A Viscoplastic Modeling Approach for MCrAlY Protective Coatings for Gas Turbine Applications

2008 ◽  
Author(s):  
Roland Mu¨cke
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Flow Characteristics ◽  
Strain Range ◽  
Substrate Material ◽  
Full Scale ◽  
Viscoplastic Material ◽  
Modeling Approach ◽  
Lifetime Analysis ◽  
Industrial Gas Turbines

MCrAlY coatings are applied in industrial gas turbines and aircraft engines to protect surfaces of hot gas exposed components from oxidation and corrosion at elevated temperature. Apart from oxidation resistance, coatings have to withstand cracking caused by cyclic deformation since coating cracks might propagate into the substrate material and thus limit the lifetime of the parts. In this context, the prediction of the coating maximum stress and strain range during cyclic loading is important for the lifetime analysis of coated components. Analyzing the state of stress in the coating requires the application of viscoplastic material models. A coupled full-scale cyclic analysis of substrate and coating, however, is very expensive because of the different flow characteristics of both materials. Therefore, this paper proposes an uncoupled modeling approach which consists of a full-scale cyclic analysis of the component without coating and a fast post-processing procedure based on a node-by-node integration of the coating constitutive model. This paper presents different aspects of the coating viscoplastic behavior and their computational modeling. The uncoupled analysis is explained in detail and a validation of the procedure is addressed. Finally, the application of the uncoupled modeling approach to a coated turbine blade exposed to a complex engine start-up and shut-down procedure is shown.

A Viscoplastic Modeling Approach for MCrAlY Protective Coatings for Gas Turbine Applications

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Roland Mücke
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Thermal Strain ◽  
Flow Characteristics ◽  
Strain Range ◽  
Substrate Material ◽  
Full Scale ◽  
Viscoplastic Material ◽  
Modeling Approach ◽  
Industrial Gas Turbines

MCrAlY coatings are applied in industrial gas turbines and aircraft engines to protect surfaces of hot gas exposed components from oxidation and corrosion at elevated temperature. Apart from oxidation resistance, coatings have to withstand cracking caused by cyclic deformation since coating cracks might propagate into the substrate material and thus limit the lifetime of the parts. In this context, the prediction of the coating maximum stress and the strain range during cyclic loading is important for the lifetime analysis of coated components. Analyzing the state of stress in the coating requires the application of viscoplastic material models. A coupled full-scale cyclic analysis of substrate and coating, however, is very expensive because of the different flow characteristics of both materials. Therefore, this paper proposes an uncoupled modeling approach, which consists of a full-scale cyclic analysis of the component without coating and a fast postprocessing procedure based on a node-by-node integration of the coating constitutive model. This paper presents different aspects of the coating viscoplastic behavior and their computational modeling. The uncoupled analysis is explained in detail and a validation of the procedure is addressed. Finally, the application of the uncoupled modeling approach to a coated turbine blade exposed to a complex engine start-up and shut-down procedure is shown. Throughout the paper bold symbols denote tensors and vectors, e.g., σ stands for the stress tensor with the components σij. The superscripts (.)S and (.)C symbolize the substrate and the coating, respectively, e.g., εthS stands for the tensor of substrate thermal strain. Further symbols are explained in the text.

Deformation and Fracture Behaviors in the Freestanding APS-TBC - Effects of Process Parameters and Thermal Exposure

2007 ◽  
Vol 353-358 ◽  
pp. 1935-1938 ◽  
Author(s):  
Yasuhiro Yamazaki ◽  
T. Kinebuchi ◽  
H. Fukanuma ◽  
N. Ohno ◽  
K. Kaise
Keyword(s):  
Mechanical Properties ◽  
Process Parameters ◽  
Gas Turbines ◽  
Thermal Exposure ◽  
Substrate Material ◽  
Process Variables ◽  
Microstructural Investigation ◽  
Deformation And Fracture ◽  
Industrial Gas Turbines ◽  
Tbc Systems

Thermal barrier coatings (TBCs), that reduce the temperature in the underlying substrate material, are an essential requirement for the hot section components of industrial gas turbines. Recently, in order to take full advantage of the potential of the TBC systems, experimental and analytical investigations in TBC systems have been performed. However there is a little information on the deformation behavior of the top coating. In addition, the effects of the thermal exposure and the process parameters on the mechanical properties of the top coating have never been clarified. From these backgrounds, the effects of the process variables in APS and the thermal exposure on the mechanical properties were investigated in order to optimize the APS process of top coatings. The experimental results indicated that the mechanical properties of the APS-TBC, i.e. the tensile strength and the elastic modulus, were significantly changed by the process variables and the long term thermal exposure. The microstructural investigation was also carried out and the relationship between the mechanical properties and the porosity was discussed.

Development of Low Emission Gas Turbine Combustors

2015 ◽  
Author(s):  
Seung-chai Jung ◽  
Siwon Yang ◽  
Shaun Kim ◽  
Ik Soo Kim ◽  
Chul-ju Ahn ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Flow Characteristics ◽  
Flame Stability ◽  
Fuel Distribution ◽  
Eddy Simulation ◽  
Piv Measurement ◽  
Planar Laser ◽  
Air Mixing ◽  
Industrial Gas Turbines ◽  
Combustion Tests

Due to increasing environmental concerns, clean technology has become a key feature in industrial gas turbines. Swirler design is directly associated with the combustion performance for its roles in fuel distribution and flame stability. In this study, the development process of three new conceptual swirlers from Samsung Techwin is presented. Each swirler has unique features to enhance fuel-to-air mixing; Swirler 1 uses tangential air-bypass, Swirler 2 minimizes pressure loss using impeller-like design, and Swirler 3 has combined flow characteristics of axial and radial swirlers. Using extensive computational fluid dynamics (CFD) analysis, lead time and cost in manufacturing the prototypes were significantly reduced. The numerical methods were verified with a lab-scale combustion test; particle image velocimetry (PIV) measurement of cold flow, direct flame images, and OH planar laser induced fluorescence (PLIF) images were compared with result of large-eddy simulation (LES), and they showed good agreement. After design optimization using CFD, full-scale combustion tests were performed for all three swirlers. Flame from each swirler was visualized using a cylindrical quartz liner; direct images and OH chemiluminescence images of flames were obtained. Flame stability and blow-off limit at various air load were examined by gradually lowering the equivalence ratio. NOx and CO concentration were measured at the exhaust. All three swirlers satisfied low NOx and CO levels at the design conditions. The performance maps bounded by the NOx and CO limits and blow-off limit were obtained for all swirlers. Further efforts to maximize the combustors performance will be made.

Dry, Low Emissions for the ‘H’ Heavy-Duty Industrial Gas Turbines: Full-Scale Combustion System Rig Test Results

2003 ◽  
Author(s):  
Geoff Myers ◽  
Dan Tegel ◽  
Markus Feigl ◽  
Fred Setzer ◽  
William Bechtel ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Combined Cycle ◽  
Full Scale ◽  
Combustion System ◽  
Heavy Duty ◽  
Test Program ◽  
Industrial Gas Turbines ◽  
Inlet Conditions

The lean, premixed DLN2.5H combustion system was designed to deliver low NOx emissions from 50% to 100% load in both the Frame 7H (60 Hz) and Frame 9H (50 Hz) heavy-duty industrial gas turbines. The H machines employ steam cooling in the gas turbine, a 23:1 pressure ratio, and are fired at 1440 C (2600 F) to deliver over-all thermal efficiency for the combined-cycle system near 60%. The DLN2.5H combustor is a modular can-type design, with 14 identical chambers used on the 9H machine, and 12 used on the smaller 7H. On a 9H combined-cycle power plant, both the gas turbine and steam turbine are fired using the 14-chamber DLN2.5H combustion system. An extensive full-scale, full-pressure rig test program developed the fuel-staged dry, low emissions combustion system over a period of more than five years. Rig testing required test stand inlet conditions of over 50 kg/s at 500 C and 28 bar, while firing at up to 1440 C, to simulate combustor operation at base load. The combustion test rig simulated gas path geometry from the discharge of the annular tri-passage diffuser through the can-type combustion liner and transition piece, to the inlet of the first stage turbine nozzle. The present paper describes the combustion system, and reports emissions performance and operability results over the gas turbine load and ambient temperature operating range, as measured during the rig test program.

scholarly journals Thermal Spray Manufacturing Issues in Coating IGT Hot Section Components

1997 ◽  
Author(s):  
P. Sahoo ◽  
T. Carr ◽  
R. Martin ◽  
F. Dinh
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Shop Floor ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Industrial Gas Turbines ◽  
And Performance ◽  
Thermally Sprayed ◽  
Practical Implications

The desire to improve the performance and efficiency of gas turbine engines has led to higher operating temperatures in the turbine sections of the engine. Present materials and materials under development for hot section turbine blades and vanes are not inherently resistant to hot corrosion, and therefore require protective coatings. In the past two decades this has led to increased use of thermally sprayed MCrAlY coatings, both as stand-alone overlay and as a bond coat for thermal barrier coatings. This paper reviews the issues involved in thermally sprayed MCrAlY and TB coatings onto hot section blades and vanes of industrial gas turbines. The generation of a specification for coating acceptance and its practical implications are discussed. The issues in applying such coatings will be discussed, along with references to manufacturing issues on the shop floor. The difficulties inherent in applying a line-of-sight coating to complex geometric shapes will be discussed, with particular reference to robotics spraying. The utility of using a design-of-experiment approach to satisfy the user will be reviewed. The testing, evaluation, and performance characteristics of typical coatings are discussed.

Factors for Improving Reliability in Large Industrial Gas Turbines

2004 ◽  
Author(s):  
K. Takahashi ◽  
K. Akagi ◽  
S. Nishimura ◽  
Y. Fukuizumi ◽  
V. Kallianpur
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Protective Coatings ◽  
Engine Design ◽  
Partial Load ◽  
Load Cycling ◽  
Aero Engine ◽  
Industrial Gas Turbines

The use of aero engine design methods and experience including higher temperature materials and protective coatings have significantly increased thermal efficiency, and output capability of large industrial gas turbines such as the F, G and H class. As a result the gas path components operate at much higher gas temperatures over significantly longer maintenance intervals, as compared to aero engine experience. Therefore, it is essential that the hardware durability can effectively endure longer periods of attack by oxidation, creep and fatigue because of longer operating intervals between scheduled maintenance periods. Another factor that has become increasingly important is the need for greater flexibility in power plant operation. Specifically, the power plants must operate reliably under more frequent cyclic operation, including partial load cycling. This is in addition to the normal dispatch cycle of the power plant (i.e. daily-start-stop, weekly-start-stop, etc). Gas Turbine reliability is directly dependent on hardware performance and durability. Therefore, the gas turbine must have sufficient design margin to sustain the synergistic effect of higher firing temperature, and the operational challenges associated with greater partial load cycling. This paper discusses Mitsubishi’s approach for achieving the above mentioned objectives so that the overarching goals of higher reliability and durability of hot components are achieved in large advanced gas turbines.

The Effect of Water Injection on Multi-Spool Gas Turbine Behaviour

2004 ◽  
Author(s):  
A. J. Meacock ◽  
A. J. White
Keyword(s):  
Gas Turbine ◽  
Power Output ◽  
Gas Turbines ◽  
Water Injection ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Water Droplets ◽  
Industrial Gas Turbines ◽  
Advanced Cycles ◽  
Gas Turbine Cycle

The injection of water droplets into industrial gas turbines is now common place and is central to several proposed advanced cycles. These cycles benefit from the subsequent reduction in compressor work, the increase in turbine work, and (in the case of recuperated cycles) reduction in compressor delivery temperature, which all act to increase the efficiency and power output. An investigation is presented here into the effect such water droplets will have on the operating point and flow characteristics of an aero-derivative gas turbine cycle. The paper first describes the development of a computer program to study the effects of water injection in multi-spool industrial gas turbines. The program can operate in two modes: the first uses pre-determined non-dimensional wet compressor maps to match the components and is instructive and fast but limited in scope; the second uses the compressor geometries as input and calculates the wet compressor operating conditions as and when required. As a result, it is more computationally demanding, but can cope with a wider range of circumstances. In both cases the compressor characteristics are calculated from a mean-line analysis using suitable loss, deviation and blockage models, coupled with Lagrangian-style droplet evaporation calculations. The program has been applied to a three-spool machine to address issues such as the effects of water-injection on power output and overall efficiency, and the off-design nature of the compressor operation.

Extended Fuel Flexibility Testing of Siemens Industrial Gas Turbines: A Novel Approach

2012 ◽  
Author(s):  
Mats Andersson ◽  
Anders Larsson ◽  
Annika Lindholm ◽  
Jenny Larfeldt
Keyword(s):  
Gas Turbines ◽  
Cost Effective ◽  
Full Scale ◽  
Engine Operation ◽  
Gaseous Fuels ◽  
Novel Approach ◽  
Fuel Flexibility ◽  
Industrial Gas Turbines ◽  
Combustion Monitoring ◽  
Testing Fuel

Opportunity gaseous fuels are of great interest for small and medium sized gas turbines. The variety of gaseous fuels that Siemens Industrial Turbomachinery AB (SIT) is requested to make judgments on is continuously expanding. From such requests follows an increasing need for testing new fuels. The SIT novel approach for fuel flexibility testing, EBIT, has been to combine the single burner rig testing with a full scale engine test to give a cost effective and flexible solution. The combination of the two approaches is accomplished by using a separate feed of testing fuel to one or more burners in a standard gas turbine installation where the other burners use standard fuel from standard fuel system for engine operation. The separate feed of testing fuel can be operated as a slave to engine governor heat demand, but can also be controlled independently. This paper describes how EBIT has been implemented and tested. Combustion monitoring techniques and measurements to check behavior and predictions for full scale engine tests are presented. Results from testing with a blended natural gas with more than 50% of heat input from pentane, C5H12, in a SGT-700 engine shows that the EBIT concept is possible and powerful. The SIT 3rd generation DLE burner proves to be very fuel flexible and tolerant to high levels of pentane in the fuel. Less than 20% increase in NOx emissions can be expected when using pentane rich fuels. The burner is used in the SGT-800 47MW engine and the SGT-700 31MW engine.

Fuel System Suitability Considerations for Industrial Gas Turbines

2004 ◽  
Vol 126 (1) ◽  
pp. 119-126 ◽  
Author(s):  
F. G. Elliott ◽  
R. Kurz ◽  
C. Etheridge ◽  
J. P. O’Connell
Keyword(s):  
Gas Turbines ◽  
Equations Of State ◽  
Dew Point ◽  
Liquid Fuels ◽  
Physical Parameters ◽  
Special Focus ◽  
Fuel System ◽  
Fuel Gas ◽  
Pressure Drops ◽  
Industrial Gas Turbines

Industrial Gas Turbines allow operation with a wide variety of gaseous and liquid fuels. To determine the suitability for operation with a gas fuel system, various physical parameters of the proposed fuel need to be determined: heating value, dew point, Joule-Thompson coefficient, Wobbe Index, and others. This paper describes an approach to provide a consistent treatment for determining the above physical properties. Special focus is given to the problem of determining the dew point of the potential fuel gas at various pressure levels. A dew point calculation using appropriate equations of state is described, and results are presented. In particular the treatment of heavier hydrocarbons, and water is addressed and recommendations about the necessary data input are made. Since any fuel gas system causes pressure drops in the fuel gas, the temperature reduction due to the Joule-Thompson effect has to be considered and quantified. Suggestions about how to approach fuel suitability questions during the project development and construction phase, as well as in operation are made.

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