Effects of Guide Vanes on the Tip Heat Transfer Enhancement of a Turbine Blade

2011 ◽  
Author(s):  
Gongnan Xie ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Turbine Blade ◽  
Pressure Loss ◽  
Transfer Enhancement ◽  
Guide Vanes ◽  
Flow And Heat Transfer ◽  
Numerical Predictions ◽  
Blade Tip

Gas turbine blade tips encounter large heat load as they are exposed to the high temperature gas. A common way to cool the blade and its tip is to design serpentine passages with 180-deg turns under the blade tip-cap inside the turbine blade. Improved internal convective cooling is therefore required to increase the blade tip life time. This paper presents numerical predictions of turbulent fluid flow and heat transfer through two-pass channels with and without guide vanes placed in the turn regions using RANS turbulence modeling. The effects of adding guide vanes on the tip-wall heat transfer enhancement and the channel pressure loss were analyzed. The guide vanes have a height identical to that of the channel. The inlet Reynolds numbers are ranging from 100,000 to 600,000. The detailed three-dimensional fluid flow and heat transfer over the tip-walls are presented. The overall performances of several two-pass channels are also evaluated and compared. It is found that the tip heat transfer coefficients of the channels with guide vanes are 10∼60% higher than that of a channel without guide vanes, while the pressure loss might be reduced when the guide vanes are properly designed and located, otherwise the pressure loss is expected to be increased severely. It is suggested that the usage of proper guide vanes is a suitable way to augment the blade tip heat transfer and improve the flow structure, but is not the most effective way compared to the augmentation by surface modifications imposed on the tip-wall directly.

Flow and Heat Transfer Characteristics in Models of Turbine Blade Tip-Walls With Three Kinds of Turning Vanes

2018 ◽  
Author(s):  
Bin Wu ◽  
Xing Yang ◽  
Lv Ye ◽  
Zhao Liu ◽  
Yu Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Double Layer ◽  
Pressure Loss ◽  
Stokes Equations ◽  
Wall Heat Transfer ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Blade Tip

In this paper, effects of three kinds of turning vanes on flow and heat transfer of turbine blade tip-walls with a U-shaped channel have been numerically studied. Numerical simulations are performed to solve three-dimensional, steady, Reynolds-averaged Navier-Stokes equations with the standard k-ω turbulence model. The aspect ratio (AR) and the hydraulic diameter of the channel are 2 and 93.13 mm, respectively. The effects of single-layer, double-layer and double-layer dome-shaped turning vanes in the turn region on the tip-wall heat transfer and overall pressure loss of rectangular U-shaped channels are analyzed. Detailed flow and heat transfer characteristics over the tip-walls, as well as the overall performance, are presented and compared with each other. Results show that the tip-wall heat transfer coefficients with double-layer dome-shaped turning vanes are the highest among the three cases. Double-layer dome-shaped turning vanes can promote the lateral spreading of secondary flow and effectively increase the uniformity of heat transfer on the tip-wall. More importantly, this structure can make the cooling air expand and accelerate at the center region of the top of the U-shaped channel, resulting in more heat to be removed from the tip-wall. Additionally, double-layer dome-shaped turning vanes can effectively reduce the pressure loss of the channel.

Numerical investigation of fluid flow structure and heat transfer in a passage with continuous and truncated V-shaped ribs

2015 ◽  
Vol 25 (1) ◽  
pp. 171-189 ◽  
Author(s):  
Shian Li ◽  
Gongnan Xie ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Content Type ◽  
Flow And Heat Transfer

Purpose – The employment of continuous ribs in a passage involves a noticeable pressure drop penalty, while other studies have shown that truncated ribs may provide a potential to reduce the pressure drop while keeping a significant heat transfer enhancement. The purpose of this paper is to perform computer-aided simulations of turbulent flow and heat transfer of a rectangular cooling passage with continuous or truncated 45-deg V-shaped ribs on opposite walls. Design/methodology/approach – Computational fluid dynamics technique is used to study the fluid flow and heat transfer characteristics in a three-dimensional rectangular passage with continuous and truncated V-shaped ribs. Findings – The inlet Reynolds number, based on the hydraulic diameter, is ranged from 12,000 to 60,000 and a low-Re k-e model is selected for the turbulent computations. The local flow structure and heat transfer in the internal cooling passages are presented and the thermal performances of the ribbed passages are compared. It is found that the passage with truncated V-shaped ribs on opposite walls provides nearly equivalent heat transfer enhancement with a lower (about 17 percent at high Reynolds number of 60,000) pressure loss compared to a passage with continuous V-shaped ribs or continuous transversal ribs. Research limitations/implications – The fluid is incompressible with constant thermophysical properties and the flow is steady. The passage is stationary. Practical implications – New and additional data will be helpful in the design of ribbed passages to achieve a good thermal performance. Originality/value – The results imply that truncated V-shaped ribs are very effective in improving the thermal performance and thus are suggested to be applied in gas turbine blade internal cooling, especially at high velocity or Reynolds number.

Numerical Study on the Flow and Heat Transfer Characteristics in Rectangular Channels With Grooves and Different Protrusions

2017 ◽  
Author(s):  
Feng Zhang ◽  
Xinjun Wang ◽  
Jun Li ◽  
Daren Zheng ◽  
Junfei Zhou
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Thermal Performance ◽  
Pressure Loss ◽  
Numerical Study ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Rectangular Channels

The present work represents a numerical study on the flow and heat transfer characteristics in rectangular channels with protrusion-grooved turbulators. The Reynolds averaged Navier-Stokes equations, coupled with SST turbulence model, are adopted and solved. In this paper, six geometric protrusion shapes (circular, rectangular, triangular, trapezoidal, circular with leading round concave and circular with trailing round concave) are selected to perform the study. The flow structure, heat transfer enhancement, friction factor as well as thermal performance factor of the rectangular channel fitted with combined groove and different protrusions have been obtained at the Reynolds number ranging from 5000 to 20000. The results indicate that the protrusion shapes affect the velocity distribution near the groove surface. The case of circular protrusion with leading round concave provides the highest overall heat transfer enhancement, while it also causes the highest pressure loss penalty. The case of rectangular protrusion has the lowest overall heat transfer enhancement with high pressure loss penalty. The case of circular protrusion has similar overall heat transfer enhancement with cases of trapezoidal protrusion as well as circular protrusion with trailing round concave, but the pressure loss penalty of the case of circular protrusion is the lowest. In addition, the best overall thermal performance can be observed for circular protrusion-grooved channel.

Flow and Heat Transfer Enhancement of Nanofluids in Microchannel With Blocks and Grooves

2013 ◽  
Author(s):  
Ping Li ◽  
Jianhui Chen ◽  
Huancheng Qu ◽  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Energy Transport ◽  
Recirculation Zone ◽  
Volume Concentration ◽  
Flow Analysis ◽  
Transfer Enhancement ◽  
Flow And Heat Transfer

A code based on the lattice-Boltzmann method was programmed. At various Reynolds numbers, simulations of the Cu/water nanofluid flow structure and heat transfer performance in a two dimensional microchannel with blocks (Re = 10–100) and grooves (Re = 50–200) were conducted, and the factors affecting the flow and heat transfer were explored. The flow and heat transfer of nanofluids with nanoparticle volume concentration of 0.5%, 1.0%, 1.5% and 2.0% were simulated, obtaining the velocity and temperature distributions to compare with the results of base fluid. Flow analysis showed that recirculation zones formed behind the blocks and in the grooves when nanofluids flowed in the microchannel, and the size of recirculation zone increased with the increase of Reynolds number and nanoparticle volume concentration. The core of the recirculation zone in the groove gradually moved to the right wall as Reynolds number increased at the same nanoparticle volume concentration, and the direction of the main flow was getting horizontal. Heat transfer results indicated that the addition of nanoparticles could promote fluid flow and energy transport, so that the thermal boundary layer thickness decreased and the heat transfer was enhanced. The heat transfer enhancement increased with the increase of Reynolds number and nanoparticle volume concentration. It was also shown that the heat transfer enhancement by increasing the Reynolds number was limited. The results could give a fundamental understanding for designing highly efficient heat exchangers.

Heat Transfer Enhancement for a Turbine Blade Leading Edge Passage Using Various Turbulator Geometries

2014 ◽  
Author(s):  
H. Saxer-Felici ◽  
S. Naik ◽  
M. Gritsch ◽  
A. Sedlov
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Pressure Loss ◽  
Leading Edge ◽  
Heavy Duty ◽  
Transfer Enhancement ◽  
Pressure Suction ◽  
Blade Leading Edge

The leading edge regions of first stages blades and vanes of heavy-duty gas turbines are subjected to high thermal loads. Efficient cooling allows the reduction of the coolant mass flow required to drive the metal temperatures to a range satisfying mechanical integrity requirements. This paper investigates the heat transfer and pressure loss behavior for the internal cooling channel of a leading edge of a gas turbine blade. The geometrical profile of the blade leading edge and the operating conditions considered are representative of that normally found in a heavy-duty gas turbine. The geometries investigated cover angled turbulators of various angles, pitches and heights. Partial and full length rib coverage as well as broken ribs are also considered. In addition, the impact of including fillets in the geometry is assessed. The experimental and numerical studies are conducted at passage Reynolds numbers ranging from 7.5·104 to 1.3·105. Experiments are performed using Perspex models at atmospheric conditions. The internal heat transfer coefficients on all internal surfaces are measured via thermochromic liquid crystal method and the pressure drop is measured via pressure taps distributed along the channel. The predicted and experimental heat transfer enhancements are compared on the leading-edge, pressure, suction and web surfaces. The overall non dimensional cooling performance numbers are also compared for the various geometries. The results show a large variation of heat transfer enhancement and pressure loss over the various turbulator geometries investigated. Also, the complex flow structures lead to highly differentiated results for leading edge, pressure, suction and web surfaces. Although some configurations with higher ribs lead to increased heat transfer, the associated pressure losses are also shown to increase substantially.

The Effect of the Corrugation Rib Angle of Attack on the Fluid Flow and Heat Transfer Characteristics Inside Corrugated Ribbed Passage

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
A. M. I. Mohamed ◽  
R. Hoettiba ◽  
A. M. Saif
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Heat Transfer Enhancement ◽  
Angle Of Attack ◽  
Navier Stokes ◽  
Transfer Enhancement ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Flow Field Characteristics

Heat transfer enhancement using corrugated ribbed passages is one of the common enhancement techniques inside heat exchangers. The present study investigated numerically the effect of the corrugation rib angle of attack on the fluid flow and heat transfer characteristics inside the corrugated ribbed passage. The commercial computational fluid dynamics code PHOENICS 2006 was used to perform the numerical analysis by solving the Navier–Stokes and energy equations. The experimental part of this study was used only to validate the numerical model, and a good agreement between the experimental results and the model was obtained. The flow field characteristics and heat transfer enhancement were numerically investigated for different corrugated rib angles of attack as follows: 90 deg, 105 deg, 120 deg, 135 deg, and 150 deg. The corrugation rib angle of attack has a great effect on the reversed flow zone, the flow reattachments, and the enhancement of the heat transfer coefficient through the duct. The recommended rib angle of attack, which gives the optimum thermohydraulic performance, is found to be between 135 deg and 150 deg. The value of the maximum thermohydraulic performance is about 3.6 for the 150 deg rib angle of attack at a Reynolds number equal to 10,000.

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