Carbon/Carbon Components for Advanced Gas Turbine Engines

Author(s):  
L. Danis ◽  
S. Cruzen ◽  
W. Schimmel

A preliminary assessment of carbon/carbon fiber/matrix composites for extreme temperature limited life service in small gas turbine engines has been completed. Spin tests of available disks were conducted, along with structural design micromechanical analyses of tested specimens and conceptual variants. Many specific strength values at ambient temperatures were found higher than those of presently used metals. Since these values increase as temperatures are elevated, a significant advantage is provided over contemporary and advanced turbine wheel materials. A major advantage of C/C composite over monolithic ceramic is a relative absence of defect sensitivity, brittleness, or rapid fracture progression. Experiments and studies were conducted to provide carbon/carbon bodies with state-of-the-art oxidation and erosion protection. Silicon carbide coated specimens show required promising static oxidation resistance for target engine mission life. Simulated dynamic end use tests have yet to be completed. It is recommended that further programs on carbon/carbon composite turbine components be conducted immediately to address coating refinement, component design, development of appropriate fiber architecture, and characterization of those architectures which result in acceptable service properties on tested components.

Author(s):  
P. A. Phillips ◽  
Peter Spear

After briefly summarizing worldwide automotive gas turbine activity, the paper analyses the power plant requirements of a wide range of vehicle applications in order to formulate the design criteria for acceptable vehicle gas turbines. Ample data are available on the thermodynamic merits of various gas turbine cycles; however, the low cost of its piston engine competitor tends to eliminate all but the simplest cycles from vehicle gas turbine considerations. In order to improve the part load fuel economy, some complexity is inevitable, but this is limited to the addition of a glass ceramic regenerator in the 150 b.h.p. engine which is described in some detail. The alternative further complications necessary to achieve satisfactory vehicle response at various power/weight ratios are examined. Further improvement in engine performance will come by increasing the maximum cycle temperature. This can be achieved at lower cost by the extension of the use of ceramics. The paper is intended to stimulate the design application of the gas turbine engine.


2011 ◽  
Vol 230-232 ◽  
pp. 1123-1128
Author(s):  
Yu Wang ◽  
Zhen Luo

Small gas turbine engines have been considered as a potential and popular mean of propulsion for Unmanned Aerial Vehicles (UAV). With the advantage of high thrust/power-to-weight-ratio from these engines, small aircraft can have larger payload allowance and higher altitude capability. However, at present, these gas turbine engines are not mature enough to perform critical mission for UAV. To be used for such critical mission, these gas turbine engines need a better reliability, efficiency and endurance. The capability of the engine to work efficiently in conditions at different altitude with the variant of air density is a critical factor related to higher operational ceiling. Hence this work aims to present a Computational Fluid Dynamics (CFD) simulation approach focusing on centrifugal compressors which are applied to turbo machines. A computational method is developed for studying the performance of small gas turbine engines over a range of altitude and ambient temperatures under different engine rates, and a centrifugal compressor simulation model is generated by using CFD techniques. Through numerical solutions obtained for different mesh sets the finest mesh of the model was determined. The performance curves obtained by the CFD simulation has been compared with the results obtained from the analytical method.


Author(s):  
M. A. Alvin ◽  
B. Gleeson ◽  
K. Klotz ◽  
B. McMordie ◽  
B. Warnes ◽  
...  

The National Energy Technology Laboratory-Regional University Alliance (NETL-RUA) has been developing extreme temperature coating systems that consist of a diffusion barrier coating (DBC), a low-cost wet slurry bond coat, a commercial yttria stabilized zirconia (YSZ) thermal barrier coating (TBC), and an extreme temperature external coating that are deposited along the surface of nickel-based superalloys and single crystal metal substrates. Thermal cyclic testing of these multi-layer coatings was conducted in steam-containing environments at temperatures ranging between 1100–1550°C. This paper discusses the response of these materials during bench-scale testing, and their potential use in advanced H- and J-class land-based gas turbine engines.


Author(s):  
Michael J. L. Percival ◽  
Colin P. Beesley

Currently available Ceramic Matrix Composites (CMCs) have very low stress carrying capability if they are to achieve the service life required for application in gas turbine engines. As such, they are most likely to find their first applications in non-structural components with low mechanical loads, where the majority of the stress is thermally induced. The thermal cycling experienced in gas turbine engines, coupled with the necessary interfaces with surrounding metal components and other geometric features, means that these thermal stresses are often localised, but in order to produce a valid component design they may significantly exceed the maximum design stress. The aim of this paper is to discuss the implications for the life of the component of these excess stresses. This will cover the mechanisms for the propagation of localised damage in a strain controlled environment, and the effect of this damage on the thermal conductivity and hence on the induced thermal gradients and thermal strains. Strains corresponding to stresses considerably above the normally accepted design stress can be sustained for a considerable number of cycles, but the influence of extended time periods with damage at elevated temperatures remains unexplored.


Author(s):  
Mustapha Chaker ◽  
Cyrus B. Meher-Homji

There are numerous power generation and mechanical drive gas turbine applications where the power drop caused by high ambient temperatures has a very detrimental effect on the production of power or process throughput. Media evaporative cooling and inlet fogging are common low cost power augmentation techniques applied to reduce these losses. Several misconceptions exist regarding the applicability of evaporative cooling to what are often called “high humidity” regions. There is a sizable evaporative cooling potential in most locations when climatic data is evaluated based on an analysis of coincident wet bulb and dry bulb data. This data is not readily available to plant users and designers. This paper provides a detailed treatment of available climatic data bases and presents actual climatic data from several world wide locations to show that considerable cooling potential actually exists even in high humidity regions. It is hoped that this paper will be of value to plant designers, engineering and operating companies that are considering the use of evaporative cooling for power augmentation.


Author(s):  
M. A. Alvin ◽  
K. Klotz ◽  
B. McMordie ◽  
D. Zhu ◽  
B. Gleeson ◽  
...  

The National Energy Technology Laboratory-Regional University Alliance (NETL-RUA) has been developing extreme temperature coating systems that consist of a diffusion barrier coating (DBC), a low-cost wet slurry bond coat, a commercial yttria stabilized zirconia (YSZ) thermal barrier coating (TBC), and an extreme temperature external coating that are deposited along the surface of nickel-based superalloys and single crystal metal substrates. Thermal cyclic testing of these multilayer coatings was conducted in steam-containing environments at temperatures ranging between 1100 and 1550 °C. This paper discusses the response of these materials during bench-scale testing, and their potential use in advanced H- and J-class land-based gas turbine engines.


Author(s):  
Y. Otsuki ◽  
Y. Nishihara ◽  
E. Ito ◽  
A. Hoshino ◽  
I. Inobe

Since 1972, Kawasaki Heavy Industries, Ltd., in Japan has been promoting development of a series of smaller size industrial gas turbine engines. Kawasaki now has eight models of their own gas turbines in production. These models, which include increased power types and twin types, consist of three base series ranging in output power from 260 PS to 4,000 PS. All of these engine models were successfully completed in a short period with the aid of the scale-up and -down design development method. They are assembled as a prime mover into a series of Kawasaki gas turbine generator sets. A bout 360 units are now in service with a large variety of customers. This paper gives a general description of these Kawasaki development industrial gas turbines with some of the features highlighted.


Author(s):  
Alan H. Epstein

The confluence of market demand for greatly improved compact power sources for portable electronics with the rapidly expanding capability of micromachining technology has made feasible the development of gas turbines in the millimeter-size range. With airfoil spans measured in 100’s of microns rather than meters, these “microengines” have about 1 millionth the air flow of large gas turbines and thus should produce about 1 millionth the power, 10–100 W. Based on semiconductor industry-derived processing of materials such as silicon and silicon carbide to submicron accuracy, such devices are known as micro-electro-mechanical systems (MEMS). Current millimeter-scale designs use centrifugal turbomachinery with pressure ratios in the range of 2:1 to 4:1 and turbine inlet temperatures of 1200–1600 K. The projected performance of these engines are on a par with gas turbines of the 1940’s. The thermodynamics of MEMS gas turbines are the same as those for large engines but the mechanics differ due to scaling considerations and manufacturing constraints. The principal challenge is to arrive at a design which meets the thermodynamic and component functional requirements while staying within the realm of realizable micromachining technology. This paper reviews the state-of-the-art of millimeter-size gas turbine engines, including system design and integration, manufacturing, materials, component design, accessories, applications, and economics. It discusses the underlying technical issues, reviews current design approaches, and discusses future development and applications.


1997 ◽  
Vol 28 (7-8) ◽  
pp. 536-542
Author(s):  
A. A. Khalatov ◽  
I. S. Varganov

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