scholarly journals Validation of a CFD Approach for Gas Turbine Internal Cooling Passage Heat Transfer Prediction

2015 ◽  
Author(s):  
Daniel G Wilde
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Internal Cooling ◽  
Cooling Passage ◽  
Internal Cooling Passage

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.

Computation of Flow and Heat Transfer of a Blade Internal Cooling Passage With Truncated V-Shaped Ribs on Opposite Walls

2012 ◽  
Author(s):  
Shian Li ◽  
Gongnan Xie ◽  
Weihong Zhang ◽  
Bengt Sundén
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Turbine Engine ◽  
Flow And Heat Transfer ◽  
Cooling Passage ◽  
Internal Cooling Passage

The inlet temperature of gas turbine engine is continuously increased to achieve higher thermal efficiency and power output. To prevent from the temperature exceeding the melting point of the blade material, ribs are commonly used in the mid-section of internal blade to augment the heat transfer from blade wall to the coolant. In this study, turbulent flow and heat transfer of a rectangular cooling passage with continuous or truncated 45-deg V-shaped ribs on opposite walls have been investigated numerically. The inlet Reynolds numbers are ranging from 12,000 to 60,000 and the low-Re k-ε model is selected for the turbulent computations. The complex three-dimensional fluid flow in the internal coolant passages and the corresponding heat transfer over the side-walls and rib-walls are presented and the thermal performances of the ribbed passages are compared as well. It is shown that the passage with truncated V-shaped ribs on opposite walls is very effective in improving the heat transfer performance with a low pressure loss, and thus could be suggested to be applied to gas turbine blade internal cooling.

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.

Effect of Rib Density on Flow and Heat Transfer in an Internal Cooling Passage

2016 ◽  
Author(s):  
Tomoko Hagari ◽  
Katsuhiko Ishida ◽  
Kenichiro Takeishi ◽  
Masaharu Komiyama ◽  
Yutaka Oda
Keyword(s):  
Heat Transfer ◽  
Low Frequency ◽  
Temperature Fields ◽  
Internal Cooling ◽  
Flow And Heat Transfer ◽  
Large Vortex ◽  
Internally Cooled ◽  
Rib Turbulators ◽  
Cooling Passage ◽  
Internal Cooling Passage

Effect of rib density on mechanism of flow and heat transfer enhancement in an internally-cooled channel with rib turbulators have been investigated numerically. Based on the experimental setup in the previous study [32], flowfield and heat transfer coefficient distributions were predicted with LES approach. The rib pitch-to-height ratios were 3 and 11, and Reynolds number based on the channel hydraulic diameter and bulk velocity was set at 30,000. Comparison of time-averaged flow and heat transfer characteristics between numerical and experimental results showed that prediction accuracy of the present numerical setup was reasonable. The previous study [33] suggested that, for higher rib density, low-frequency velocity fluctuation characterizes heat transfer. To investigate its flow and heat transfer mechanism, instantaneous velocity and temperature fields were compared. For smaller rib density, small vortices constantly occurred from each rib and were dissipated into the mainstream before reaching the next rib. On the other hand, for higher rib density, relatively large vortex occurs above the ribs in addition to smaller vortices inside the cavity between the ribs. The large vortex occurs intermittently behind the second rib of the channel, and increases its size by interacting with smaller vortex downstream. For each rib pitch, similar trend was observed in the measured result obtained using Particle Image Velocimetry. This unsteady vortex structure would contribute to enhancing the heat transfer of a cooling channel with densely-arranged rib turbulators.

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.

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.

Applications of Advanced Liquid Crystal Video Thermography to Turbine Cooling Passage Heat Transfer Measurement

1996 ◽  
Author(s):  
Robert P. Campbell ◽  
Michael J. Molezzi
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Gas Turbine ◽  
Leading Edge ◽  
Internal Cooling ◽  
Thermochromic Liquid Crystal ◽  
Transfer Coefficients ◽  
Full Field ◽  
Multiple Data Sets ◽  
Cooling Passage

Over the past few years advances in thermochromic liquid crystal (TLC) thermography have improved its usefulness as a quantitative temperature measurement technique. Many of these improvements have been discussed in the literature but few have been directly applied to solving gas turbine heat transfer problems. The purpose of this work is to combine the best of these techniques into an advanced, easy to use, low cost system which can provide accurate, rapid and complete heat transfer data for advanced gas turbine development. The older, more common technique of using narrow band liquid crystals to map isotherm distributions has been updated to use wide temperature range crystals with full hue-temperature calibrations over their entire response range with accuracy as good or better than thermocouples. The system consists of an RGB video camera, a hue, saturation and intensity (HS1) framegrabber, on-axis lighting and a linear thermal gradient TLC calibrator. Algorithms have been developed for automated data validation, spatial transformations of data taken on non-planar surfaces and superposition of multiple data sets to construct full field data over surfaces with wide ranges of heat transfer coefficients (h). Instead of yielding mean h, h at a few thermocouple locations or h at individual isotherms, this system provides continuous distributions of h. These techniques have been used to map the heat transfer coefficient distributions in advanced power generation gas turbine internal cooling passages. These include serpentine passages with and without turbulators, leading edge passages and 180° rums. Results are presented in full field plots of heat transfer enhancement, Nu(x,y)/Nudb.

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