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Gas Turbines: Ceramics

Engine Design Strategies to Maximize Ceramic Turbine Life and Reliability

[+] Author and Article Information
Michael J. Vick1

 Vehicle Research Section, Code 5712, U.S. Naval Research Laboratory, Washington, DC 20375,michael.vick@nrl.navy.mil

Osama M. Jadaan

 155 Ottensman Hall, 1 University Plaza, Platteville, WI 53818jadaan@uwplatt.edu

Andrew A. Wereszczak

 Oak Ridge National Laboratory, 1 Bethel Valley Road, Building 4515, Oak Ridge, TN 37831-6062wereszczakaa@ornl.gov

Sung R. Choi

 Naval Air Systems Command,48066 Shaw Road, Bldg. 2188, Patuxent River, MD 20670Sung.choi1@navy.mil

Andrew L. Heyes

Mechanical Engineering Department,  Imperial College London, London SW7 2AZ, UKa.heyes@imperial.ac.uk

Keith R. Pullen

Mechanical Engineering Department,  City University London, London EC1V 0HB, UKk.pullen@city.ac.uk

Kyocera Industrial Ceramic Components, Vancouver, WA.

Honeywell Ceramic Components, Torrance, CA.

NGK Insulators Ltd., Nagoya, Japan.

Saint-Gobain Ceramics and Plastics, Northboro, MA.

Rolls-Royce Allison, Indianapolis, IN.

1

Corresponding author.

J. Eng. Gas Turbines Power 134(8), 081301 (Jun 19, 2012) (11 pages) doi:10.1115/1.4005817 History: Received April 16, 2011; Revised October 03, 2011; Published June 19, 2012; Online June 19, 2012

Ceramic turbines have long promised to enable higher fuel efficiencies by accommodating higher temperatures without cooling, yet no engines with ceramic rotors are in production today. Studies cite life, reliability, and cost obstacles, often concluding that further improvements in the materials are required. In this paper, we assume instead that the problems could be circumvented by adjusting the engine design. Detailed analyses are conducted for two key life-limiting processes, water vapor erosion and slow crack growth, seeking engine design strategies for mitigating their effects. We show that highly recuperated engines generate extremely low levels of water vapor erosion, enabling lives exceeding 10,000 hs, without environmental barrier coatings. Recuperated engines are highly efficient at low pressure ratios, making low blade speeds practical. Many ceramic demonstration engines have had design point mean blade speeds near 550 m/s. A CARES/Life analysis of an example rotor designed for about half this value indicates vast improvements in slow crack growth-limited life and reliability. Halving the blade speed also reduces foreign object damage particle kinetic energy by a factor of four. In applications requiring very high fuel efficiency that can accept a recuperator, or in short-life simple cycle engines, ceramic turbines are ready for application today.

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Copyright © 2012 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Reprinted from Ref. [11]: Equilibrium products of combustion for various fuel-air equivalence ratios ΦFA . (Note, the remainder of this paper uses the air-fuel ratio: ΦAF = 1/ΦFA .)

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Figure 2

Data from Table 3, with lower (1050 °C) and higher (1350 °C) turbine inlet temperatures for comparison. Bumps in curves reflect increments in number of turbine stages to keep blade speeds below 350 m/s.

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Figure 3

Surfaces where convection condition was applied (h = 627 W/m2 K, 1225 °C). Initial rotor temperature was 15 °C. The diameter at the blade tips is 58 mm.

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Figure 4

Thermal+centrifugal stress for the example rotor, for SN282, NT154, and mullite composite material

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Figure 5

Estimated relative production cost of various stages in the process of manufacturing a ceramic turbine component, taken from a Kyocera cost study referenced in Ref. [36]

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