scholarly journals Effects of High Buoyancy Parameter on Flow and Heat Transfer of Two-Pass Smooth/Ribbed Channels

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 148
Author(s):  
Wenbin He ◽  
Ke Zhang ◽  
Junmei Wu ◽  
Jiang Lei ◽  
Pengfei Su ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Leading Edge ◽  
Maximum Growth ◽  
Operating Conditions ◽  
Internal Cooling ◽  
First Passage ◽  
Flow And Heat Transfer ◽  
Buoyancy Parameter ◽  
Smooth Channel

In order to deepen the understanding of rotating effects on internal cooling, the flow and heat transfer characteristics of 2-pass rotating rectangular smooth/ribbed channels are investigated by Reynolds-Averaged Navier-Stokes (RANS) simulation. Three rotating numbers (Ro = 0.10, 0.25, and 0.40) are simulated, and the maximum buoyancy parameter (Bo) reaches 5.0. The results show that the rotating buoyancy has significant effects on the flow and heat transfer under high Bo conditions. When Bo > 1.0, rotating buoyancy inducts flow separation near the leading edge (LE) in the first passage, while the air flow in the second passage shows a double-peak profile. With increased Bo, the heat transfer in the first passage is greatly increased, and the maximum growth rate occurs at Bo = 0.6~1.0. However, the heat transfer in the second passage has no obvious changes due to a strong turn effect. In the ribbed channel, rotating effects are much weaker than those in the smooth channel. This research helps to improve the understanding of the internal cooling heat transfer mechanism in land-based gas turbines under typical operating conditions.

Large Eddy Simulation of Flow and Heat Transfer in the Developing Flow Region of a Rotating Gas Turbine Blade Internal Cooling Duct With Coriolis and Buoyancy Forces

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
Evan A. Sewall ◽  
Danesh K. Tafti
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Flow Region ◽  
Internal Cooling ◽  
Heat Transfer Augmentation ◽  
Flow And Heat Transfer ◽  
Buoyancy Parameter ◽  
Developing Flow ◽  
Large Eddy

The problem of accurately predicting the flow and heat transfer in the ribbed internal cooling duct of a rotating gas turbine blade is addressed with the use of large eddy simulations (LES). Four calculations of the developing flow region of a rotating duct with ribs on opposite walls are used to study changes in the buoyancy parameter at a constant rotation rate. The Reynolds number is 20,000, the rotation number is 0.3, and the buoyancy parameter is varied between 0.00, 0.25, 0.45, and 0.65. Previous experimental studies have noted that leading wall heat transfer augmentation decreases as the buoyancy parameter increases with low buoyancy, but heat transfer then increases with high buoyancy. However, no consistent physical explanation has been given in the literature. The LES results from this study show that the initial decrease in augmentation with buoyancy is a result of larger separated regions at the leading wall. However, as the separated region spans the full pitch between ribs with an increase in buoyancy parameter, it leads to increased turbulence and increased entrainment of mainstream fluid, which is redirected toward the leading wall by the presence of a rib. The impinging mainstream fluid results in heat transfer augmentation in the region immediately upstream of a rib. The results obtained from this study are in very good agreement with previous experimental results.

Experimental and Numerical Conjugate Flow and Heat Transfer Investigation of a Shower-Head Cooled Turbine Guide Vane

1997 ◽  
Author(s):  
Dieter E. Bohn ◽  
Volker J. Becker ◽  
Agnes U. Rungen
Keyword(s):  
Heat Transfer ◽  
Thermal Analysis ◽  
Guide Vane ◽  
Leading Edge ◽  
Operating Conditions ◽  
Main Stream ◽  
Temperature Ratio ◽  
Stagnation Line ◽  
Flow And Heat Transfer ◽  
Turbine Guide Vane

This paper presents investigations of the development for a shower-head cooling configuration for a modern industrial turbine guide vane. One aim is to find suitable locations for cooling gas ejection with the lowest cooling gas mass flow possible. The investigations begin with a numerical experiment. After the prediction of a suitable configuration and operating parameters, the aerodynamics are investigated experimentally using a non-intrusive LDA technique. Once the aerodynamics had been validated, the numerical experiments were expanded to a thermal analysis of the vane. Our conjugate flow and heat transfer simulation enables thermal analysis of the vane body without us having to derive any heat transfer data beforehand. The calculations were performed for a temperature ratio of 0.5 between cooling gas and main stream. This temperature ratio is similar to the operating conditions found in current designs. The stagnation line moves under the influence of cooling gas ejection, which significantly influences the cooling gas distribution on the vane surface. The temperature distribution inside the vane is compared to a non-cooled test case. The simulation shows that the temperature peaks at the leading edge are reduced by between 18% and 44%.

Heat Transfer in a Two-Pass Rectangular Channel (AR=1:4) Under High Rotation Numbers

2008 ◽  
Vol 130 (8) ◽  
Author(s):  
Yao-Hsien Liu ◽  
Michael Huh ◽  
Je-Chin Han ◽  
Sanjay Chopra
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Rectangular Channel ◽  
Density Ratio ◽  
Leading Edge ◽  
First Passage ◽  
Test Channel ◽  
Sharp Bend ◽  
Buoyancy Parameter ◽  
Sharp Turn

This paper experimentally investigated the rotational effects on heat transfer in a two-pass rectangular channel (AR=1:4), which is applicable to the channel near the leading edge of the gas turbine blade. The test channel has radially outward flow in the first passage through a redirected sharp-bend entrance and radially inward flow in the second passage after a 180deg sharp turn. In the first passage, rotation effects on heat transfer are reduced by the redirected sharp-bend entrance. In the second passage, under rotating conditions, both leading and trailing surfaces experienced heat transfer enhancements above the stationary case. Rotation greatly increased heat transfer enhancement in the tip region up to a maximum Nu ratio (Nu∕Nus) of 2.4. The objective of the current study is to perform an extended parametric study of the low rotation number (0–0.3) and low buoyancy parameter (0–0.2) achieved previously. By varying the Reynolds numbers (10,000–40,000), the rotational speeds (0–400rpm), and the density ratios (inlet density ratio=0.10–0.16), the increased range of the rotation number and buoyancy parameter reached in this study are 0–0.67 and 0–2.0, respectively. The higher rotation number and buoyancy parameter have been correlated very well to predict the rotational heat transfer in the two-pass, 1:4 aspect ratio flow channel.

High Rotation Number Effect on Heat Transfer in a Triangular Channel With 45°, Inverted 45°, and 90° Ribs

2009 ◽  
Author(s):  
Yao-Hsien Liu ◽  
Michael Huh ◽  
Je-Chin Han ◽  
Hee-Koo Moon
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Rotation Number ◽  
Leading Edge ◽  
Stationary Condition ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Triangular Channel ◽  
Buoyancy Parameter ◽  
Cooling Passage

Heat transfer and pressure drop have been experimentally investigated in an equilateral triangular channel (Dh = 1.83cm), which can be used to simulate the internal cooling passage near the leading edge of a gas turbine blade. Three different rib configurations (45°, inverted 45°, and 90°) were tested at four different Reynolds numbers (10000–40000), each with five different rotational speeds (0–400 rpm). The rib pitch-to-height (P/e) ratio is 8 and the height-to-hydraulic diameter (e/Dh) ratio is 0.087 for every rib configuration. The rotation number and buoyancy parameter achieved in this study were 0–0.58 and 0–2.3, respectively. Both the rotation number and buoyancy parameter have been correlated to predict the rotational heat transfer in the ribbed equilateral triangular channel. For the stationary condition, staggered 45° angled ribs show the highest heat transfer enhancement. However, staggered 45° angled ribs and 90° ribs have the higher comparable heat transfer enhancement at rotating condition near the blade leading edge region.

Turning Guide Vane Effect on Internal Cooling of Two-Passage Channel With Parallel Ribs

2020 ◽  
Vol 142 (9) ◽  
Author(s):  
Mandana S. Saravani ◽  
Ryoichi S. Amano ◽  
Nicholas J. DiPasquale ◽  
Joseph Wayne Halmo
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Constant Heat Flux ◽  
Operating Conditions ◽  
Internal Cooling ◽  
Flux Boundary Condition ◽  
Flow And Heat Transfer ◽  
Computational Fluid Dynamics Simulations ◽  
Heat Flux Boundary Condition ◽  
Dynamics Simulations

Abstract The present work investigates the effects of various guide vane designs on the heat transfer enhancement of rotating U-duct configuration with parallel 45-deg ribs. The ribs were installed on the bottom wall of the channel, which has a constant heat flux boundary condition. The channel has a square cross section with a 5.08 cm hydraulic diameter. The first and second passes are 514 mm and 460 mm, respectively. The range of Reynolds number for turbulent flow is up to 35,000. The channel rotates at various speeds up to 600 rpm, which brings the maximum rotation number of 0.75. Several computational fluid dynamics simulations are carried out for this study to understand the effect of guide vanes on flow and heat transfer in serpentine channels under various operating conditions.

Investigation on the Internal Cooling of Two-Passage Channels With Parallel Ribs and Guide Vanes

2019 ◽  
Author(s):  
Ryoichi S. Amano ◽  
Mandana S. Saravani ◽  
Nicholas DiPasquale
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Constant Heat Flux ◽  
Operating Conditions ◽  
Internal Cooling ◽  
Flux Boundary Condition ◽  
Guide Vanes ◽  
Flow And Heat Transfer ◽  
Speed Up ◽  
Dynamics Simulations

Abstract The present work investigates the effects of various guide vane designs on the heat transfer enhancement of rotating U-Duct configuration with parallel 45-deg ribs. The ribs were installed on the bottom wall of the channel which has a constant heat flux boundary condition. The channel has a square cross-section with a 5.08 cm (2 in) hydraulic diameter. The first and second passes are 514 mm and 460 mm, respectively. The range of Reynolds number for turbulent flow is up to 35,000. The channel rotates in various speed up to 600 rpm which brings the maximum rotation number of 0.75. Several computational fluid dynamics simulations are carried out for this study to understand the effect of guide vanes on flow and heat transfer in serpentine channels under various operating conditions.

Heat Transfer in a Two-Pass Rectangular Channel (AR=1:4) Under High Rotation Numbers

2007 ◽  
Author(s):  
Yao-Hsien Liu ◽  
Michael Huh ◽  
Je-Chin Han ◽  
Sanjay Chopra
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Rectangular Channel ◽  
Leading Edge ◽  
Parameter Study ◽  
First Passage ◽  
Test Channel ◽  
Sharp Bend ◽  
Buoyancy Parameter ◽  
Sharp Turn

This paper experimentally investigated the rotational effects on heat transfer in a two-pass rectangular channel (AR=1:4), which is applicable to the channel near the leading edge of the gas turbine blade. The test channel has radially outward flow in the first passage through a re-directed sharp bend entrance and radially inward flow in the second passage after a 180° sharp turn. In the first passage, rotation effects on heat transfer are reduced by the re-directed sharp bend entrance. In the second passage, under rotating conditions, both leading and trailing surfaces experienced heat transfer enhancements above the stationary case. Rotation greatly increased heat transfer enhancement in the tip region up to a maximum Nu ratio (Nu/Nus) of 2.4. The objective of the current study is to perform an extended parameter study of the low rotation number (0–0.3) and low buoyancy parameter (0–0.2) achieved previously. By varying the Reynolds numbers (10000–40000) and the rotational speeds (0–400 rpm), the increased range of the rotation number and buoyancy parameter reached in this study are 0–0.67 and 0–1.9, respectively. The higher rotation number and buoyancy parameter have been correlated very well to predict the rotational heat transfer in the two-pass, 1:4 aspect ratio flow channel.

ICAS-GT: A European Collaborative Research Programme on Internal Cooling Air Systems for Gas Turbines

2002 ◽  
Author(s):  
Peter D. Smout ◽  
John W. Chew ◽  
Peter R. N. Childs
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Research Programme ◽  
Cavity Flow ◽  
Internal Cooling ◽  
Manufacturing Companies ◽  
Flow And Heat Transfer ◽  
Rotating Cavity ◽  
Internal Fluid Flow ◽  
Cooling Air

The Internal Cooling Air Systems for Gas Turbines (ICAS-GT) research programme, sponsored by the European Commission, ran from January 1998 to December 2000, and was undertaken by a consortium of ten gas turbine manufacturing companies and four universities. Research was concentrated in five discrete but related areas of the air system including turbine rim seals, rotating cavity flow and heat transfer, and turbine pre-swirl system effectiveness. In each case, experiments were conducted to extend the database of pressure, temperature, flow and heat transfer measurements to engine representative non-dimensional conditions. The data was used to develop correlations, and to validate CFD and FE calculation methods, for internal fluid flow and heat transfer. This paper summarises the outcome of the project by presenting a sample of experimental results from each technical work package. Examples of the associated CFD calculations are included to illustrate the progress made in developing validated tools for predicting rotating cavity flow and heat transfer over an engine representative range of flow conditions.

Effect of Entrance Geometry on Heat Transfer in a Narrow (AR=1:4) Rectangular Two Pass Channel With Smooth and Ribbed Walls

2011 ◽  
Author(s):  
Krishnendu Saha ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Test Section ◽  
Leading Edge ◽  
Internal Cooling ◽  
Enhance Heat Transfer ◽  
Developing Regions ◽  
Smooth Channel ◽  
Mainstream Flow ◽  
First Pass ◽  
Channel Configuration

This paper studies the effect of entrance geometries on the heat transfer in a narrow aspect ratio (AR=1:4) rectangular internal cooling channel, representative of a leading edge of a gas turbine blade. Detailed heat transfer coefficient distributions are measured for three different entrance geometries: S-shape entrance, 90 degree bend entrance and a twisted entrance with changing AR. Both smooth and ribbed channels are used in a two pass channel configuration. A baseline straight-entry channel is used as a reference for comparison. The tests are done for Reynolds number ranging from 15000 to 55000. The ribs are placed at an angle of 45° to the mainstream flow. The results show that the effects of entrance geometry persist throughout the first pass (up to a distance of 9 times the hydraulic diameter) for the smooth channel. All the entrance geometries provided enhancement in heat transfer compared to the straight fully developed entrance, with the 90 degree bend entrance providing the highest enhancement. The effect of entrance is less pronounced for the ribbed test section case with the effects confined more in the early developing regions. The 90 degree bend entrance and the twisted-entry cases enhance heat transfer for the ribbed test section, while the S-shape entrance reduces the heat transfer for the ribbed test section relative to the straight entry channel.

Large Eddy Simulation of Flow and Heat Transfer in the Developing Flow Region of a Rotating Gas Turbine Blade Internal Cooling Duct With Coriolis and Buoyancy Forces

2005 ◽  
Author(s):  
Evan A. Sewall ◽  
Danesh K. Tafti
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Flow Region ◽  
Internal Cooling ◽  
Heat Transfer Augmentation ◽  
Flow And Heat Transfer ◽  
Buoyancy Parameter ◽  
Developing Flow ◽  
Large Eddy

The problem of accurately predicting the flow and heat transfer in the ribbed internal cooling duct of a rotating gas turbine blade is addressed with the use of large eddy simulations (LES). Four calculations of the developing flow region of a rotating duct with ribs on opposite walls are used to study changes in the buoyancy parameter at a constant rotation rate. The Reynolds number is 20,000, the rotation number is 0.3, and the buoyancy parameter is varied between 0.00, 0.25, 0.45, and 0.65. Previous experimental studies have noted that leading wall heat transfer augmentation decreases as the buoyancy parameter increases with low buoyancy, but heat transfer then increases with high buoyancy. However, no consistent physical explanation has been given in the literature. The LES results from this study show that the initial decrease in augmentation with buoyancy is a result of larger separated regions at the leading wall. However, as the separated region spans the full pitch between ribs with an increase in buoyancy parameter, it leads to increased turbulence and increased entrainment of mainstream fluid which is redirected toward the leading wall by the presence of a rib. The impinging mainstream fluid results in heat transfer augmentation in the region immediately upstream of a rib. The results obtained from this study are in very good agreement with previous experimental results.

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