Life Assessment of Gas Turbine Blades Under Creep Failure Mechanism Considering Humidity

2018 ◽  
Author(s):  
Bita Soltan Mohammad Lou ◽  
Mohammad Pourgol-Mohammad ◽  
Mojtaba Yazdani
Keyword(s):  
Gas Turbine ◽  
Failure Mechanism ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Prediction Models ◽  
Turbine Blades ◽  
Life Assessment ◽  
Creep Life ◽  
Creep Failure ◽  
Design Assessment

Gas turbines are the most important components in thermal power plants, and these components such as turbine has been studied carefully. Gas turbine components operate predominantly under elevated temperature and high stress, and consequently gradual deformation becomes temporally inevitable. In turbine blades, creep is common failure mechanism, and it is an important factor for design assessment. The gas turbine blade is a component operating at high elevated temperatures, requiring a cooling systems to reduce the temperature. Common power enhancement approach is to spray water into compressor, and it is how humidity becomes an important factor in creep failure mechanism. The humidity variability results in temperature level change during the turbine operation, potentially affecting the blades creep life. In this paper, first different creep life prediction models were classified, and then a new model is proposed for creep life considering humidity based on Arrhenius equation. In our study, failure criterion is rupture. As a case study, the creep life of Nimonic-90 alloy turbine blade was predicted using proposed method and compared with FEA results which collected by literature surveys. Proposed model is capable of predicting creep life with only knowing dry temperature (WAR = 0), and there is no need to measure blade temperature variation during operation. The influence of humidity (%WAR) were studied on turbine blades creep life, and results show that creep life of turbine blade increase with increasing humidity percentage.

The Influence of Humidity on the Creep Life of a High Pressure Gas Turbine Blade: Part II—Case Study

2012 ◽  
Author(s):  
S. Eshati ◽  
P. Laskaridis ◽  
A. Haslam ◽  
P. Pilidis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Life Assessment ◽  
Coolant Temperature ◽  
Creep Life

The determination of the rate of heat transfer from the turbine blade in a cross flow is important in hot section gas turbine life assessment. For design purposes, the rate of heat transfer is normally fixed by semi-empirical correlations. These correlations require knowledge of fluid properties which depend on temperature. For gases these properties are normally available only for the dry state, thus the possible effect of the water vapour content has been overlooked. Many gas turbines operate in environments in which air humidity is very low and therefore has little influence on gas turbine performance. However humidity becomes more important in hot, humid climates where there are large variations in ambient absolute humidity, especially in hot and humid climates. The aim of this paper is to investigate and present the effect of humidity at different operating conditions on the turbine blade coolant heat transfer and blade creep life. The effect of humidity was considered only on the air coolant side. he The heat transfer coefficient on the hot side was calculated for dry hot gas. This avoided the balancing effect of each other (heat transfer coefficient coolant side and hot side). The WAR at each operating point is quantified based on the ambient temperature and the relative humidity (0%–100%). Results showed that with increasing WAR the blade inlet coolant temperature reduced along the blade span. The blade metal temperature at each section was reduced as WAR increased, which in turn increased the blade creep life. The increase in WAR increased the specific heat of the coolant and increased the heat transfer capacity of the coolant air flow. Different operating points were also evaluated at different WAR and Tamb to identify the effect of WAR on the creep life. The results showed that an increase in WAR increased the blade creep life. The creep life of the blade at each section of interest was obtained as a function of the blade section stress and the blade metal section temperature using the LMP approach.

scholarly journals Sistema de información para la caracterización de imágenes de desgaste en álabes de rotor de una turbina de gas

2020 ◽  
pp. 27-34
Author(s):  
Luz Yazmín Villagrán-Villegas ◽  
Miguel Patiño-Ortiz ◽  
Luis Héctor Hernández-Gómez ◽  
Víctor Velázquez-Martínez
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Mechanical Failure ◽  
Total Loss ◽  
Mechanical Equipment ◽  
End User ◽  
Gas Turbine Blades ◽  
The Difference

In Mexico, the end user of gas turbines (PEMEX), in the NRF standard, requests the Goodman and Campbell diagrams for the acquisition of new turbo machinery. However, the requirement of the diagrams is not reported when the turbine is sent for overhaul. In this research article, it is suggested that the end user when carrying out a wear analysis of a turbine blade, know precisely the conditions of a blade in case of total loss of the machine or in conditions in which they send one or several turbine discs to the manufacturer and the conditions that receives after overhaul the discs. Wear and friction are the most adverse factors in reducing the useful life of mechanical equipment. The loss of a relatively small amount of material, in certain critical locations of any mechanical part, can make the difference between the damage and the good functioning of the gas turbine, so this research aims to characterize images of a turbine blade with in order to identify any wear or mechanical failure; analyzing the responses to deterministic and non-deterministic variables, looking for responses that contribute to the early detection of any mechanical failure that prevents the total loss of the gas turbine in operation. To achieve the objectives set out in this research, techniques and tools with a systemic and systematic approach are used, which will allow the characterization and interpretation of images of gas turbine blades.

Prediction and Analysis of Impact of TBC Oxidation on Gas Turbine Creep Life

2015 ◽  
Author(s):  
E. A. Ogiriki ◽  
Y. G. Li ◽  
Th. Nikolaidis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Prediction Models ◽  
Gas Turbine Engine ◽  
Operating Conditions ◽  
Creep Life ◽  
Premature Failure ◽  
Turbine Engine ◽  
Oxidation Rates ◽  
The Impact

Thermal Barrier Coatings (TBC) have been widely used in the power generation industry to protect turbine blades from damage in hostile operating environment. This allows either a high Turbine Entry temperature (TET) to be employed or a low percentage of cooling air to be used, both of which will improve the performance and efficiency of gas turbine engines. However, with continuous increases in turbine entry temperature aimed at improving the performance and efficiency of gas turbines, TBCs have become more susceptible to oxidation. Such oxidation has been largely responsible for the premature failure of most TBCs. Nevertheless, existing creep life prediction models that give adequate considerations to the effects of TBC oxidation on creep life are rare. The implication is that the creep life of gas turbines may be estimated more accurately if TBC oxidation is considered. In this paper, a performance-based integrated creep life model has been introduced with the capability of assessing the impact of TBC oxidation on the creep life and performance of gas turbines. The model comprises of a thermal, stress, oxidation, performance, and life estimation models. High Pressure Turbine (HPT) blades are selected as the life limiting component of the gas turbine. Therefore the integrated model was employed to investigate the effect of several operating conditions on the HPT blades of a model gas turbine engine using a Creep Factor approach. The results show that different operating conditions can significantly affect the oxidation rates of TBCs which in turn affect the creep life of HPT blades. For instance, TBC oxidation can speed up the overall life usage of a gas turbine engine from 4.22% to 6.35% within one year operation. It is the objective of this research that the developed method may assist gas turbine users in selecting the best mission profile that will minimize maintenance and operating costs while giving the best engine availability.

Evaluation of Electricity Cost in a Growing Market

2013 ◽  
Author(s):  
W. Mohamed ◽  
V. Sethi ◽  
P. Pilidis ◽  
A. O. Abu ◽  
A. Nasir ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Maintenance Cost ◽  
Creep Life ◽  
Cost Of Electricity ◽  
Electricity Cost ◽  
Power Setting ◽  
The Cost

Operating gas turbines at higher firing temperatures has been shown to be more thermally efficient with more power obtained from relatively less fuel. There is, however, an associated slight increase in operating and maintenance costs at higher power settings. This paper studies the relationship between gas turbine power setting, the hot gas-path components’ life consumption, operating and maintenance cost and how these parameters can affect the cost of electricity. A 165 MW gas turbine power plant is modelled and investigated with a comparative turbine blade lifing model that performs stress and thermal analysis, and creep life estimation using the parametric Larson Miller method. The outcomes of this analysis are then linked to an economic model to calculate the cost of generating electricity. The results shows that the optimum cost of electricity does not coincide with the lowest TET or power setting as would be expected when taking into account the creep life of the blade. This is because although lower TET results in improved component life, it will also result in lower thermal efficiency which is found to have a more significant impact on the overall electricity cost. In other words, the cost of electricity will increase at low TETs due to reduced thermal efficiency. On the other hand the cost of electricity will also increase at high TETs due to reduced turbine blade life that leads to increase in maintenance cost.

Novel Technology for Gas Turbine Blade Effusion Cooling

2006 ◽  
Author(s):  
Lorenzo Battisti ◽  
Roberto Fedrizzi ◽  
Giovanni Cerri
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Innovative Technology ◽  
Gas Turbine Blade ◽  
Combustion Chambers ◽  
Reliable Technique

Gas turbine combustion chambers and turbine blades require better cooling techniques to cope with the increase in operating temperatures with each new engine model. Current gas turbine inlet temperatures are approaching 2000 K. Such extreme temperatures, combined with a highly dynamic environment, result in major stress on components, especially combustion chamber and blades of the first turbine stages. A technique that has been extensively investigated is transpiration cooling, for both combustion chambers and turbine blades. Transpiration-cooled components have proved an effective way to achieve high temperatures and erosion resistance for gas turbines operating in aggressive environments, though there is a shortage of durable and proven technical solutions. Effusion cooling (full-coverage discrete hole film cooling), on the other hand, is a relatively simpler and more reliable technique offering a continuous coverage of cooling air over the component’s hot surfaces. This paper presents an innovative technology for the efficient effusion cooling of the combustor wall and turbine blades. The dedicated electroforming process used to manufacture effusive film cooling systems, called Poroform®, is illustrated. A numerical model is also presented, developed specifically for designing the distributions of the diameter and density of the holes on the cooled surface with a view to reducing the metal’s working temperature and achieving isothermal conditions for large blade areas. Numerical simulations were used to design the effusive cooling system for a first-stage gas turbine blade. The diameter, density and spacing of the holes, and the adiabatic film efficiency are discussed extensively to highlight the cooling capacity of the effusive system.

Life assessment of a high temperature probe designed for performance evaluation and health monitoring of an aero gas turbine engine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Benny George ◽  
Nagalingam Muthuveerappan
Keyword(s):  
Performance Evaluation ◽  
Gas Turbine ◽  
Health Monitoring ◽  
Gas Turbine Engine ◽  
Life Assessment ◽  
Exhaust Gas ◽  
Cycle Fatigue ◽  
Creep Life ◽  
Turbine Engine ◽  
Engine Components

AbstractTemperature probes of different designs were widely used in aero gas turbine engines for measurement of air and gas temperatures at various locations starting from inlet of fan to exhaust gas from the nozzle. Exhaust Gas Temperature (EGT) downstream of low pressure turbine is one of the key parameters in performance evaluation and digital engine control. The paper presents a holistic approach towards life assessment of a high temperature probe housing thermocouple sensors designed to measure EGT in an aero gas turbine engine. Stress and vibration analysis were carried out from mechanical integrity point of view and the same was evaluated in rig and on the engine. Application of 500 g load concept to clear the probe design was evolved. The design showed strength margin of more than 20% in terms of stress and vibratory loads. Coffin Manson criteria, Larsen Miller Parameter (LMP) were used to assess the Low Cycle Fatigue (LCF) and creep life while Goodman criteria was used to assess High Cycle Fatigue (HCF) margin. LCF and HCF are fatigue related damage from high frequency vibrations of engine components and from ground-air-ground engine cycles (zero-max-zero) respectively and both are of critical importance for ensuring structural integrity of engine components. The life estimation showed LCF life of more than 4000 mission reference cycles, infinite HCF life and well above 2000 h of creep life. This work had become an integral part of the health monitoring, performance evaluation as well as control system of the aero gas turbine engine.

Life assessment of a high temperature probe designed for performance evaluation and health monitoring of an aero gas turbine engine

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Benny George ◽  
Nagalingam Muthuveerappan
Keyword(s):  
Performance Evaluation ◽  
Gas Turbine ◽  
Health Monitoring ◽  
Gas Turbine Engine ◽  
Life Assessment ◽  
Exhaust Gas ◽  
Cycle Fatigue ◽  
Creep Life ◽  
Turbine Engine ◽  
Engine Components

Abstract Temperature probes of different designs were widely used in aero gas turbine engines for measurement of air and gas temperatures at various locations starting from inlet of fan to exhaust gas from the nozzle. Exhaust Gas Temperature (EGT) downstream of low pressure turbine is one of the key parameters in performance evaluation and digital engine control. The paper presents a holistic approach towards life assessment of a high temperature probe housing thermocouple sensors designed to measure EGT in an aero gas turbine engine. Stress and vibration analysis were carried out from mechanical integrity point of view and the same was evaluated in rig and on the engine. Application of 500 g load concept to clear the probe design was evolved. The design showed strength margin of more than 20% in terms of stress and vibratory loads. Coffin Manson criteria, Larsen Miller Parameter (LMP) were used to assess the Low Cycle Fatigue (LCF) and creep life while Goodman criteria was used to assess High Cycle Fatigue (HCF) margin. LCF and HCF are fatigue related damage from high frequency vibrations of engine components and from ground-air-ground engine cycles (zero-max-zero) respectively and both are of critical importance for ensuring structural integrity of engine components. The life estimation showed LCF life of more than 4000 mission reference cycles, infinite HCF life and well above 2000 h of creep life. This work had become an integral part of the health monitoring, performance evaluation as well as control system of the aero gas turbine engine.

Recent Advances in the Study of Film Cooling on the Gas Turbine Blade

2014 ◽  
Vol 971-973 ◽  
pp. 143-147 ◽  
Author(s):  
Ping Dai ◽  
Shuang Xiu Li
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Gas Turbines ◽  
High Performance ◽  
Leading Edge ◽  
Development Trend ◽  
Research Progress ◽  
Gas Turbine Blade ◽  
New Generation

The development of a new generation of high performance gas turbine engines requires gas turbines to be operated at very high inlet temperatures, which are much higher than the allowable metal temperatures. Consequently, this necessitates the need for advanced cooling techniques. Among the numerous cooling technologies, the film cooling technology has superior advantages and relatively favorable application prospect. The recent research progress of film cooling techniques for gas turbine blade is reviewed and basic principle of film cooling is also illustrated. Progress on rotor blade and stationary blade of film cooling are introduced. Film cooling development of leading-edge was also generalized. Effect of various factor on cooling effectiveness and effect of the shape of the injection holes on plate film cooling are discussed. In addition, with respect to progress of discharge coefficient is presented. In the last, the future development trend and future investigation direction of film cooling are prospected.

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.

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