Closure to “Discussion of ‘Experimental Investigation of Film Cooling With Ejection From a Row of Holes for the Application to Gas Turbine Blades’” (1975, ASME J. Eng. Power, 97, p. 27)

1975 ◽  
Vol 97 (1) ◽  
pp. 27-27
Author(s):  
C. Liess
Keyword(s):  
Experimental Investigation ◽  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Gas Turbine Blades

Film Cooling of Gas Turbine Blades: A Study of the Effect of Large Temperature Differences on Film Cooling Effectiveness

1977 ◽  
Vol 99 (1) ◽  
pp. 11-20 ◽  
Author(s):  
M. A. Paradis
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Large Temperature ◽  
Constant Property ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Gas Turbine Blades ◽  
Combustion Gases ◽  
Simple Equations

Experiments have been performed on the film cooling of gas turbine blades in order to study the influence of large temperature differences on the effectiveness of film cooling. A two-dimensional flat plate model was tested in a stream of 1000 K combustion gases flowing at between 110 and 170 m/s. The model was cooled on both sides by jets of air coming from flush angled slots. The range of velocity ratios Uc/Ug covered was from 0.3 to 1.7 and the range of blowing rates was between 0.5 and 5. Film cooling effectiveness was measured and boundary layer traverses were performed. It has been found that once radiation and conduction effects are taken into account, the simple equations proposed by previous workers for the constant property case could be used with little error.

AERODYNAMICS AND HEAT TRANSFER INSIDE A GAS TURBINE MID-PASSAGE GAP

2021 ◽  
pp. 1-13
Author(s):  
Faisal Shaikh ◽  
Budimir Rosic
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Film Cooling ◽  
Heat Load ◽  
Turbine Blades ◽  
Turbine Stage ◽  
Gas Turbine Blades ◽  
Cooling Flows ◽  
Turbine Efficiency ◽  
Gap Flow

Abstract Gas turbine blades and vanes are typically manufactured with small clearances between adjacent vane and blade platforms, termed the midpassage gap. The midpassage gap reduces turbine efficiency and causes additional heat load into the vane platform, as well as changing the distribution of endwall heat transfer and film cooling. This paper presents a low-order analytical analysis to quantify the effects of the midpassage gap on aerodynamics and heat transfer, verified against an experimental campaign and CFD. Using this model, the effects of the gap can be quantified, for a generic turbine stage, based only on geometric features and the passage static pressure field. It is found that at present there are significant losses and a large proportion of heat load caused by the gap, but that with modified design this could be reduced to negligible levels. Cooling flows into the gap to prevent ingression are investigated analytically and with CFD. Recommendations are given for targets that turbine designers should work toward in reducing the adverse effects of the midpassage gap. A method to estimate the effect of gap flow is presented, so that for any machine the significance of the gap may be assessed.

High-Pressure Gas Turbine Vane Turbulent Flows and Heat Transfer Predicted by RANS/LES/DES

2017 ◽  
Author(s):  
Ping Dong ◽  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Gas Turbine ◽  
Turbulent Flows ◽  
Film Cooling ◽  
Turbine Blades ◽  
Suction Side ◽  
Gas Turbine Blades ◽  
Flow And Heat Transfer ◽  
Turbine Vane

The lifetime of the modern gas turbines greatly depends on the durability of hot section components operating at high temperatures. Film cooling is key to air cooling technologies in modern gas turbine and widely used in high-temperature and high-pressure blades as an active cooling scheme. The requirements of accurate prediction of aerodynamic flow and heat transfer in gas turbine blades lay the essential foundation of cooling effectiveness improvement and working life estimation. In recent days, Large Eddy Simulations (LES) is considered as a useful tool to predict turbulent flows and heat transfer around gas turbine blades, but, comparing to the Reynolds-Averaged Navier–Stokes (RANS) methods, the LES method usually needs more computing resource and depends on computational power and mesh quality. In this paper, LES/DES (Detached Eddy Simulation) predictions were compared to RANS prediction with interest in the accuracy and improvement of turbulent flow and heat transfer phenomena around NASA’s C3X high-pressure gas turbine vane with leading edge cooling film. RANS/LES/DES were detailed and further investigated to assess their ability to predict flow and heat transfer in boundary layer around C3X vane. The current predictions showed that the mix between film cooling injections and free stream resulted in complex flow and heat transfer in the boundary layer on the external vane surface. The predictions of the aerodynamic load along the C3X vane with RANS/LES/DES were almost identical and agreed well with the experimental results. However, the heat transfer predictions with RANS/LES/DES were different. The transition prediction showed the best agreement with the experiment data in the most region. The LES prediction only partially agreed with the experimental data before separation point on the suction side and mild pressure gradient region on the pressure side. The DES and RANS predictions agreed with the experiment data after separation point on the suction side and most region on the pressure side.

Simulation of Mist Film Cooling on Rotating Gas Turbine Blades

2009 ◽  
Author(s):  
T. S. Dhanasekaran ◽  
Ting Wang
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Inlet Temperature ◽  
Single Pair ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Gas Turbine Blades ◽  
Cooling Enhancement ◽  
Mist Cooling

Film cooling technique has been successfully applied to gas turbine blades to prevent it from the hot flue gas. However, a continuous demand of increasing the turbine inlet temperature to raise the efficiency of the turbine requires continuous improvement in film cooling effectiveness. The concept of injecting mist (tiny water droplets) into the cooling fluid has been proven under laboratory conditions to significantly augment adiabatic cooling effectiveness 50–800% in convective heat transfer and impingement cooling. The similar concept of ejecting mist into air film cooling has not been proven in the laboratory, but computational simulation has been performed on stationary turbine blades. As a continuation of previous research, this paper extends the mist film cooling scheme to the rotating turbine blade. For the convenience of understanding the effect of rotation, the simulation is first conducted with a single pair of cooling hole located near the leading edge at either side of the blade. Then a row of multiple-hole film cooling jets are simulated at stationary and rotational condition. Operating condition under both the laboratory (baseline) and elevated gas turbine conditions are simulated and compared. The effects of various parameters including mist concentration, water droplet diameter, droplet wall boundary condition, blowing ratio, and rotational speed are investigated. The results showed the effect of rotation on droplets at lab condition is minimal. The CFD model employed the Discrete Phase Model (DPM) including both wall film and droplet reflect conditions. The results showed that the droplet-wall interaction is stronger on the pressure side than on the suction side resulting in a higher mist cooling enhancement on the pressure side. The average mist cooling enhancement of about 15% and 35% are achieved on the laboratory and elevated conditions, respectively. This translates into a significant blade surface temperature reduction of 100–125 K with 10% mist injection at elevated condition.

Novel Focal Sweep Strategy for Optical Aerothermal Measurements of Film-Cooled Gas Turbine Blades With Highly Inclined Viewing Angle

2021 ◽  
Vol 144 (3) ◽  
Author(s):  
Hongyi Shao ◽  
Xu Zhang ◽  
Di Peng ◽  
Yingzheng Liu ◽  
Wenwu Zhou ◽  
...  
Keyword(s):  
3D Reconstruction ◽  
Flat Plate ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Turbine Blades ◽  
Viewing Angle ◽  
Sweep Method ◽  
Gas Turbine Blades ◽  
3D Point Clouds

Abstract The viewing angle for optical aerothermal measurements on turbine surfaces is often limited by the turbine structure, requiring the optical system to have a large depth of field (DoF). Although the DoF can be increased by decreasing the lens aperture, this approach is impractical as a large aperture is essential to maintain an acceptable signal-to-noise ratio (SNR). To solve these problems in the optical aerothermal measurements of film-cooled gas turbine blades, an approach combining the focal-sweep method and three-dimensional (3D) reconstruction is proposed. The focal-sweep method is used to obtain all-in-focus images at an inclined viewing angle, following which the two-dimensional image is restored through 3D reconstruction. Thus, 3D point clouds with both a large DoF and high SNR can be produced. The developed method was validated via flat-plate film cooling experiments using pressure-sensitive paint at three blowing ratios of 0.4, 0.8, and 1.2, as well as three viewing angles. The measured adiabatic effectiveness contours demonstrate that the proposed method can produce all-in-focus measurements at highly inclined viewing angles, albeit at the price of slightly higher noise. In flat-plate experiments, the maximum relative difference is measured to be 6% between results obtained by conventional method at normal view and the proposed method at highly inclined view. Furthermore, the proposed method was applied to the turbine blade cascade film cooling experiment at a highly inclined viewing angle, and successfully reconstructed the 3D point cloud of the cooling effectiveness at the curved turbine blade surface.

The Use of Compound Cooling Holes for Film Cooling at the End Wall of Combustor Simulator

2014 ◽  
Vol 695 ◽  
pp. 371-375
Author(s):  
Nor Azwadi Che Sidik ◽  
Shahin Salimi
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Gas Turbine Blades ◽  
Turbine Cooling ◽  
Cooling Flow ◽  
Cooling Method ◽  
External Cooling ◽  
Cylindrical Holes

Gas turbine cooling can be classified into two different schemes; internal and external cooling. In internal cooling method, the coolant provided by compressor is forced into the cooling flow circuits inside turbine components. Meanwhile, for the external cooling method, the injected coolant is directly perfused from coolant manifold to save downstream components against hot gases. Furthermore, in the latter coolant scheme, coolant is used to quell the heat transfer from hot gas stream to a component. There are several ways in external cooling. Film cooling is one of the best cooling systems for the application on gas turbine blades. This study concentrates on the comparison of experimental, computational and numerical investigations of advanced film cooling performance for cylindrical holes at different angles and different blowing ratios in modern turbine gas.

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