Experimental and Numerical Investigation of the Flow in a Trailing Edge Ribbed Internal Cooling Passage

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Seungchan Baek ◽  
Sangjoon Lee ◽  
Wontae Hwang ◽  
Jung Shin Park
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Sharp Edge ◽  
Internal Cooling ◽  
Mean Flow ◽  
Trailing Edge ◽  
Triangular Channel ◽  
The Mean ◽  
Cooling Passage ◽  
Internal Cooling Passage

The flow field in a ribbed triangular channel representing the trailing edge internal cooling passage of a gas turbine high-pressure turbine blade is investigated via magnetic resonance velocimetry (MRV) and large eddy simulation (LES). The results are compared to a baseline channel with no ribs. LES predictions of the mean velocity fields are validated by the MRV results. In the case of the baseline triangular channel with no ribs, the mean flow and turbulence level at the sharp corner are small, which would correspond to poor heat transfer in an actual trailing edge. For the staggered ribbed channel, turbulent mixing is enhanced, and flow velocity and turbulence intensity at the sharp edge increase. This is due to secondary flow induced by the ribs moving toward the sharp edge in the center of the channel. This effect is expected to enhance internal convective heat transfer for the turbine blade trailing edge.

Experimental and Numerical Investigation of the Flow in a Trailing Edge Ribbed Internal Cooling Passage

2018 ◽  
Author(s):  
Seungchan Baek ◽  
Sangjoon Lee ◽  
Wontae Hwang ◽  
Jung Shin Park
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Sharp Edge ◽  
Internal Cooling ◽  
Mean Flow ◽  
Trailing Edge ◽  
Triangular Channel ◽  
The Mean ◽  
Cooling Passage ◽  
Internal Cooling Passage

The flow field in a ribbed triangular channel representing the trailing edge internal cooling passage of a gas turbine high pressure turbine blade is investigated via Magnetic Resonance Velocimetry (MRV) and Large Eddy Simulation (LES). Results are compared to a baseline channel with no ribs. LES predictions of the mean velocity fields are validated by the MRV results. In the case of the baseline triangular channel with no ribs, the mean flow and turbulence level at the sharp corner are small, which would correspond to poor heat transfer in an actual trailing edge. For the staggered ribbed channel, turbulent mixing is enhanced, and flow velocity and turbulence intensity at the sharp edge increase. This is due to secondary flow induced by the ribs moving toward the sharp edge in the center of the channel. This effect is expected to enhance internal convective heat transfer for the turbine blade trailing edge.

Computational Analysis of Side-Wall Heat Transfer of a Turbine Blade Internal Cooling Passage With Truncated Ribs on Opposite Walls

2012 ◽  
Author(s):  
Shian Li ◽  
Gongnan Xie ◽  
Bengt Sundén ◽  
Weihong Zhang
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Thermal Stresses ◽  
Side Wall ◽  
Leading Edge ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Wall Heat Transfer ◽  
Cooling Passage ◽  
Internal Cooling Passage

A problem involved in the increase of the turbine inlet temperature of gas turbine engine is the failure of material because of excessive thermal stresses. This requires cooling methods to withstand the increase of the inlet temperature. Rib turbulators are often used in the mid-section of internal cooling ducts to augment the heat transfer from blade wall to the coolant. This study numerically investigates side-wall heat transfer of a rectangular passage with the leading/trailing walls being roughened by staggered ribs whose length is less than the passage width. Such a passage corresponds to the internal cooling passage near the leading edge of a turbine blade. The inlet Reynolds number is ranging from 12,000 to 60,000. The detailed 3D fluid flow and heat transfer over the side-wall are presented. The overall performances of several ribbed passages are evaluated and compared. It is found that the side-wall heat transfer coefficients of the passage with truncated (continuous) ribs on opposite walls are about 20%–27% (28%–43%) higher than those of a passage without ribs, while the pressure loss could be reduced compared to a passage with continuous ribs. It is suggested that the usage of truncated ribs is a suitable way to augment the side-wall heat transfer and improve the flow structure near the leading edge.

Numerical Investigation on the Modified Bend Geometry of a Rotating Multipass Internal Cooling Passage in a Gas Turbine Blade

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Naris Pattanaprates ◽  
Ekachai Juntasaro ◽  
Varangrat Juntasaro
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Internal Cooling ◽  
Gas Turbine Blade ◽  
Reduced Pressure ◽  
Improve Heat Transfer ◽  
Cooling Passage ◽  
Internal Cooling Passage

Abstract The present work is aimed to investigate whether the modification to the bend geometry of a multipass internal cooling passage in a gas turbine blade can enhance heat transfer and reduce pressure drop. The two-pass channel and the four-pass channel are modified at the bend from the U shape to the bulb and bow shape. The first objective of the work is to investigate whether the modified design will still improve heat transfer with reduced pressure drop in a four-pass channel as in the case of a two-pass channel. It is found out that, unlike the two-pass channel, the heat transfer is not improved but the pressure drop is still reduced for the four-pass channel. The second objective is to investigate the rotating effect on heat transfer and pressure drop in the cases of two-pass and four-pass channels for both original and modified designs. It is found out that heat transfer is improved with reduced pressure drop for all cases. However, the modified design results in the less improvement on heat transfer and lower reduced pressure drop as the rotation number increases. It can be concluded from the present work that the modification can solve the problem of pressure drop without causing the degradation of heat transfer for all cases. The two-pass channel with modified bend results in the highest heat transfer and the lowest pressure drop for rotating cases.

Large Eddy Simulation of the Developing Region of a Stationary Ribbed Internal Turbine Blade Cooling Channel

2004 ◽  
Author(s):  
Evan A. Sewall ◽  
Danesh K. Tafti
Keyword(s):  
Heat Transfer ◽  
Large Eddy Simulation ◽  
Turbine Blade ◽  
Internal Cooling ◽  
Mean Flow ◽  
Heat Transfer Augmentation ◽  
The Third ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Cooling Passage

This study reports on a Large Eddy Simulation (LES) of the entrance section of a gas turbine blade internal cooling passage. The channel is fitted with in-line turbulators orthogonal to the flow, and the domain studied covers the first six ribs of the channel. The rib height-to-hydraulic diameter ratio (e/Dh) is 0.1, and the rib pitch-to-rib height ratio (P/e) is 10. A constant temperature boundary condition is imposed on the walls and the ribs, and the flow Reynolds number is 20,000. Results indicate that the mean flow is essentially fully developed by the fifth rib. Turbulent kinetic energy near the ribbed wall approaches fully developed values very quickly by the third or fourth ribs. However, turbulent intensities at the center of the duct are not fully developed by the sixth rib. As a consequence, heat transfer augmentation on the ribbed walls reaches a fully developed state quickly after the third rib, whereas, the smooth wall heat transfer augmentation shows a slight but steady increasing trend toward the fully developed value up to the sixth rib. Both augmentation ratios are to within 10% of their fully developed values after the third rib.

scholarly journals A Computational Visualization of Three Dimensional Flow: Finding Optimum Heat Transfer and Pressure Drop Characteristics From Short Cross-Pin Arrays and Comparison With Two Dimensional Calculations

1999 ◽  
Author(s):  
E. E. Donahoo ◽  
C. Camci ◽  
A. K. Kulkarni ◽  
A. D. Belegundu
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Structural Integrity ◽  
Turbine Blades ◽  
Circular Cross Section ◽  
Internal Cooling ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
Spacing Ratio ◽  
Cooling Passage

There are many heat transfer augmentation methods that are employed in turbine blade design, such as impingement cooling, film cooling, serpentine passages, trip strips, vortex chambers, and pin fins. The use of crosspins in the trailing edge section of turbine blades is commonly a viable option due to their ability to promote turbulence as well as supply structural integrity and stiffness to the blade itself. Numerous crosspin shapes and arrangements are possible, but only certain configurations offer high heat transfer capability while maintaining taw total pressure loss. This study preseots results from 3-D numerical simulations of airflow through a turbine blade internal cooling passage. The simulations model viscous flow and heat transfer over full crosspins of circular cross-section with fixed height-to-diameter ratio of 0.5, fixed transverse-to-diameter spacing ratio of 1.5, and varying streamwise spacing. Preliminary analysis indicates that endwall effects dominate the flow and heat transfer at lower Reynolds numbers. The flow dynamics involved with the relative dose proximity of the endwalls for such short crosspins have a definite influeoce on crosspin efficiency for downstream rows.

Unsteady Effects on Trailing Edge Cooling

2005 ◽  
Vol 127 (4) ◽  
pp. 388-392 ◽  
Author(s):  
G. Medic ◽  
P. A. Durbin
Keyword(s):  
Turbine Blade ◽  
Pressure Side ◽  
Streamwise Vortices ◽  
Mean Flow ◽  
Trailing Edge ◽  
Cooling Flows ◽  
The Mean ◽  
Adiabatic Effectiveness ◽  
Surface Jet ◽  
Unsteady Effects

It is shown how natural and forced unsteadiness play a major role in turbine blade trailing edge cooling flows. Reynolds averaged simulations are presented for a surface jet in coflow, resembling the geometry of the pressure side breakout on a turbine blade. Steady computations show very effective cooling; however, when natural—or even moreso, forced—unsteadiness is allowed, the adiabatic effectiveness decreases substantially. Streamwise vortices in the mean flow are found to be the cause of the increased heat transfer.

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.

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