Flow Visualization of Microscale Effusion and Transpiration Cooling on Semi-cylinder for Gas Turbine Cooling Application

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Dong Hwan Shin ◽  
Yeonghwan Kim ◽  
Jin Sub Kim ◽  
Do Won Kang ◽  
Jeong-Lak Sohn ◽  
...  
Keyword(s):  
Flow Visualization ◽  
Gas Turbine ◽  
Metal Surface ◽  
Flow Behavior ◽  
Porous Metal ◽  
Air Cooling ◽  
Transpiration Cooling ◽  
Turbine Cooling ◽  
High Efficient ◽  
Gas Turbine Cooling

Abstract Effusion and transpiration cooling can be an attractive method of air cooling for the next generation high-efficient gas turbine which has a very hot gas temperature over 1,600°C (TRIT). For higher effectiveness of air cooling for a gas turbine vane and blade, the air-cooled flow through effusion-holes and porous metal surface should not penetrate into the mainstream flow but still remain within the thermal boundary layer. The present visualization study examines flow behavior of microscale effusion and transpiration cooling on semi-cylinder. The secondary flow issued from the effusion-holes and porous metal surface is visualized by a smoke-tube method which consists of oil droplet generator, diode pumped solid state (DPSS) laser and highspeed imaging. The flow visualization of microscale effusion and transpiration cooling on semi-cylinder is characterized with various blowing ratios. It is found that the transpiration cooling consumes less coolant air than effusion cooling and has better cooling effectiveness based on the same flow rate of coolant air. Visual criteria can be provided to maintain the effusion and transpiration cooling on semi-cylinder for gas turbine cooling application. [This work was supported by the National Research Council of Science and Technology (NST) grant funded by the Ministry of Science and ICT, Korea (Grant No. KIMM-NK219B).]

scholarly journals Two-Stage Evaporative Inlet Air Gas Turbine Cooling

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1382
Author(s):  
Obida Zeitoun
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Evaporative Cooling ◽  
Air Cooling ◽  
Vapor Compression ◽  
Two Stage ◽  
Turbine Cooling ◽  
Riyadh City ◽  
Vapor Compression Refrigeration ◽  
Gas Turbine Cooling

Gas turbine inlet air-cooling (TIAC) is an established technology for augmenting gas turbine output and efficiency, especially in hot regions. TIAC using evaporative cooling is suitable for hot, dry regions; however, the cooling is limited by the ambient wet-bulb temperature. This study investigates two-stage evaporative TIAC under the harsh weather of Riyadh city. The two-stage evaporative TIAC system consists of indirect and direct evaporative stages. In the indirect stage, air is precooled using water cooled in a cooling tower. In the direct stage, adiabatic saturation cools the air. This investigation was conducted for the GE 7001EA gas turbine model. Thermoflex software was used to simulate the GE 7001EA gas turbine using different TIAC systems including evaporative, two-stage evaporative, hybrid absorption refrigeration evaporative and hybrid vapor-compression refrigeration evaporative cooling systems. Comparisons of different performance parameters of gas turbines were conducted. The added annual profit and payback period were estimated for different TIAC systems.

Two-Phase Transpiration Cooling

1982 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
Transpiration Cooling ◽  
System Behavior ◽  
Two Phase ◽  
Modes Of Operation ◽  
Considerable Potential ◽  
Closed Form Solutions ◽  
Turbine Cooling ◽  
Gas Turbine Cooling ◽  
Hot Surface

Two-phase transpiration is shown to possess considerable potential for gas turbine cooling. In this concept, water fed into a porous component boils within the wall. The resulting steam issues from the hot surface forming the transpiration film. A model for the performance of such a system is developed. Assuming constant properties and a linear reduction of Stanton number with transpiration rate, closed-form solutions are obtained. The governing dimensionless parameters are identified, the system behavior predicted, and the modes of operation delineated. Those are defined as two-phase, partially-flooded, and completely-flooded modes. At low values of a certain “modified Peclet number,” the two-phase mode is unstable and the system tends to flood. Large values of this parameter indicate stable, well-regulated behavior. Discussions on gas turbine applications are presented. A typical numerical example is given in the Appendix.

Two-Phase Transpiration Cooling

1983 ◽  
Vol 105 (1) ◽  
pp. 106-113
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
Transpiration Cooling ◽  
System Behavior ◽  
Two Phase ◽  
Modes Of Operation ◽  
Considerable Potential ◽  
Closed Form Solutions ◽  
Turbine Cooling ◽  
Gas Turbine Cooling ◽  
Hot Surface

Two-phase transpiration is shown to possess considerable potential for gas turbine cooling. In this concept, water fed into a porous component boils within the wall. The resulting steam issues from the hot surface forming the transpiration film. A model for the performance of such a system is developed. Assuming constant properties and a linear reduction of Stanton number with transpiration rate, closed-form solutions are obtained. The governing dimensionless parameters are identified, the system behavior predicted, and the modes of operation delineated. Those are defined as two-phase, partially-flooded, and completely-flooded modes. At low values of a certain “modified Peclet number,” the two-phase mode is unstable and the system tends to flood. Large values of this parameter indicate stable, well-regulated behavior. Discussions on gas turbine applications are presented. A typical numerical example is given in the Appendix.

Build Direction Effects on Additively Manufactured Channels

2015 ◽  
Author(s):  
Jacob C. Snyder ◽  
Curtis K. Stimpson ◽  
Karen A. Thole ◽  
Dominic Mongillo
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Pressure Loss ◽  
Small Scale ◽  
Turbine Cooling ◽  
Gas Turbine Cooling ◽  
Gas Turbine Heat Transfer ◽  
Manufacturing Techniques ◽  
Traditional Manufacturing

With the advances of Direct Metal Laser Sintering (DMLS), also generically referred to as additive manufacturing, novel geometric features of internal channels for gas turbine cooling can be achieved beyond those features using traditional manufacturing techniques. There are many variables, however, in the DMLS process that affect the final quality of the part. Of most interest to gas turbine heat transfer designers are the roughness levels and tolerance levels that can be held for the internal channels. This study investigates the effect of DMLS build direction and channel shape on the pressure loss and heat transfer measurements of small scale channels. Results indicate that differences in pressure loss occur between the test cases with differing channel shapes and build directions, while little change is measured in heat transfer performance.

Scaling Heat-Transfer Coefficients Measured Under Laboratory Conditions to Engine Conditions

2017 ◽  
Author(s):  
T. I.-P. Shih ◽  
C.-S. Lee ◽  
K. M. Bryden
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Scaling Factor ◽  
Rate Of Change ◽  
Transfer Enhancement ◽  
Scaling Factors ◽  
Turbine Cooling ◽  
Pin Fins ◽  
Gas Turbine Cooling

Almost all measurements of the heat-transfer coefficient (HTC) or Nusselt number (Nu) in gas-turbine cooling passages with heat-transfer enhancement features such as pin fins and ribs have been made under conditions, where the wall-to-bulk temperature, Tw/Tb, is near unity. Since Tw/Tb in gas-turbine cooling passages can be as high as 2.2 and vary appreciably along the passage, this study examines if it is necessary to match the rate of change in Tw/Tb when measuring Nu, whether Nu measured at Tw/Tb near unity needs to be scaled before used in design and analysis of turbine cooling, and could that scaling for ducts with heat-transfer enhancement features be obtained from scaling factors for smooth ducts because those scaling factors exist in the literature. In this study, a review of the data in the literature shows that it is unnecessary to match the rate of change in Tw/Tb for smooth ducts at least for the rates that occur in gas turbines. For ducts with heat-transfer enhancement features, it is still an open question. This study also shows Nu measured at Tw/Tb near unity needs to be scale to the correct Tw/Tb before it can be used for engine conditions. By using steady RANS analysis of the flow and heat transfer in a cooling channel with a staggered array of pin fins, the usefulness of the scaling factor, (Tw/Tb)r, from the literature for smooth ducts was examined. Nuengine, computed under engine conditions, was compared with those computed under laboratory conditions, Nulab, and scaled by (Tw/Tb)r; i.e., Nulab,scaled = Nulab (Tw/Tb)r. Results obtained show the error in Nulab,scaled relative to Nuengine can be as high as 36.6% if r = −0.7 and Tw/Tb = 1.573 in the “fully” developed region. Thus, (Tw/Tb)r based on smooth duct should not be used as a scaling factor for Nu in cooling passages with heat-transfer enhancement features. To address this inadequacy, a method is proposed for generating scaling factors, and a scaling factor was developed to scale the heat transfer from laboratory to engine conditions for a channel with pin fins.

Numerical Simulation of Evaporating Two-Phase Flow in a High-Aspect-Ratio Microchannel with Bends

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Junsik Lee ◽  
Junsub Kim ◽  
Hyungsoo Lim ◽  
Je Sung Bang ◽  
Jeong Min Seo ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Flow Visualization ◽  
Film Cooling ◽  
High Speed ◽  
National Research Council ◽  
Air Cooling ◽  
Hole Size ◽  
High Efficient ◽  
Flow Through ◽  
Effusion Hole

Effusion cooling is one of the attractive methods for next generation high-efficient gas turbine which has a very hot gas temperature above 1,600oC. For higher effectiveness of the air cooling, the air-cooled flow through effusion-holes does not penetrate into the mainstream flow but still remains within freestream boundary layer. So the air-cooled surface temperature maintains at relatively lower than film cooling. Effusion cooling is generally known as operating in small effusion-hole size which is less than 0.2 mm. This study is intended to examine optimum effusion-hole size of the microscale effusion cooling through flow visualization. The air flow through effusion-holes is visualized using an oil atomizer, a DSPP laser-sheet illumination, and a high-speed CCD imaging. The visualized results show flow patterns and characteristics with different blowing ratio, BR = ρcUc / ρ∞U∞, (BR = 0.17 and 0.53) and effusion-hole size (D = 0.2 mm, 0.5 mm and 1.0 mm). The flow visualization condition is fixed at the mainstream Reynolds number of 10,000 and hole-to-hole spacing of 4 (S/D = 4). For larger effusion-hole of 1.0 mm [(a) and (b)], the effusion flow can penetrate into boundary layer which exhibits a film cooling. However the effusion flow is observed to be remained within boundary layer which shows an effusion cooling for smaller effusion-hole of 0.2 mm [(e) and (f)]. In case of (c) and (d), a series of vortical structure is also observed to be within the boundary layer along the effusion flat plate. Note that the effusion-hole size of 0.5 mm can be a candidate for making effusion cooling possible. [This work was supported by National Research Council of Science and Technology (NST) grant funded by the Ministry of Science, ICT and Future Planning, Korea (Grant No. KIMM-NK203B).]

Transpiration Cooled Turbines

1970 ◽  
Vol 185 (1) ◽  
pp. 943-951 ◽  
Author(s):  
F. J. Bayley ◽  
A. B. Turner
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Air Cooling ◽  
Transpiration Cooling

This paper lists the steps in the development chain of air cooling for gas turbine components, and represents transpiration cooling as the ultimate method. The three modes of heat transfer involved in transpiration cooling, gas side heat transfer, coolant side heat transfer and interstitial heat transfer, are discussed separately. Finally, consideration is given to the practical problems of transpiration cooling in advanced gas turbines.

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