A New Analytical Model for Interpreting the Wear Mechanisms of Abradable Seal Systems and Verification by Testing

1989 ◽  
Author(s):  
J. Soehngen
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Analytical Model ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Ceramic Materials ◽  
Analytical Prediction ◽  
Material Loss ◽  
Blade Tip ◽  
Engine Components

In order to minimize the specific fuel consumption of gas turbines it is necessary to increase the gas temperatures and pressure ratios. Therefore, new high-temperature resistant abradable seal systems must be developed, especially for the hot section. Since the required operating temperatures are above 1050°C, the use of metallic materials as abradables is out of the question. A problem commonly encountered in the selection of new (ceramic) materials for seal systems is that of insufficient knowledge of the tribological process occurring when turbine blades rub against an abradable seal. The purpose of the investigation was to find a simplified analytical model to describe the tribological process occurring in the rubbing of the blades against the seal, in order to help in the preselection of materials for abradable seals. The model was verified by testing high-temperature resistant abradable seals under simulated engine conditions, followed by metallurgical examination. The results of the examination of two abradable seals on run engine components confirmed the analytical prediction and laboratory tests. The differences in material loss from the blade and the abradable seal can be correlated to the heat flux distribution in the sliding parts. Using different materials on the blade tip and stationary seal (e.g. ceramic blade tip and ceramic or metallic abradable seal), the heat flux can be directed in such a way that the wear takes place largely on the static part of the engine. By calculating their relative abradability, material combinations with optimum performance for each seal application can be found.

Development and Fabrication of Silicon Nitride Components for Ceramic Gas Turbine

1997 ◽  
Author(s):  
Keisuke Makino ◽  
Ken-Ichi Mizuno ◽  
Toru Shimamori
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
High Strength ◽  
Inlet Temperature ◽  
Turbine Inlet Temperature ◽  
Spark Plug ◽  
Power Turbine

NGK Spark Plug Co., Ltd. has been developing various silicon nitride materials, and the technology for fabricating components for ceramic gas turbines (CGT) using theses materials. We are supplying silicon nitride material components for the project to develop 300 kW class CGT for co-generation in Japan. EC-152 was developed for components that require high strength at high temperature, such as turbine blades and turbine nozzles. In order to adapt the increasing of the turbine inlet temperature (TIT) up to 1,350 °C in accordance with the project goals, we developed two silicon nitride materials with further unproved properties: ST-1 and ST-2. ST-1 has a higher strength than EC-152 and is suitable for first stage turbine blades and power turbine blades. ST-2 has higher oxidation resistance than EC-152 and is suitable for power turbine nozzles. In this paper, we report on the properties of these materials, and present the results of evaluations of these materials when they are actually used for CGT components such as first stage turbine blades and power turbine nozzles.

scholarly journals Analytical and Experimental Study of Residual Stresses in Thermal Barrier Coatings Deposited on Gas Turbine Blades in Laboratory Dimensions by APS and HVOF Methods to Calculate the Optimal Thickness

2021 ◽  
Vol 3 (1) ◽  
pp. 63-67
Author(s):  
Esmaeil Poursaeidi ◽  
◽  
Farzam Montakhabi ◽  
Javad Rahimi ◽  
◽  
...  
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Analytical Model ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Inlet Temperature ◽  
Optimal Thickness ◽  
Barrier Coatings

The constant need to use gas turbines has led to the need to increase turbines' inlet temperature. When the temperature reaches a level higher than the material's tolerance, phenomena such as creep, changes in mechanical properties, oxidation, and corrosion occur at high speeds, which affects the life of the metal material. Nowadays, operation at high temperatures is made possible by proceedings such as cooling and thermal insulation by thermal barrier coatings (TBCs). The method of applying thermal barrier coatings on the turbine blade creates residual stresses. In this study, residual stresses in thermal barrier coatings applied by APS and HVOF methods are compared by Tsui–Clyne analytical model and XRD test. The analytical model results are in good agreement with the experimental results (between 2 and 8% error), and the HVOF spray method creates less residual stress than APS. In the end, an optimal thickness for the coating is calculated to minimize residual stress at the interface between the bond coat and top coat layers.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2001 ◽  
Author(s):  
Nagaraj K. Arakere
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
High Temperature ◽  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Turbine Blades ◽  
The Core ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4 and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the Space Shuttle Main Engine (SSME) fuel turbopump are discussed. During testing many turbine blades experienced Stage II non-crystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β = 45+/- 15 degrees tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined Low Cycle Fatigue (LCF) properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75 F – 1800 F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for LCF data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the LCF data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature LCF data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with LCF test data. These curve fits can be used for assessing blade fatigue life.

Development and Testing of Harsh Environment, Wireless Sensor Systems for Industrial Gas Turbines

2009 ◽  
Author(s):  
David Mitchell ◽  
Anand Kulkarni ◽  
Alex Lostetter ◽  
Marcelo Schupbach ◽  
John Fraley ◽  
...  
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Condition Based Maintenance ◽  
Harsh Environment ◽  
Sensor Systems ◽  
Wireless Telemetry ◽  
Industrial Gas Turbines

The potential for savings provided to worldwide operators of industrial gas turbines, by transitioning from the current standard of interval-based maintenance to condition-based maintenance may be in the hundreds of millions of dollars. In addition, the operational flexibility that may be obtained by knowing the historical and current condition of life-limiting components will enable more efficient use of industrial gas turbine resources, with less risk of unplanned outages as a result of off-parameter operations. To date, it has been impossible to apply true condition-based maintenance to industrial gas turbines because the extremely harsh operating conditions in the heart of a gas turbine preclude using the necessary advanced sensor systems to monitor the machine’s condition continuously. Siemens, Rove Technical Services, and Arkansas Power Electronics International are working together to develop a potentially industry-changing technology to build smart, self-aware engine components that incorporate embedded, harsh-environment-capable sensors and high temperature capable wireless telemetry systems for continuously monitoring component condition in the hot gas path turbine sections. The approach involves embedding sensors on complex shapes, such as turbine blades, embedding wireless telemetry systems in regions with temperatures that preclude the use of conventional silicon-based electronics, and successfully transmitting the sensor information from an environment very hostile to wireless signals. The results presented will include those from advanced, harsh environment sensor and wireless telemetry component development activities. In addition, results from laboratory and high temperature rig and spin testing will be discussed.

Stability of TaC precipitates in a Co–Re-based alloy being developed for ultra-high-temperature applications

2016 ◽  
Vol 49 (4) ◽  
pp. 1253-1265 ◽  
Author(s):  
Ralph Gilles ◽  
Debashis Mukherji ◽  
Lukas Karge ◽  
Pavel Strunz ◽  
Premysl Beran ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Gas Turbines ◽  
Volume Fraction ◽  
Turbine Blades ◽  
Alloy Development ◽  
Carbide Phases ◽  
Ultra High Temperature ◽  
Temperature Applications

Co–Re alloys are being developed for ultra-high-temperature applications to supplement Ni-based superalloys in future gas turbines. The main goal of the alloy development is to increase the maximum service temperature of the alloy beyond 1473 K,i.e.at least 100 K more than the present single-crystal Ni-based superalloy turbine blades. Co–Re alloys are strengthened by carbide phases, particularly the monocarbide of Ta. The binary TaC phase is stable at very high temperatures, much greater than the melting temperature of superalloys and Co–Re alloys. However, its stability within the Co–Re–Cr system has never been studied systematically. In this study an alloy with the composition Co–17Re–23Cr–1.2Ta–2.6C was investigated using complementary methods of small-angle neutron scattering (SANS), scanning electron microscopy, X-ray diffraction and neutron diffraction. Samples heat treated externally and samples heatedin situduring diffraction experiments exhibited stable TaC precipitates at temperatures up to 1573 K. The size and volume fraction of fine TaC precipitates (up to 100 nm) were characterized at high temperatures within situSANS measurements. Moreover, SANS was used to monitor precipitate formation during cooling from high temperatures. When the alloy is heated the matrix undergoes an allotropic phase transformation from the ∊ phase (hexagonal close-packed) to the γ phase (face-centred cubic), and the influence on the strengthening TaC precipitates was also studied within situSANS. The results show that the TaC phase is stable and at these high temperatures the precipitates coarsen but still remain. This makes the TaC precipitates attractive and the Co–Re alloys a promising candidate for high-temperature application.

Fundamental Coating Development Study to Improve the Isothermal Oxidation Resistance and Thermal Cycle Durability of Thermal Barrier Coatings

2006 ◽  
Vol 522-523 ◽  
pp. 247-254 ◽  
Author(s):  
Taiji Torigoe ◽  
Hidetaka Oguma ◽  
Ikuo Okada ◽  
Guo Chun Xu ◽  
Kazuhisa Fujita ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Barrier Coatings ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Atmospheric Plasma ◽  
Zirconia Ceramic ◽  
Thermal Barrier ◽  
Temperature Oxidation ◽  
Barrier Coatings ◽  
Oxidation Properties

Thermal barrier coatings(TBCs) are used in high temperature gas turbines to reduce the surface temperature of cooled metal parts such as turbine blades[1]. TBC consist of a bondcoat (e.g. MCrAlY where M is Co, Ni, CoNi, etc.) and a partially stabilized zirconia ceramic topcoat. Usually, the MCrAlY bondcoat is applied by LPPS (low pressure plasma spray) or HVOF(high velocity oxi-fuel spray). The topcoat is applied by APS (atmospheric plasma splay) or EB-PVD (electron beam-physical vapor deposition). High temperature oxidation properties, thermal barrier properties and durability of TBC are very important to increase the reliability in high temperature service. In this study, new TBC has been investigated. The new TBC consists of a two-layered bondcoat (LPPS-MCrAlY plus dense PVD overlay MCrAlY) and the EB-PVD type YSZ columnar structure topcoat. As a result of evaluation tests, it was confirmed that the new TBC had better oxidation properties and durability than a conventional TBC system.

scholarly journals Current Status of Ceramic Gas Turbine R&D in Japan

1989 ◽  
Author(s):  
Kiichiro Yamagishi ◽  
Yukio Yamada ◽  
Yoshihiro Echizenya ◽  
Shoji Ishiwata
Keyword(s):  
Gas Turbines ◽  
Technology Development ◽  
Ceramic Materials ◽  
Current Status ◽  
Inlet Temperature ◽  
Development Organization ◽  
New Energy ◽  
Ceramic Components ◽  
Preliminary Study ◽  
Engine Components

The Japanese Ministry of International Trade and Industry (MITI) has started two nine-year national R&D projects for small-capacity ceramic gas turbines (CGTs) from 1988, following several preliminary investigations of the technical aspects and of the social impacts of CGTs. Planned 300kW industrial ceramic gas turbines are to be used for co-generation and mobile power generation. The goals are 42% and higher for the thermal efficiency at the turbine inlet temperature of 1350°C, and the emission from the exhaust gas should meet the regulatory values. Also ceramic components have the goals of 400MPa for the minimum flexure strength at 1500°C, and 15 MPam1/2 for the fracture toughness. New Energy and Industrial Technology Development Organization (NEDO) is the main contractor, and three groups of private industries are the subcontractors for 300kW industrial CGT project. Three national research institutes are involved in the projects to conduct supportive research of ceramic materials and engine components as well as to carry out assessment of the materials and engine systems developed by the private industries. The development of 100kW CGT for automotive use was also recommended in the above stated investigations and a two-year preliminary study started in 1988. The full-scale 100kW automotive CGT R&D project is scheduled to start in 1990 after the preliminary study. Japan Automobile Research Institute, Inc. (JARI) is the main contractor for 100kW automotive CGT project with the cooperation of three automobile companies.

Model Combustor to Assess the Oxidation Behavior of Ceramic Materials Under Real Engine Conditions

1999 ◽  
Author(s):  
D. Filsinger ◽  
A. Schulz ◽  
S. Wittig ◽  
C. Taut ◽  
H. Klemm ◽  
...  
Keyword(s):  
High Temperature ◽  
International Development ◽  
Gas Turbines ◽  
Gas Flow ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
Ceramic Materials ◽  
Test Rig ◽  
Combustion Gas ◽  
Wide Range

A further increase of thermal efficiency and a reduction of the exhaust emissions of ground based gas turbines can be achieved by introducing new high temperature resistant materials. Therfore, ceramics are under international development. They offer excellent strengths at room and elevated temperatures. For gas turbine combustor applications, however, these materials have to maintain their advantageous properties under hostile environment. For the assessment and comparison of the oxidation behavior of different nonoxide ceramic materials a test rig was developed at the Institute for Thermal Turbomachinery (ITS), University of Karlsruhe, Germany. The test rig was integrated into the high temperature/ high pressure laboratory. A ceramic model combustion chamber was designed which allowed the exposure of standard four-point flexure specimens to the hot combustion gas flow. Gas temperatures and pressures could be varied in a wide range. Additionally, the partial steam pressure could be adjusted to real combustor conditions. The present paper gives a detailed description of the test rig and presents results of 100 hours endurance tests of ceramic materials at 1400°C. The initial strengths and the strengths after oxidation tests are compared. In addition to this, photographs illustrating the changes of the material’s microstructure are presented.

Turbine Tip Clearance Measurement System Evaluation on an Industrial Gas Turbine

1997 ◽  
Author(s):  
S. J. Gill ◽  
M. D. Ingallinera ◽  
A. G. Sheard
Keyword(s):  
Gas Turbine ◽  
Measurement System ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Tip Clearance ◽  
Real Time Measurement ◽  
Gap Measurement ◽  
Industrial Gas Turbines ◽  
Blade Tip ◽  
Industrial Gas Turbine

The continuing development of industrial gas turbines is resulting in machines of increasing power and efficiency. The need to continue this trend is focusing attention on minimizing all loss mechanisms within the machine, including those associated with turbine blade tip clearance. In order to study tip clearance in the turbine, real time measurement is required of clearance between turbine blades and the casing in which they run. This measurement is not routinely performed, due to the harsh nature of the turbine environment. On those occasions when turbine tip clearance is measured, it is typically in development vehicles, often using cooled probes that are somewhat unsuitable for use in production gas turbines. In this paper a program of work is reported that was undertaken with the purpose of identifying a promising turbine tip clearance measurement system that used the capacitive gap measurement technique. Issues surrounding the application of three systems to the turbine section of a GE MS6001FA gas turbine are identified and reported. Performance of the three evaluated systems is analyzed.

Wear Mechanisms of Mcraiy Abradable Plasma-Sprayed Coatings

1998 ◽  
Author(s):  
S. Li ◽  
C. Langlade-Bomba ◽  
D. Treheux ◽  
F. Crabos ◽  
P. Monge-Cadet
Keyword(s):  
Wear Mechanisms ◽  
Gas Turbines ◽  
Coating Microstructure ◽  
Blade Tip ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Abradable Coatings ◽  
Engine Components ◽  
New Generation ◽  
Sprayed Coatings

Abstract Reduction of operating clearance between the HP turbine and the shroud in the new generation of gas turbines is one way often used by engine manufacturers to improve efficiency. This implies developing a blade tip coating/shroud coating system to minimize the degradation (particularly blades wear) during eventual rubbing. In this study, the chosen systems are: - VPS NiCoCrAIYTa as HP blade tip coating, - Plasma-sprayed MCrAIY coatings deposited under various atmosphere as abradable coatings. In order to understand the wear mechanisms of these systems tribological tests (block on ring and fretting) were performed to study the influence of the coating microstructure on the wear mechanisms. The results were compared and correlated to those of rub tests performed with real engine components.

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