Investigation of Vanadium Carbide Reinforced CMC for Gas Turbine Stator

2018 ◽  
Author(s):  
S. Ram Kumar ◽  
Vikram Ramanan
Keyword(s):  
Silicon Carbide ◽  
High Pressure ◽  
Gas Turbine ◽  
Vanadium Carbide ◽  
Elevated Temperatures ◽  
Ceramic Matrix Composites ◽  
Structural Aspect ◽  
Inlet Temperature ◽  
Melting Points ◽  
Turbine Stator

Gas turbine, or the jet engines have seen a rise in thrust output by increasing the chamber temperatures, advancement in compressor staging etc. On due of increased temperature limits, the turbine has particularly been subjected to higher thermomechanical stresses on the first stage high pressure stators, caused by the hot combustion product gases at high velocities. Thermal strains also get induced due to non-uniform temperature distribution from the hub to tip of the vanes. Improvements in material technologies to curb for higher temperatures have brought ceramic matrix composites into implementation. These are lighter in weight and have higher melting points than the conventionally used metal super alloys, with silicon carbide SiC/SiC matrix being specially used as the material for turbine stage of the engine. This consists of long unidirectional sic fibers as reinforcement, embedded in sic matrix phase, with fibre volume fractions in the range 30–40 percentages. But with further increase in thrust requirements, the turbine inlet temperature is also increased, affecting the material and the performance life of the component. Hence furthermore innovation in materials with higher strengths and melting points has to be incorporated. This work is on the use of vanadium carbide fibers as the reinforcement phase of silicon carbide matrix composite for the high pressure turbine stator. Structural analysis is carried out for the blade for both the composites, in ansys software using time stepped increment in temperature upto 1600°c. Results are compared to that for Sic/Sic composites. Thus the comparative analysis between the two composites is carried out on the thermo-structural aspect to predict their performance in the elevated temperatures.

Application of Ultra-Low NOx Combustor to the MHPS Existing Gas Turbine

2021 ◽  
Author(s):  
Takashi Nishiumi ◽  
Hirofumi Ohara ◽  
Kotaro Miyauchi ◽  
Sosuke Nakamura ◽  
Toshishige Ai ◽  
...  
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Operational Experience ◽  
Emission Rates ◽  
Gas Temperature ◽  
Design Development ◽  
And Control

Abstract In recent years, MHPS achieved a NET M501J gas turbine combined cycle (GTCC) efficiency in excess of 62% operating at 1,600°C, while maintaining NOx under 25ppm. Taking advantage of our gas turbine combustion design, development and operational experience, retrofits of earlier generation gas turbines have been successfully applied and will be described in this paper. One example of the latest J-Series technologies, a conventional pilot nozzle was changed to a premix type pilot nozzle for low emission. The technology was retrofitted to the existing F-Series gas turbines, which resulted in emission rates of lower than 9ppm NOx(15%O2) while maintaining the same Turbine Inlet Temperature (TIT: Average Gas Temperature at the exit of the transition piece). After performing retrofitting design, high pressure rig tests, the field test prior to commercial operation was conducted on January 2019. This paper describes the Ultra-Low NOx combustor design features, retrofit design, high pressure rig test and verification test results of the upgraded M501F gas turbine. In addition, it describes another upgrade of turbine to improve efficiency and of combustion control system to achieve low emissions. Furthermore it describes the trouble-free upgrade of seven (7) units, which was completed by utilizing MHPS integration capabilities, including handling all the design, construction and service work of the main equipment, plant and control systems.

Engine Test Experience and Characterization of Self Sealing Ceramic Matrix Composites for Nozzle Applications in Gas Turbine Engines

2003 ◽  
Author(s):  
Eric P. Bouillon ◽  
Patrick C. Spriet ◽  
Georges Habarou ◽  
Thibault Arnold ◽  
Greg C. Ojard ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Elevated Temperatures ◽  
Low Cycle Fatigue ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Turbine Engines ◽  
Matrix Composites ◽  
Gas Turbine Engines ◽  
Sic Fiber ◽  
Engine Testing

Advanced materials are targeting durability improvement in gas turbine engines. One general area of concern for durability is in the hot section components of the engine. Ceramic matrix composites offer improvements in durability at elevated temperatures with a corresponding reduction in weight for nozzles of gas turbine engines. Building on past material efforts, ceramic matrix composites using a carbon and a SiC fiber with a self-sealing matrix have been developed for gas turbine applications. Prior to ground engine testing, a reduced test matrix was undertaken to aggressively test the material in a long-term hold cycle at elevated temperatures and environments. This tensile low cycle fatigue testing was done in air and a 90% steam environment. After completion of the aggressive testing effort, six nozzle seals were fabricated and installed in an F100-PW-229 engine for accelerated mission testing. The C fiber CMC and the SiC Fiber CMC were respectively tested to 600 and 1000 hours in accelerated conditions without damage. Engine testing is continuing to gain additional time and insight with the objective of pursuing the next phase of field service evaluation. Mechanical testing and post-test characterization results of this testing will be presented. The results of the engine testing will be shown and overall conclusions drawn.

An Experimental Study of Combustor Exit Profile Shapes on Endwall Heat Transfer in High Pressure Turbine Vanes

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
M. D. Barringer ◽  
K. A. Thole ◽  
M. D. Polanka
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Elevated Temperatures ◽  
Convection Heat Transfer ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Transfer Coefficients ◽  
High Pressure Turbine ◽  
Radial Profiles ◽  
Temperature And Pressure

The design and development of current and future gas turbine engines for aircraft propulsion have focused on operating the high pressure turbine at increasingly elevated temperatures and pressures. The drive toward thermal operating conditions near theoretical stoichiometric limits as well as increasingly stringent requirements on reducing harmful emissions both equate to the temperature profiles exiting combustors and entering turbines becoming less peaked than in the past. This drive has placed emphasis on determining how different types of inlet temperature and pressure profiles affect the first stage airfoil endwalls. The goal of the current study was to investigate how different radial profiles of temperature and pressure affect the heat transfer along the vane endwall in a high pressure turbine. Testing was performed in the Turbine Research Facility located at the Air Force Research Laboratory using an inlet profile generator. Results indicate that the convection heat transfer coefficients are influenced by both the inlet pressure profile shape and the location along the endwall. The heat transfer driving temperature for inlet profiles that are nonuniform in temperature is also discussed.

Brush Seals for the No. 3 Bearing of a Model 7EA Gas Turbine

2000 ◽  
Author(s):  
Steve Ingistov ◽  
Gary Meredith ◽  
Erik Sulda
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Elevated Temperatures ◽  
Axial Compressor ◽  
Lubricating Oil ◽  
Additional Element ◽  
The Third ◽  
Air Stream ◽  
Brush Seals

Gas Turbines in power generation are frequently of the single rotor type. The rotor is directly connected to the electrical generator. The rotor may be supported by two journal bearings or in some cases there is an additional journal bearing situated between the axial compressor discharge and the gas turbine intake. This third bearing serves to provide the rotor with additional support required to reduce rotor dynamic instabilities. The third bearing is, therefore, inside the machine housing and a significant amount of maintenance work is necessary to inspect it. The third bearing is also exposed to elevated temperatures by, essentially, being surrounded by compressor discharge air. A certain amount of compressor discharge air leaks through the seals into the cylindrical space around the third bearing housing and from there, due to significant pressure gradients, into the third bearing. Labyrinth seals are provided to impede air leakage from the pressurized cylindrical space into the bearing cavity. The air that leaks into the bearing housing mixes with a buffer air stream. This buffer air stream serves to cool the bearing cavity and to prevent leakage of hot, high-pressure air into the bearing cavity. Two dry air streams are then routed into the atmosphere via the coaxial space formed by two cylindrical surfaces. The portion of the buffer air stream contacting the bearing lubricating oil is de-misted in a special de-mister vessel. The de-misted air is exhausted into the atmosphere and the separated oil is returned to the gas turbine lubricating oil reservoir. This Paper discusses the introduction of brush seals into the No. 3 bearing housing as an additional element in retarding the high pressure, high temperature air infiltration into the No. 3 bearing housing.

scholarly journals Thermal Strains and Their Effect on the Life of Ceramic Matrix Composite Components in Gas Turbine Engines

1996 ◽  
Author(s):  
Michael J. L. Percival ◽  
Colin P. Beesley
Keyword(s):  
Gas Turbine ◽  
Thermal Stresses ◽  
Elevated Temperatures ◽  
Ceramic Matrix Composite ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Component Design ◽  
Design Stress

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.

Performance of a Novel Combined Cooling and Power Gas Turbine With Water Harvesting

2004 ◽  
Author(s):  
J. R. Khan ◽  
W. E. Lear ◽  
S. A. Sherif
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Inlet Temperature ◽  
Absorption Refrigeration ◽  
Ambient Conditions ◽  
Turbine Inlet Temperature ◽  
Refrigeration Unit ◽  
Vapor Absorption ◽  
Vapor Absorption Refrigeration ◽  
Pressure Compressor

A thermodynamic performance analysis is performed on a novel cooling and power cycle that combines a semi-closed cycle gas turbine called the High Pressure Regenerative Turbine Engine (HPRTE) with an absorption refrigeration unit. Waste heat from the recirculated combustion gas of the HPRTE is used to power the absorption refrigeration unit, which cools the high-pressure compressor inlet of the HPRTE to below ambient conditions and also produces excess refrigeration, in an amount which depends on ambient conditions. The cycle is modeled using traditional one-dimensional steady-state thermodynamics, with state-of-the-art polytropic efficiencies and pressure drops for the turbo-machinery and heat exchangers, and accurate y correlations for the properties of the LiBr-water mixture and the combustion products. Water produced as a product of combustion is intentionally condensed in the evaporator of the vapor absorption refrigeration system. The mixture properties of air account for the water removal rate. The vapor absorption refrigeration unit is designed to provide sufficient cooling for water extraction. The cycle is shown to operate with a thermal efficiency approaching 58% for a turbine inlet temperature of 1400 °C in addition to producing about 0.45 liters of water per liter of fuel consumed. Also at the above operating condition the ratio of the refrigeration effect to the net work output from the system is equal to 0.8. The ratio of mass of water extracted to the mass of fresh air inlet into the combined cycle is obtained for different values of cycle parameters, namely turbine inlet temperature, recuperator inlet temperature and the low pressure compressor ratio. The maximum value of this ratio is found to be around 0.11. It is found that it is a strong function of the recirculation ratio and it decreased by 22% as the recirculation ratio is decreased by 70%. The thermodynamic impacts of water extraction on the system performance are also discussed. Based on these results, and prior results, which showed that the HPRTE is very compact, it appears that this cycle would be ideally suited for distributed power and vehicle applications, especially ones with associated air conditioning loads.

scholarly journals Design, Fabrication, and Testing of Ceramic Joints for High Temperature SiC/SiC Composites

2000 ◽  
Author(s):  
M. Singh ◽  
Edgar Lara-Curzio
Keyword(s):  
Silicon Carbide ◽  
Shear Strength ◽  
Elevated Temperatures ◽  
Stress Rupture ◽  
Ceramic Matrix Composites ◽  
Matrix Composites ◽  
Carbide Matrix ◽  
Sic Composites ◽  
Stress Rupture Testing

Various issues associated with the design and mechanical evaluation of joints of ceramic matrix composites are discussed. The specific case of an affordable, robust ceramic joining technology (ARCJoinT) to join silicon carbide (CG-Nicalon™) fiber-reinforced-chemically vapor infiltrated (CVI) silicon carbide matrix composites is addressed. Experimental results are presented for the time and temperature dependence of the shear strength of these joints in air up to 1200°C. From compression testing of double-notched joint specimens with a notch separation of 4 mm, it was found that the apparent shear strength of the joints decreased from 92 MPa at room temperature to 71 MPa at 1200°C. From shear stress-rupture testing in air at 1200°C it was found that the shear strength of the joints decreased rapidly with time from an initial shear strength of 71 MPa to 17.5 MPa after 14.3 hours. The implications of these results in relation to the expected long-term service life of these joints in applications at elevated temperatures are discussed.

Deposition of Volcanic Materials in the Hot Sections of Two Gas Turbine Engines

1993 ◽  
Vol 115 (3) ◽  
pp. 641-651 ◽  
Author(s):  
J. Kim ◽  
M. G. Dunn ◽  
A. J. Baran ◽  
D. P. Wade ◽  
E. L. Tremba
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Volcanic Ash ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
High Pressure Turbine ◽  
Deposition Behavior ◽  
Turbine Engine ◽  
Turbine Vanes ◽  
Volcanic Ash Cloud

This paper reports the results of a series of tests designed to determine the melting and subsequent deposition behavior of volcanic ash cloud materials in modern gas turbine engine combustors and high-pressure turbine vanes. The specific materials tested were Mt. St. Helens ash and a soil blend containing volcanic ash (black scoria) from Twin Mountain, NM. Hot section test systems were built using actual engine combustors, fuel nozzles, ignitors, and high-pressure turbine vanes from an Allison T56 engine can-type combustor and a more modern Pratt and Whitney F-100 engine annular-type combustor. A rather large turbine inlet temperature range can be achieved using these two combustors. The deposition behavior of volcanic materials as well as some of the parameters that govern whether or not these volcanic ash materials melt and are subsequently deposited are discussed.

Low NOx SEV Lean Premix Reheat Combustion in Alstom GT24 Gas Turbines

2015 ◽  
Author(s):  
Daniel Guyot ◽  
Gabrielle Tea ◽  
Christoph Appel
Keyword(s):  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Fuel Injection ◽  
Test Facility ◽  
Inlet Temperature ◽  
Combustion System ◽  
Operational Flexibility ◽  
Term Operation ◽  
Fuel Flexibility

Reducing gas turbine emissions and increasing their operational flexibility are key targets in today’s gas turbine market. In order to further reduce emissions and increase the operational flexibility of its GT24 (60Hz) and GT26 (50Hz), Alstom has introduced an improved SEV burner and fuel lance into its GT24 upgrade 2011 and GT26 upgrade 2011 sequential reheat combustion system. Sequential combustion is a key differentiator of Alstom GT24 engines in the F-class gas turbine market. The inlet temperature for the GT24 SEV combustor is around 1000 degC and reaction of the fuel/oxidant mixture is initiated through auto-ignition. The recent development of the Alstom sequential combustion system is a perfect example of evolutionary design optimizations and technology transfer between Alstom GT24 and GT26 engines. Better overall performance is achieved through improved SEV burner aerodynamics and fuel injection, while keeping the main features of the sequential burner technology. The improved SEV burner/lance concept has been optimized towards rapid fuel/oxidant mixing for low emissions, improved fuel flexibility with regards to highly reactive fuels (higher C2+ and hydrogen content), and to sustain a wide operation window. In addition, the burner front panel features an improved cooling concept based on near-wall cooling as well as integrated acoustics damping devices designed to reduce combustion pulsations thus extending the SEV combustor’s operation window even further. After having been validated extensively in the Alstom high pressure sector rig test facility, the improved GT24 SEV burner has been retrofitted into a commercial GT24 field engine for full engine validation during long-term operation. This paper presents the obtained high pressure sector rig and engine validation results for the GT24 (2011) SEV burner/lance hardware with a focus on reduced NOX and CO emissions and improved operational behavior of the SEV combustor. The high pressure tests demonstrated robust SEV burner/lance operation with up to 50% lower NOX formation and a more than 70K higher SEV burner inlet temperature compared to the GT24 (2006) hardware. For the GT24 engine with retrofitted upgrade 2011 SEV burner/lance all validation targets were achieved including an extremely robust operation behavior, up to 40% lower GT NOX emissions, significantly lower CO emissions at partload and baseload, a very broad operation window (up to 100K width in SEV combustor inlet temperature) and all measured SEV burner/lance temperatures in the expected range. Sector rig and engine validation results have confirmed the expected SEV burner fuel flexibility (up to 18%-vol. C2+ and up to 5%-vol. hydrogen as standard).

scholarly journals Development and Fabrication of Ceramic Gas Turbine Components

1996 ◽  
Author(s):  
Koichi Tanaka ◽  
Sazo Tsuruzono ◽  
Toshifumi Kubo ◽  
Makoto Yoshida
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Elevated Temperatures ◽  
Rupture Strength ◽  
High Stress ◽  
Stress Rupture ◽  
Inlet Temperature ◽  
Gas Generator ◽  
Rotating Speed ◽  
Ceramic Components

Kyocera has been developing various ceramic components for gas turbines under the Ceramic Gas Turbine (CGT) Project funded by the Japanese Government. This project has set a turbine inlet temperature (TIT) of 1350°C as a final target. For 1350°C TIT, we have developed a new silicon nitride material SN281, which has high stress rupture strength at elevated temperatures up to 1500°C. This material has excellent oxidation resistance as well. We have also developed improved sintering and inspection technologies for the use of SN281 as engine components. We are able to fabricate rotors and nozzles of the gas generator turbine (GGT) in good agreement with design geometry requirements, by optimizing sintering conditions. Small defects were also successfully detected by microfocus X-ray radiography. The SN281 rotors have attained 120% of design rotating speed at room temperature.

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