scholarly journals Heat transfer in an impingement cooling channel under isothermal boundaries at high rotation numbers

2022 ◽  
Vol 182 ◽  
pp. 121940
Author(s):  
Hongwu Deng ◽  
Hua Li ◽  
Jinglei Xu
Keyword(s):  
Heat Transfer ◽  
Cooling Channel ◽  
Impingement Cooling ◽  
Rotation Numbers

Heat Transfer in a Rotating, Two-Pass, Variable Aspect Ratio Cooling Channel With Profiled V-Shaped Ribs

2020 ◽  
Author(s):  
I-Lun Chen ◽  
Izzet Sahin ◽  
Lesley M. Wright ◽  
Je-Chin Han ◽  
Robert Krewinkel
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Channel Modeling ◽  
Cooling Channel ◽  
Transfer Enhancement ◽  
Rotation Numbers ◽  
First Pass ◽  
Rib Turbulators

Abstract The thermal performance of two V-type rib configurations is measured in a rotating, two-pass cooling channel. Modeling modern, high pressure, turbine blades, the cross-section of the cooling channel varies from the first pass to the second pass. The coolant travels radially outward in the rectangular first pass with an aspect ratio of 4:1. Near the tip region, the coolant turns 180°, and travels radially inward in a 2:1 rectangular channel. The serpentine passage is positioned such that both the first and second passes are oriented 90° to the direction of rotation. The leading and trailing surfaces of both the first and second pass of the channel are roughened with V-type rib turbulators. The thermal performance of two V-type configurations is measured in this two-pass channel. The first V-shaped configuration is similar to a traditional V-shaped turbulator with a narrow gap at the apex of the V. The configuration is modified by off-setting one leg of the V to create a staggered discrete, V-shaped configuration. The ribs are oriented 45° relative to the streamwise coolant direction. In both passes, the rib spacing is P/e = 10 and the rib height – to – channel height is e/H = 0.16. The heat transfer enhancement and frictional losses are measured for both rib configurations with varying Reynolds and rotation numbers. The Reynolds number varies from 10,000 to 45,000 in the AR = 4:1 first pass; this corresponds to 16,000 to 73,500 in the AR = 2:1 second pass. Considering the effect of rotation, the rotational speed of the channel varies from 0–400 rpm with maximum rotation numbers of 0.39 and 0.16 in the first and second passes, respectively. The heat transfer enhancement on both the leading and trailing surfaces of the first pass of the 45° V-shaped channel is slightly reduced with rotation. In the second pass, the heat transfer increases on the leading surface while it decreases on the trailing surface. The 45° staggered, discrete V-shaped ribs provide increased heat transfer and thermal performance compared to the traditional V-shaped and standard, 45° angled rib turbulators.

HEAT TRANSFER IN A ROTATING, TWO-PASS, VARIABLE ASPECT RATIO COOLING CHANNEL WITH PROFILED V-SHAPED RIBS

2021 ◽  
pp. 1-45
Author(s):  
I-Lun Chen ◽  
Izzet Sahin ◽  
Lesley Wright ◽  
Je-Chin Han ◽  
Robert Krewinkel
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Cooling Channel ◽  
Narrow Gap ◽  
Transfer Enhancement ◽  
Rotation Numbers ◽  
First Pass ◽  
Rib Turbulators

Abstract The thermal performance of two V-type rib configurations is measured in a rotating, two-pass cooling channel. The coolant travels radially outward in the rectangular first pass (AR = 4:1), and travels radially inward in the second pass (AR = 2:1). Both the passages are oriented 90° to the direction of rotation. The LS and TS of the channel are roughened with V-type ribs. The first V-shaped configuration has a narrow gap at the apex of the V. The configuration is modified by off-setting one leg of the V to create a staggered discrete, V-shaped configuration. The ribs are oriented 45° relative to the streamwise coolant direction. The heat transfer enhancement and frictional losses are measured with varying Reynolds and rotation numbers. The Reynolds number varies from 10,000 to 45,000 in the AR = 4:1 first pass; this corresponds to 16,000 to 73,500 in the AR = 2:1 second pass. The maximum rotation numbers are 0.39 and 0.16 in the first and second passes, respectively. The heat transfer enhancement on both the leading and trailing surfaces of the first pass of the 45° V-shaped channel is slightly reduced with rotation. In the second pass, the heat transfer increases on the leading surface while it decreases on the trailing surface. The 45° staggered, discrete V-shaped ribs provide increased heat transfer and thermal performance compared to the traditional V-shaped and standard, 45° angled rib turbulators.

scholarly journals Effect of Rotation and Hole Arrangement in Cold Bridge-Type Impingement Cooling Systems

2019 ◽  
Vol 4 (2) ◽  
pp. 13 ◽  
Author(s):  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Impingement Cooling ◽  
Complex Interactions ◽  
Supply Condition ◽  
Rotation Numbers ◽  
Supply Channel ◽  
Bridge Type

Experimental activity has been performed to study different impingement cooling schemes in static and rotating conditions. Geometry replicates a leading-edge cold bridge system, including a radial supply channel and five rows of film-cooling and showerhead holes. Two impingement geometries have been studied, with different numbers of holes and diameters but with equal overall passage area. Reynolds numbers up to 13,800 and rotation numbers up to 0.002 have been investigated (based on an equivalent slot width). Tests have been performed using a novel implementation of transient heat transfer technique, which allows correct replication of the sign of buoyancy forces by flowing ambient temperature air into a preheated test article. Results show that complex interactions occur between the different features of the system, with a particularly strong effect of jet supply condition. Rotation further interacts with these phenomena, generally leading to a slight decrease in heat transfer.

Application and Design of Multi-Impingement Cooling Channel in Turbine Blade Trail Edge

2020 ◽  
Vol 37 (3) ◽  
pp. 241-256
Author(s):  
Longfei Wang ◽  
Fengbo Wen ◽  
Songtao Wang ◽  
Xun Zhou ◽  
Zhongqi Wang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Impinging Jet ◽  
Surface Heat ◽  
Cooling Channel ◽  
Plate Surface ◽  
Impingement Cooling ◽  
Surface Heat Transfer ◽  
Pin Fins

AbstractThe numerical simulations are used to conduct the comparative study of pin-fins cooling channel and multi-impingement cooling channel on the heat transfer and flow, and to design the multi-impingement channel through the parameters of impinging distance and impingement-jet-plate thickness. The Reynolds number ranges from 1e4 to 6e4. The dimensionless impinging distance is 0.60, 1.68, 2.76, respectively, and the dimensionless impinging-jet-thickness is 0.5, 1.0, 1.5, respectively. The endwall surface, pin-fins surface, impinging-jet-plate surface are the three object surfaces to investigate the channel heat transfer performance. The heat transfer coefficient $h$ and augmentation factor $Nu/N{u_0}$ are selected to measure the surface heat transfer, and the friction coefficient $f$ is chosen to evaluate the channel flow characteristics. The impinging-jet-plate surface owns higher heat transfer coefficient and larger area than pin-fins surface, which are the main reasons to improve the heat transfer performance of multi-impingement cooling channel. Reducing the impinging distance can improve the endwall surface heat transfer obviously and enhance impingement plate surface heat transfer to some extent, decreasing the thickness of impinging-jet-plate can significantly increase its own heat transfer coefficient, which both all increase the cooling air flow loss.

High Rotation Number Effect on Heat Transfer in a Leading Edge Cooling Channel With Three Channel Orientations

2012 ◽  
Author(s):  
Szu-Chi Huang ◽  
Yao-Hsien Liu
Keyword(s):  
Heat Transfer ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Cooling Channel ◽  
Height Ratio ◽  
Triangular Channel ◽  
Rotation Numbers ◽  
Channel Orientation

Heat transfer in a leading edge, triangular shaped cooling channel with three channel orientations under high rotation numbers is experimentally studied. Continuous ribs and V-shaped ribs, both at 45° rib angle of attack, are applied on the leading and trailing surfaces. For each rib case, three channel orientations (90°, 67.5°, and 45°) with respect to the plane of rotation are tested. The rib height to hydraulic diameter ratio (e/Dh) is 0.085 and the rib pitch to height ratio (P/e) is 9. Reynolds numbers are from 15000 to 25000, and the rotation numbers are from 0 to 0.65. Results show that the heat transfer variation is influenced by the combined effects of rib configuration and channel orientation. Effect of channel orientation influences local heat transfer distribution inside this triangular channel, and heat transfer is enhanced gradually on the leading surface when the channel orientation varies from 90° to 45° for both ribbed cases in this study.

High Rotation Number Effect on Heat Transfer in a Leading Edge Cooling Channel of Gas Turbine Blades With Three Channel Orientations

2013 ◽  
Vol 5 (4) ◽  
Author(s):  
Szu-Chi Huang ◽  
Yao-Hsien Liu
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Turbine Blades ◽  
Leading Edge ◽  
Cooling Channel ◽  
Number Range ◽  
Gas Turbine Blades ◽  
Rotation Numbers ◽  
Mainstream Flow ◽  
Channel Orientation

Heat transfer in a leading edge, triangular-shaped cooling channel with three channel orientations under high rotation numbers is investigated in this study. Continuous ribs and V-shaped ribs (P/e = 9, e/Dh = 0.085), both placed at an angle (α = 45 deg) to the mainstream flow, are applied on the leading and trailing surfaces. The Reynolds number range is 15,000–25,000 and the rotation number range is 0–0.65. Effects of high rotation number on heat transfer with three angles of rotation (90 deg, 67.5 deg, and 45 deg) are tested. Results show that heat transfer is influenced by the combined effects of rib and channel orientation. When the rotation number is smaller than 0.4, rotation causes a decrease in the average Nusselt number ratios on the leading surface at a channel orientation of 90 deg. Heat transfer is enhanced gradually on the leading surface when the channel orientation varies from 90 deg to 45 deg for both ribbed cases. The highest heat transfer enhancement due to rotation is found at the highest rotation number of 0.65.

Effects of Turning Angle and Turning Internal Radius on Channel Impingement Cooling for a Novel Internal Cooling Structure

2020 ◽  
Author(s):  
Wei He ◽  
Qinghua Deng ◽  
Guoying Yang ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Loss ◽  
Leading Edge ◽  
Geometrical Parameters ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Turning Angle ◽  
Impingement Cooling ◽  
Internal Radius

Abstract Leading edge multi-channel double wall design, a novel internal cooling structure, has been put forward recently to enable higher overall cooling effectiveness with less penalty of coolant mass flow and pressure loss. Our previous work has proved the advantages of the design under operating condition relative to conventional internal cooling methods including impingement cooling and swirl cooling. Channel impingement cooling structure, which is utilized at the turning region of the leading edge, is the critical factor to realize the high cooling performance of the design. Hence, the turning angle and turning internal radius of the cooling channel are two key parameters for the novel design, and this paper focuses on the effects of these two parameters on the flow and heat transfer characteristics of the channel impingement cooling structure. Nine simplified single-channel models with different turning angles (45°, 60°, and 75°) and radiuses (0.6 mm, 0.9 mm, and 1.2 mm) were adopted to conduct the study, and the jet Reynolds number ranges from 10,000 to 40,000. The results show that the turning angle and turning internal radius affect the jet form significantly for the same mechanism. Small turning angle means large impingement, which leads to stream-wise counter-rotational vortices and high turbulence intensity, but increasing turning internal radius transfers the jet form from impingement jet to laminar layer attaching the target surface with low heat transfer. The turning internal radius has stronger effect than turning angle. With higher jet Reynolds number, both the heat transfer and total pressure loss increase dramatically, and the effects of geometrical parameters are clearer.

Effects of Turning Angle and Turning Internal Radius on Channel Impingement Cooling for a Novel Internal Cooling Structure

2021 ◽  
pp. 1-43
Author(s):  
Wei He ◽  
Qinghua Deng ◽  
Gouying Yang ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Loss ◽  
Single Channel ◽  
Geometrical Parameters ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Turning Angle ◽  
Impingement Cooling ◽  
Internal Radius

Abstract Recently, a novel internal cooling structure, namely multi-channel wall, has been put forward to enable higher overall cooling effectiveness with less coolant and pressure loss. Our previous work has proved the advantages of the design relative to conventional impingement cooling and swirl cooling. Channel impingement cooling structure, which is utilized at the turning region of the leading edge, is the critical factor to realize the high cooling performance of the design. Hence, the turning angle and turning internal radius of the cooling channel are two key parameters, and this paper focuses on the effects of these two parameters on the flow and heat transfer characteristics of the channel impingement cooling structure. Nine simplified single-channel models with different turning angles (45°, 60°, and 75°) and radiuses (0.6 mm, 0.9 mm, and 1.2 mm) were adopted to conduct the study, and the jet Reynolds number ranges from 10,000 to 40,000. The results show that the turning angle and turning internal radius affect the jet form significantly for the same mechanism. Small turning angle means large impingement, which leads to stream-wise counter-rotational vortices and high turbulence intensity, but increasing turning internal radius transfers the jet form from impingement jet to laminar layer attaching the target surface with low heat transfer. The turning internal radius has stronger effect than turning angle. With higher jet Reynolds number, both the heat transfer and total pressure loss increase dramatically, and the effects of geometrical parameters are clearer.

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