scholarly journals Service Temperature Estimation for Gas Turbine Buckets Based on Microstructure Change.

1996 ◽  
Vol 45 (6) ◽  
pp. 699-704 ◽  
Author(s):  
Yomei YOSHIOKA ◽  
Nagatoshi OKABE ◽  
Daizo SAITO ◽  
Kazunari FUJIYAMA ◽  
Takanari OKAMURA
Keyword(s):  
Gas Turbine ◽  
Service Temperature ◽  
Temperature Estimation ◽  
Microstructure Change

Service Temperature Estimation of Turbine Blades Based on Microstructural Observations

1990 ◽  
Author(s):  
Jose M. Aurrecoechea ◽  
William D. Brentnall ◽  
Joseph R. Gast
Keyword(s):  
Mathematical Model ◽  
Turbine Blades ◽  
Turbine Engines ◽  
Computational Technique ◽  
Gas Turbine Engines ◽  
Service Temperature ◽  
Temperature Estimation ◽  
Gamma Prime ◽  
Diffusion Controlled ◽  
Nickel Base

Optical and electron metallographic (SEM) examination was performed on MAR-M-421 samples subjected to controlled furnace exposures, to quantify the microstructural changes associated with the prolonged high temperature exposures. Gamma prime size measurements were used to generate a mathematical model, based on diffusion controlled kinetics, designed to estimate temperatures. This computational technique was utilized to estimate exposure temperatures of turbine blades which had seen service in land based gas turbine engines. The engines had accumulated from 1,200 to more than 98,000 hours, operating under a variety of conditions. The procedure is generally applicable to commonly used gamma prime strengthened nickel-base superalloys.

Development of Temperature Estimation Method for a Gas Turbine Transition Piece

2016 ◽  
Author(s):  
Mitsutoshi Okada ◽  
Toshihiko Takahashi ◽  
Susumu Yamada ◽  
Takayuki Ozeki ◽  
Tomoharu Fujii
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Gas Turbine ◽  
Estimation Method ◽  
Life Assessment ◽  
Estimation Methods ◽  
Test Time ◽  
Internal Cooling ◽  
Temperature Estimation ◽  
Transition Piece

Temperature estimation methods for a transition piece of a gas turbine are developed in terms of microstructural changes and computational fluid dynamics (CFD) for life assessment. Temperature is estimated to be low around the center of the component where thermal barrier coating (TBC) is deposited on the Ni-base superalloy and a combination of internal cooling and film cooling is also applied. Test specimens are prepared from the above area for a high-temperature heating test in air. The microstructure in the superalloy and TBC is investigated after the test. The thermally grown oxide (TGO) formed on the bondcoat surface increases with the square root of the test time, and on the basis of this relation, a temperature-estimation equation is obtained. The estimated temperature distribution is compared with a numerical heat transfer simulation by means of CFD. The geometry of the transition piece with internal cooling structure is acquired using an X-ray computerized radiography and a laser digitizer, and it is modeled for the numerical simulation. The heat conduction analysis is applied to the transition piece, and the convection and radiation heat transfer analyses are applied to the gas path and internal cooling flow. These analyses are conjugated to estimate the temperature distribution. The simulation result agrees well with the estimation using TGO thickness.

Measurement Error Influence on Gas Turbine Operability for Condition-Based Maintenance and Reliability/Availability Improvement

2008 ◽  
Author(s):  
Ever Avriel Fadlun ◽  
Ilaria Michelizzi ◽  
Marco De Iaco
Keyword(s):  
Gas Turbine ◽  
Firing Temperature ◽  
Pressure Measurement ◽  
Condition Based Maintenance ◽  
Life Assessment ◽  
Temperature Estimation ◽  
Machine Operation ◽  
Discharge Pressure ◽  
And Control ◽  
Accuracy And Stability

Nowadays the major oil & gas companies are forced to move to a condition-based maintenance in order to extend mean time between maintenance (MTBM) and increase productivity, predicting gas turbine behavior and preventing unexpected failures. Gas turbine operability is influenced by many technological limitations, such as high temperature exposure limit of hot components, requested fuel composition flexibility, combustion chamber pulsations, pollutant emissions, rotor vibrations, compressor surge limit etc. In order to prevent exceeding these limitations certain significant measurable variables are monitored and controlled during machine operation; the instrumentation accuracy and stability have a strong impact on gas turbine reliability, availability and control. The aim of this paper is to demonstrate how the accuracy and stability of the instrumentation installed on a gas turbine has a direct influence on its operability. Monte Carlo simulations have been carried out to assess each instrument deviation effect and the level of impact. The second phase is oriented towards establishing an improvement process for a safe and reliable machine operation. Among the above-mentioned critical limits the main focus of this analysis is the firing temperature estimation and its control, which is performed by measuring gas turbine exhaust temperature and compressor discharge pressure. This study has highlighted how an error on compressor discharge pressure measurement during unit operation may provoke gas turbine over-firing or under-firing, respectively causing fast life reduction of hot components and the limitation of maximum delivered power. Furthermore, an error on compressor discharge pressure measurement would strongly decrease firing temperature estimation confidence, which is the main parameter for components residual life assessment to target a condition-based maintenance approach. In this paper the corrective actions to increase the accuracy of firing temperature estimation and control will be described. Based on the results of this study, reliability and availability improvements will also be presented. Using the present work as a guideline, similar analyses can be carried out for all other critical aspects that can be related to measurable variables.

scholarly journals Phase evolution in an MCrAlY coating during high temperature exposure

2012 ◽  
Vol 48 (3) ◽  
pp. 359-365 ◽  
Author(s):  
C. Costa ◽  
E. Barbareschi ◽  
P. Guarnone ◽  
G. Borzone
Keyword(s):  
Gas Turbine ◽  
Turbine Blades ◽  
Phase Evolution ◽  
Residual Lifetime ◽  
Service Temperature ◽  
Electron Backscattered Diffraction ◽  
Gas Turbine Blades ◽  
Mcraly Coating ◽  
Direct Measurements ◽  
Temperature Exposure

MCrAlY (M = Ni and/or Co) coating systems are often applied on gas turbine blades and vanes to withstand the challenges of severe conditions. During service MCrAlY coatings are subjected to microstructural transformations that can be an indication of components service temperatures. The development of indirect methods to measure this parameter is of great concern in the gas turbine ?world? due to the impossibility of direct measurements. In the present work the evolution of an MCrAlY coating applied on Rene80 by LPPS (Low Pressure Plasma Spray) technique has been studied in order to verify if it was possible to identify a microstructural indicator of the service temperature. The specimens were exposed for different lengths of time at test temperatures of 700 - 800 - in order to characterize the phase evolution with time and temperature. Selective etching was employed for optical metallographic investigation. Scanning Electron Microscopy (SEM) observation combined with Electron Backscattered Diffraction (EBSD) and Energy Dispersive Spectroscopy (EDS) showed that the coating is composed of a ?- Co matrix, ?-AlNi, ?-(Cr, Co), Cr carbide and Y-rich phases. Among these phases, the sigma phase resulted in a temperature - composition dependence that can be a useful tool for evaluating the local service temperature and modelling the residual lifetime.

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