Impingement Cooling in Gas Turbines: Design, Applications, and Limitations

The thermoacoustic stability of gas turbines depends on a balance of acoustic energy inside the engine. While the flames produce acoustic energy, other areas like the impingement cooling system contribute to damping. In this paper, we investigate the damping potential of an annular impingement sleeve geometry embedded into a realistic environment. A cold flow test rig was designed to represent real engine conditions in terms of geometry, and flow situation. High quality data was delivered by six piezoelectric dynamic pressure sensors. Experiments were carried out for different mean flow velocities through the cooling holes. The acoustic reflection coefficient of the impingement sleeve was evaluated at a downstream reference location. Further parameters investigated were the number of cooling holes, and the geometry of the chamber surrounding the impingement sleeve. Experimental results show that the determining parameter for the reflection coefficient is the mean flow velocity through the impingement holes. An increase of the mean flow velocity leads to significantly increased damping, and to low values of the reflection coefficient.

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Pulsed Impingement Turbine Cooling and its Effect on the Efficiency of Gas Turbines With Pressure Gain Combustion

Volume 7A: Heat Transfer ◽

10.1115/gt2020-15344 ◽

2020 ◽

Author(s):

Nicolai Neumann ◽

Dieter Peitsch ◽

Arne Berthold ◽

Frank Haucke ◽

Panagiotis Stathopoulos

Keyword(s):

Gas Turbine ◽

Thermal Efficiency ◽

Gas Turbines ◽

Turbine Blades ◽

Impingement Cooling ◽

Turbine Cooling ◽

Pressure Gain Combustion ◽

Cooling Air ◽

Gas Turbine Cycle ◽

Cycle Efficiency

Abstract Performance improvements of conventional gas turbines are becoming increasingly difficult and costly to achieve. Pressure Gain Combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycle. Previous cycle analyses considering turbine cooling methods have shown that the application of pressure gain combustion may require more turbine cooling air. This has a direct impact on the cycle efficiency and reduces the possible efficiency gain that can potentially be harvested from the new combustion technology. Novel cooling techniques could unlock an existing potential for a further increase in efficiency. Such a novel turbine cooling approach is the application of pulsed impingement jets inside the turbine blades. In the first part of this paper, results of pulsed impingement cooling experiments on a curved plate are presented. The potential of this novel cooling approach to increase the convective heat transfer in the inner side of turbine blades is quantified. The second part of this paper presents a gas turbine cycle analysis where the improved cooling approach is incorporated in the cooling air calculation. The effect of pulsed impingement cooling on the overall cycle efficiency is shown for both Joule and PGC cycles. In contrast to the authors’ anticipation, the results suggest that for relevant thermodynamic cycles pulsed impingement cooling increases the thermal efficiency of Joule cycles more significantly than it does in the case of PGC cycles. Thermal efficiency improvements of 1.0 p.p. for pure convective cooling and 0.5 p.p. for combined convective and film with TBC are observed for Joule cycles. But just up to 0.5 p.p. for pure convective cooling and 0.3 p.p. for combined convective and film cooling with TBC are recorded for PGC cycles.

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The Mass Transfer Analogy to Heat Transfer in Fluids With Temperature-Dependent Properties

Journal of Turbomachinery ◽

10.1115/1.2927734 ◽

1991 ◽

Vol 113 (1) ◽

pp. 27-33 ◽

Cited By ~ 25

Author(s):

J. N. Shadid ◽

E. R. G. Eckert

Keyword(s):

Heat Transfer ◽

Mass Transfer ◽

Film Cooling ◽

Gas Turbines ◽

Transport Processes ◽

Constant Property ◽

Impingement Cooling ◽

Fluid Properties ◽

Temperature Dependent Properties ◽

Isothermal Mass

The analogy between heat transfer in a single-component fluid and isothermal mass transfer of a two-component fluid without chemical reaction is presented. The analogy is well established and frequently used for fluids with constant properties. However, in various applications such as in the cooling of hot components in gas turbines, the temperature varies widely, causing significant fluid property variations. The present paper reviews the constant-property situation and considers in detail the conditions necessary to ensure similarity of the two transport processes with temperature and concentration-dependent fluid properties. An application of the variable property analogy to mass transfer in binary mixtures is presented along with specific recommendations for the CO2–air and Freon-air systems. It is demonstrated that the essential similarity conditions of the analogy are very well fulfilled for film cooling, total coverage film cooling, and impingement cooling when the heat (mass) flux into the wall in the transport process is zero. The heat/mass transfer analogy can, therefore, be used with confidence for these processes.

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The Advanced Cooling Technology for the 1500°C Class Gas Turbines: Steam-Cooled Vanes and Air-Cooled Blades

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2817030 ◽

1997 ◽

Vol 119 (3) ◽

pp. 624-632 ◽

Cited By ~ 25

Author(s):

H. Nomoto ◽

A. Koga ◽

S. Ito ◽

Y. Fukuyama ◽

F. Otomo ◽

...

Keyword(s):

Wind Tunnel ◽

Electric Power ◽

Gas Turbine ◽

Film Cooling ◽

Gas Turbines ◽

Combined Cycle ◽

Cooling Effectiveness ◽

Impingement Cooling ◽

Cycle Systems ◽

Cooling Technology

It is very essential to raise the thermal efficiency of combined cycle plants from the viewpoint of energy saving and environmental protection. Tohoku Electric Power Co., Inc., and Toshiba Corporation in Japan have jointly studied the next generation of combined cycle systems using 1500°C class gas turbine. A promising cooling technology for the vanes using steam was developed. The blades are cooled by air, adopting the impingement cooling, film cooling, and so on. The cooling effectiveness was confirmed both for the vanes and the blades using a hot wind tunnel. This paper describes the design features of the vanes and the blades, and the results of the verification tests using the hot wind tunnel.

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Experimental Investigation of Impingement Cooling With Turbulators or Surface Enlarging Elements

Volume 3: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/2001-gt-0149 ◽

2001 ◽

Cited By ~ 16

Author(s):

Mats O. Annerfeldt ◽

Johan L. Persson ◽

Tord Torisson

Keyword(s):

Nusselt Number ◽

Flat Plate ◽

Heat Conductivity ◽

Gas Turbines ◽

Infrared Camera ◽

Pumping Power ◽

Impingement Cooling ◽

Base Area ◽

Enhancement Factors ◽

Plate Distance

For the materials in modern gas turbines to survive, a considerable amount of cooling is required. In cases where large amounts of heat need to be removed, impingement cooling with its high heat transfer coefficients may be a good alternative. The possibilities of enhancing impingement cooling by introducing surface enlarging/turbulence enhancing elements are examined experimentally in this work. A technique using thin foil heaters combined with an infrared camera is used. Local temperature distribution on the target plate is measured, enabeling to separately evaluate the Nusselt number enhancement for different areas. Experiments are conducted for four different area enlarging geometries: triangle, wing, cylinder and dashed rib all made from aluminum. Comparison between each area enlarged surface and a flat plate is made in terms of Nusselt number and also pumping power in order to maximize the cooling efficiency. Overall Nusselt number enhancement factors compared to impingement on a flat plate show values of 1 to 1.3, the trend decreasing with increased jet-to-plate distance and Reynolds number. When normalizing by the spent pumping power the enhancement factors drop to 0.4 to 1.2 compared to impingement on a smooth plate. The best results were achieved with die rib geometry and when not using a too large value of enlarger height compared to jet-to-plate distance. Row-wise evaluation of Nusselt number enhancement shows an increased enhancement factor with row number and therefore crossflow ratio (Gc/Gj). The infrared camera pictures reveal that the enhancement is found in three different areas, on the enlarger base area, the area just downstream the enlarger and in diagonal streaks with increased turbulence generated by the enlargers. Tests using an enlarger material with heat conductivity scaled to represent actual gas turbine conditions show that only the enlarger base area is affected when decreasing the enlarger heat conductivity. The result is a small decrease in total Nusselt number enhancement.

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Pulsed Impingement Turbine Cooling and Its Effect on the Efficiency of Gas Turbines With Pressure Gain Combustion

Journal of Turbomachinery ◽

10.1115/1.4050361 ◽

2021 ◽

Vol 143 (7) ◽

Author(s):

Nicolai Neumann ◽

Arne Berthold ◽

Frank Haucke ◽

Dieter Peitsch ◽

Panagiotis Stathopoulos

Keyword(s):

Gas Turbine ◽

Thermal Efficiency ◽

Gas Turbines ◽

Turbine Blades ◽

Impingement Cooling ◽

Turbine Cooling ◽

Pressure Gain Combustion ◽

Cooling Air ◽

Gas Turbine Cycle ◽

Cycle Efficiency

Abstract Performance improvements of conventional gas turbines are becoming increasingly difficult and costly to achieve. Pressure gain combustion (PGC) has emerged as a promising technology in this respect, due to the higher thermal efficiency of the respective ideal gas turbine cycle. Previous cycle analyses considering turbine cooling methods have shown that the application of pressure gain combustion may require more turbine cooling air. This has a direct impact on the cycle efficiency and reduces the possible efficiency gain that can potentially be harvested from the new combustion technology. Novel cooling techniques could unlock an existing potential for a further increase in efficiency. Such a novel turbine cooling approach is the application of pulsed impingement jets inside the turbine blades. In the first part of this paper, results of pulsed impingement cooling experiments on a curved plate are presented. The potential of this novel cooling approach to increase the convective heat transfer in the inner side of turbine blades is quantified. The second part of this paper presents a gas turbine cycle analysis where the improved cooling approach is incorporated in the cooling air calculation. The effect of pulsed impingement cooling on the overall cycle efficiency is shown for both Joule and PGC cycles. In contrast to the authors’ anticipation, the results suggest that for relevant thermodynamic cycles pulsed impingement cooling increases the thermal efficiency of Joule cycles more significantly than it does in the case of PGC cycles. Thermal efficiency improvements of 1.0 p.p. for pure convective cooling and 0.5 p.p. for combined convective and film with TBC are observed for Joule cycles. But just up to 0.5 p.p. for pure convective cooling and 0.3 p.p. for combined convective and film cooling with TBC are recorded for PGC cycles.

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Jet Impingement Cooling in Gas Turbines for Improving Thermal Efficiency and Power Density

Advances in Gas Turbine Technology ◽

10.5772/22020 ◽

2011 ◽

Cited By ~ 1

Author(s):

Luai M. ◽

S.M. Shaahid ◽

Ali A.

Keyword(s):

Power Density ◽

Thermal Efficiency ◽

Gas Turbines ◽

Jet Impingement ◽

Impingement Cooling

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The Advanced Cooling Technology for the 1500 °C Class Gas Turbines: The Steam Cooled Vanes and the Air Cooled Blades

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration ◽

10.1115/96-gt-016 ◽

1996 ◽

Author(s):

H. Nomoto ◽

A. Koga ◽

S. Ito ◽

Y. Fukuyama ◽

F. Otomo ◽

...

Keyword(s):

Wind Tunnel ◽

Electric Power ◽

Gas Turbine ◽

Film Cooling ◽

Gas Turbines ◽

Combined Cycle ◽

Cooling Effectiveness ◽

Impingement Cooling ◽

Cycle System ◽

Cooling Technology

It is very essential to raise the thermal efficiency of combined cycle plants from the viewpoint of energy saving and environmental protection. Tohoku Electric Power Co., Inc. and Toshiba Corporation in Japan have jointly studied the next generation of combined cycle system using 1500 °C class gas turbine. A promising cooling technology for the vanes using steam was developed. The blades are cooled by air, adopting the impingement cooling, the film cooling and so on. The cooling effectiveness was confirmed both for the vanes and the blades using hot wind tunnel. This paper describes the design features of the vanes and the blades, and the results of the verification tests using hot wind tunnel.

Download Full-text