Assessing of Hot Gas Parts Using Advanced Eddy Current Testing Methods

2008 ◽  
Author(s):  
Matthias Jungbluth ◽  
Vinay Jonnalagadda ◽  
Erwan Baleine ◽  
Mattias Broddega˚rd ◽  
Rolf Wilkenho¨ner ◽  
...  
Keyword(s):  
Eddy Current ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Diagnostic Methods ◽  
Design Parameters ◽  
Gas Temperature ◽  
Diagnostic Measures ◽  
Hot Gas

The turbine section of state-of-the-art industrial gas turbines is exposed to the most severe conditions such as high temperatures, corrosive environments and high mechanical stresses for several tens of thousands of hours. To withstand these conditions, turbine blades and vanes have become the most sophisticated parts. This, together with advanced manufacturing technologies, strict quality requirements and maximum reliability demands, affects costs. Different design features have been realized in the past to meet the ambitious requirements, and are also under constant development. Blades and vanes made of superalloys with directionally-solidified or single-crystal structure are used to provide highest strengths at temperatures as near as possible to the hot gas temperature. The high integrity and conformity of the parts are required to realize the material potential. Different advanced diagnostic methods are applied to ensure these over time. Another way to increase the operating temperatures of gas turbines is the application of corrosion and thermal protection coatings for one or several rows of the blades and vanes. Deviations in the specified coating thickness tend to reduce the lifetime of such coatings significantly. Hence, the monitoring of this property during the manufacturing requires special nondestructive diagnostic measures. Service exposed parts, which need to be refurbished when the protective coatings are spent, offer a significant operation potential after refurbishment. To guarantee the design parameters during the next service interval, several nondestructive material evaluation methods are available for the necessary part property assessment. Multifrequency Eddy Current has proven itself as an appropriate NDE technique to accomplish the above diagnostic requirements. The paper will give an overview of results gained at Siemens with model based Eddy Current methods using measurement systems developed by Jentek Sensors Inc., USA, and CESI, Italy. Potential applications and limitations of the method also will be discussed.

Impact of Operating Conditions and Design Parameters on Gas Turbine Hot Section Creep Life

2010 ◽  
Author(s):  
S. Eshati ◽  
M. F. Abdul Ghafir ◽  
P. Laskaridis ◽  
Y. G. Li
Keyword(s):  
Gas Turbines ◽  
Performance Model ◽  
Operating Conditions ◽  
Creep Model ◽  
Design Parameters ◽  
Gas Temperature ◽  
Creep Life ◽  
Cooling Effectiveness ◽  
Radial Temperature ◽  
The Impact

This paper investigates the relationship between design parameters and creep life consumption of stationary gas turbines using a physics based life model. A representative thermodynamic performance model is used to simulate engine performance. The output from the performance model is used as an input to the physics based model. The model consists of blade sizing model which sizes the HPT blade using the constant nozzle method, mechanical stress model which performs the stress analysis, thermal model which performs thermal analysis by considering the radial distribution of gas temperature, and creep model which using the Larson-miller parameter to calculate the lowest blade creep life. The effect of different parameters including radial temperature distortion factor (RTDF), material properties, cooling effectiveness and turbine entry temperatures (TET) is investigated. The results show that different design parameter combined with a change in operating conditions can significantly affect the creep life of the HPT blade and the location along the span of the blade where the failure could occur. Using lower RTDF the lowest creep life is located at the lower section of the span, whereas at higher RTDF the lowest creep life is located at the upper side of the span. It also shows that at different cooling effectiveness and TET for both materials the lowest blade creep life is located between the mid and the tip of the span. The physics based model was found to be simple and useful tool to investigate the impact of the above parameters on creep life.

Repair of Advanced Gas Turbine Blades

2005 ◽  
Author(s):  
Julie McGraw ◽  
Reiner Anton ◽  
Christian Ba¨hr ◽  
Mary Chiozza
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
High Reliability ◽  
Turbine Blades ◽  
Base Material ◽  
Operating Experience ◽  
Cost Effective ◽  
Directionally Solidified ◽  
Hot Gas

In order to promote high efficiency combined with high power output, reliability, and availability, Siemens advanced gas turbines are equipped with state-of-the-art turbine blades and hot gas path parts. These parts embody the latest developments in base materials (single crystal and directionally solidified), as well as complex cooling arrangements (round and shaped holes) and coating systems. A modern gas turbine blade (or other hot gas path part) is a duplex component consisting of base material and coating system. Planned recoating and repair intervals are established as part of the blade design. Advanced repair technologies are essential to allow cost-effective refurbishing while maintaining high reliability. This paper gives an overview of the operating experience and key technologies used to repair these parts.

The Influence of Heat Transfer Effects on Turbine Performance Characteristics

2006 ◽  
Author(s):  
A. G. Stamatis ◽  
K. Mathioudakis
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Performance Characteristics ◽  
Gas Temperature ◽  
Hot Gas ◽  
Turbine Performance ◽  
Boundary Layer Development ◽  
Development Change ◽  
Cooling Air ◽  
Layer Development

A method allowing the evaluation of the effects related to heat transfer to the turbine blades on its performance characteristics is presented. The effects investigated are the change of passage dimensions, resulting from heat transfer and the change in flow field, exhibited mainly as a different boundary layer development. Change of hot gas temperature combined with cooling air temperature and possibly flow rate, result in a change of the temperature of the blade material, leading to dimension changes, because of the thermal expansion (dilatation). The changes in dimensions have a direct effect on turbine performance. An immediate consequence is a modification of the mass flow characteristic, due to a change of the throat area. Heat transfer also influences the properties of the gas flowing through the passage and in particular the characteristics of the boundary layers developing on the nozzle vanes and hub, tip endwals. Change of the thickness of this layer results in a change of blockage through the passage, a fact that influences directly the turbine flow function. The influence of both effects on turbine performance is studied. The study is performance oriented, aiming to the derivation of simplified models, which can be introduced in engine cycle decks.

scholarly journals Modeling of the shape of the deflector of the shell blade of marine gas turbine engines with varying parameters of thermal protection

2021 ◽  
pp. 111-116
Author(s):  
И.К. Андрианов ◽  
М.С. Гринкруг
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Thermal State ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Cooling Channels ◽  
Transfer Equations ◽  
Uniform Temperature Field

Работа посвящена исследованию проблемы управления тепловым состоянием оболочечных лопаток судовых турбин, находящихся в условиях высокотемпературного нагружения. В работе рассматривались вопросы сочетания внешней тепловой защиты с помощью теплоизоляционного покрытия и внутреннего охлаждения. Математическая модель теплопереноса строилась на основании дифференциальных уравнений теплопроводности Фурье, условия теплоотдачи в каналах охлаждения. Проведена оценка влияния состава покрытия не изменение формы оболочки дефлектора с целью интенсификации охлаждения при неизменных параметрах скорости и температуры хладагента на входе в канал. Решение системы нелинейных уравнений теплопереноса проведено с помощью метода конечных разностей. Проведен численный эксперимент при реализации равномерного температурного поля на поверхности тела лопатки. Предложенная математическая модель позволяет рассчитать геометрию дефлекторов охлаждаемых лопаток судовых газовых турбин. Применение модели и результатов расчетов позволит рационализировать процесс охлаждения лопаток турбин, выбирая оптимальные сочетания внешней тепловой защиты и расхода хладагента. The work is devoted to the study of the problem of controlling the thermal state of the shell blades of marine turbines under high-temperature loading conditions. The paper deals with the combination of external thermal protection with the help of thermal insulation coating and internal cooling. The mathematical model of heat transfer was built on the basis of the Fourier differential equations of thermal conductivity, the conditions of heat transfer in cooling channels. The influence of the coating composition on the change in the shape of the deflector shell was evaluated in order to intensify cooling at constant parameters of the speed and temperature of the refrigerant at the inlet to the channel. The solution of the system of nonlinear heat transfer equations is carried out using the finite difference method. A numerical experiment is performed for the realization of a uniform temperature field on the surface of the blade body. The proposed mathematical model allows us to calculate the geometry of the deflectors of the cooled blades of marine gas turbines. The application of the model and the results of the calculations will allow to rationalize the cooling process of the turbine blades, choosing the optimal combination of external thermal protection and refrigerant consumption.

scholarly journals Investigation of the Relationship between Degradation of the Coating of Gas Turbine Blades and Its Surface Color

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7843
Author(s):  
Mariusz Bogdan ◽  
Józef Błachnio ◽  
Artur Kułaszka ◽  
Dariusz Zasada
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Protective Coatings ◽  
Turbine Blades ◽  
Operating Time ◽  
Surface Color ◽  
Metallographic Examination ◽  
Gas Turbine Blades ◽  
Study Results ◽  
The Relationship

This article presents issues concerning the relationship between the degradation of the coating of gas turbine blades and changes in the color of its surface. Conclusions were preceded by the determination of parameters characterizing changes in the technical condition of protective coatings made based on a metallographic examination that defined the morphological modifications of the microstructure of the coating, chemical composition of oxides, and roughness parameters. It has been shown that an increased operating time causes parameters that characterize the condition of the blades to deteriorate significantly. Results of material tests were compared with those of blade surface color analyses performed using a videoscope. Image data were represented in two color models, i.e., RGB and L*a*b* with significant differences being observed between parameters in both representations. The study results demonstrated a relationship between the coating degradation degree and changes in the color of the blade’s surface. Among others, this approach may be used as a tool to assess the condition of turbine blades as well as entire gas turbines.

Effect of blowing ratio on Film-Cooling effectiveness of Ginkgo Shaped Holes: A numerical approach

2021 ◽  
Author(s):  
Muhammad Awais ◽  
Reaz Hasan ◽  
Md. Hamidur Rahman
Keyword(s):  
Film Cooling ◽  
Gas Turbines ◽  
Thermal Protection ◽  
Turbine Blades ◽  
Operating Conditions ◽  
Bottom Surface ◽  
Inlet Temperature ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Lift Off

Modern gas turbine engines operate at significantly high temperatures to improve thermal efficiency and power output to a greater extent. The enhancement in rotor inlet temperature (RIT) increases the heat transfer rate to the turbine blades which requires sophisticated cooling schemes to maintain the blade temperature in acceptable levels. Therefore, the present work refers to the numerical investigation of film cooling technique applied in gas turbines. The cooling performance of two different shaped holes namely Ginkgo Forward (GF) and Ginkgo Reverse (GR)) were investigated in terms of centerline and local lateral effectiveness and comprehensive comparison was made with the cooling performance of cylindrical (CY) hole. The investigations were performed at two density ratios (DR=1.6, 2.0) and three different blowing ratios (BR=1.0, 1.5 and 2.0). At all the operating conditions, the results demonstrated significant augmentation in centerline and lateral effectiveness when GR shaped hole was employed followed by the GF and CY cooling holes. For shaped holes, the low velocity gradient through the film alleviated jet lift off and turbulence intensity resulting in decreased entrainment of hot gas to bottom surface. To conclude, the lateral coverage due to the shaped cooling holes significantly enhanced the thermal protection and overall cooling performance.

Design and Analysis of a Real-Time Hot Gas Temperature Estimator for Heavy-Duty Gas Turbines

2015 ◽  
Author(s):  
Eric A. Müller ◽  
Adrian Ticǎ
Keyword(s):  
Real Time ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Gas Temperature ◽  
Heavy Duty ◽  
Component Level ◽  
Load Range ◽  
Hot Gas ◽  
Dynamic Tracking ◽  
Heavy Duty Gas Turbine

The knowledge about a relevant process and lifetime indicative quantity, such as the hot gas temperature, is crucial for the control of a gas turbine. Since this indicative process quantity usually cannot be directly measured, it has to be estimated. The paper describes a model-based method to accurately estimate in real-time the hot gas temperature of a heavy-duty gas turbine. The method follows a well-balanced trade-off between resulting prediction accuracy and involved computational complexity. It takes advantage of the capability of a component-level dynamic model to predict the system behaviour and of the capacity of a dynamic tracking filter to adapt to the current gas turbine conditions. In a simulation study, it is shown that the proposed design can provide an accurate hot gas temperature estimation over the entire gas turbine load range, along the gas turbine lifecycle, and during fast transient manoeuvres.

3-D Numerical Simulation of the Flow Through a Turbine Blade Cascade With Cooling Injection at the Leading Edge

1996 ◽  
Author(s):  
Dieter Bohn ◽  
Karsten Kusterer ◽  
Harald Schönenborn
Keyword(s):  
Numerical Simulation ◽  
Turbine Blade ◽  
Gas Turbines ◽  
Stokes Equations ◽  
Leading Edge ◽  
Body Region ◽  
Gas Temperature ◽  
Hot Gas ◽  
Blade Cascade ◽  
Flow Through

High process efficiencies and high power-weight ratios are two major requirements for the economic operation of present day gas turbines. This development leads to extremely high turbine inlet temperatures and adjusted pressure ratios. The permissible hot gas temperature is limited by the material temperature of the blade. Intensive cooling is required to guarantee an economically acceptable life of the components which are in contact with the hot gas. Although film-cooling has been successfully in use for a couple of years along the suction side and pressure side, problems occur in the vicinity of the stagnation point due to high stagnation pressures and opposed momentum fluxes. In this area basic investigations are necessary to achieve a reliable design of the cooled blade. In the present calculations, a code for the coupled simulation of fluid flow and heat transfer in solid bodies is employed. The numerical scheme works on the basis of an implicit finite volume method combined with a multi-block technique. The full, compressible 3-D Navier-Stokes equations are solved within the fluid region and the Fourier equation for beat conduction is solved within the solid body region. An elliptic grid generator is used for the generation of the structured computational grid, which is a combination of various C-type and H-type grids. Results of a 3-D numerical simulation of the flow through a turbine blade cascade with and without cooling ejection at the leading edge through two slots are presented. The results are compared with 2-D numerical simulations and experimental results. It is shown that the distribution of the coolant on the blade surface is influenced by secondary flow phenomena which can not be taken into account by the 2-D simulations. Further coupled simulations with non-adiabatic walls in the leading edge region are performed with realistic temperature ratios and compared to the same case with adiabatic walls. It is shown that in the case of non-adiabatic walls the temperature on the blade wall is significantly lower than in the case of adiabatic walls.

Finite Element Modeling of the Eddy-Current Inspection of Land-Based Gas Turbine Blades

2001 ◽  
Author(s):  
Hiroyuki Fukutomi ◽  
Takashi Ogata
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Gas Turbine ◽  
Eddy Current ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Multiple Cracks ◽  
Gas Turbine Blades ◽  
Element Modeling

There has been a growing need in recent technology of gas turbines in combined cycle to assess the remaining life of high temperature components. It is also required that the nondestructive assessment be more accurate in maintaining combined cycle plants. This paper describes the use of a simulator solving forward and inverse problems under eddy current testing, in parametric studies of inspection parameters for 1100°C-class gas turbine blades in terms of test probe capabilities, frequencies and signal interpretation. The simulator is based on a differential formulation constructed with a magnetic vector potential and a 3-dimensional edge-based finite-element modeling method. Its features are forming coils and defects independent of a whole finite element model, very fast eddy current response predictions, and identifications of electromagnetic properties. Using the simulator, optimal sensor types and test frequencies are determined in terms of assessment of degradation, selectability between surface-breaking and subsurface cracks, reconstruction of crack profiles, and detection of multiple cracks.

Initial Work on the Application of Protective Coatings to Marine Gas Turbine Components by High-Rate Sputtering

1974 ◽  
Author(s):  
E. D. McClanahan ◽  
R. Busch ◽  
J. W. Patten ◽  
J. Fairbanks
Keyword(s):  
Gas Turbines ◽  
Protective Coatings ◽  
Turbine Blades ◽  
High Rate ◽  
Sputtering Deposition ◽  
Fine Grained ◽  
Radio Frequency Sputtering ◽  
Initial Work ◽  
Fine Grained Structure ◽  
And Performance

Gas turbines operated in the marine environment are limited in life and performance by sulfidation or hot-corrosion. Protective coatings deposited by sputtering appear to have the potential of significantly increasing engine life over that obtained with current coatings produced by other techniques. The sputtering process and its application to coating hot section components is the subject of this paper. Two programs are described. In one, metallic overlay coatings of the CoCrAlY type were deposited by dc triode sputtering. Deposition conditions were determined which resulted in adherent, crack-free coatings with a fine grained structure. Platinum diffusion barrier layers were also investigated. Sputtering apparatus suitable for coating turbine blades and vanes was constructed. The other program utilized supported discharge radio frequency sputtering to deposit zirconia coatings, which were intended to serve a thermal barrier function as well as a corrosion resistant one. Graded composition interlayers were investigated as a means of improving the compatibility of the zirconia coating with superalloys.

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