheong ◽  
Yoshiya Terao ◽  
Shinichi Nakao ◽  
Keiji Fujita ◽  
...  
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Discharge Coefficient ◽  
Experimental Results ◽  
Flow Conditions ◽  
Number Range ◽  
Discharge Coefficients ◽  
Reynolds Number Range ◽  
Lower Reynolds Number ◽  
High Reynolds

Discharge coefficients for three flow nozzles based on ASME PTC 6 are measured under many flow conditions at AIST, NMIJ and PTB. The uncertainty of the measurements is from 0.04% to 0.1% and the Reynolds number range is from 1.3×105 to 1.4×107. The discharge coefficients obtained by these experiments is not exactly consistent to one given by PTC 6 for all examined Reynolds number range. The discharge coefficient is influenced by the size of tap diameter even if at the lower Reynolds number region. Experimental results for the tap of 5 mm and 6 mm diameter do not satisfy the requirements based on the validation procedures and the criteria given by PTC 6. The limit of the size of tap diameter determined in PTC 6 is inconsistent with the validation check procedures of the calibration result. An enhanced methodology including the term of the tap diameter is recommended. Otherwise, it is recommended that the calibration test should be performed at as high Reynolds number as possible and the size of tap diameter is desirable to be as small as possible to obtain the discharge coefficient with high accuracy.

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