The Analysis of Heat Transfer and Thermal Stresses in Thermal Barrier Coatings under Exploitation

2012 ◽  
Vol 326-328 ◽  
pp. 530-535 ◽  
Author(s):  
Tomasz Sadowski ◽  
Przemysław Golewski
Keyword(s):  
Thermal Stresses ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Internal Cooling ◽  
Ansys Fluent ◽  
Combustion Gases ◽  
Barrier Coating ◽  
Working Medium ◽  
Aero Engines ◽  
Abaqus Code

Effectiveness of internal combustion turbines in aero-engines is limited by comparatively low temperature of exhaust gas at the entry to turbine of the engine. A thermal efficiency and other capacities of turbine strongly depend on the ratio of the highest to the lowest temperature of a working medium. Continuous endeavour to increase the thermal resistance of engine elements requires, apart from laboratory investigations, also numerical studies in 3D of different aero-engine parts. In the present work, the effectiveness of the protection of turbine blades by thermal barrier coating and internal cooling under thermal shock cooling was analysed numerically using the ABAQUS code. The phenomenon of heating the blade from temperature of combustion gases was studied. This investigation was preceded by the CFD analysis in the ANSYS Fluent program which allows for calculation of the temperature of combustion gases. The analysis was conducted for different levels of the shock temperature, different thickness of applied TBC, produced from different kinds of materials.

Numerical and Experimental Investigation for Internal Cooling of Two Pass Gas Turbine Blades Channels Using Broken V Ribs

2014 ◽  
Author(s):  
Sourabh Kumar ◽  
R. S. Amano
Keyword(s):  
Gas Turbine ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Research Work ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Square Duct

Improvements in the thermal efficiency of a gas turbine can be obtained by operating it at high inlet temperatures. This high inlet temperature develops high thermal stresses on the turbine blades in addition to improving the performance. Cooling methodologies are implemented inside the blades to withstand those high temperatures. Four different combinations of broken 60° V ribs in cooling channel are considered. The research work investigates and compares numerically and experimentally, internal cooling of channels with broken V ribs. Local heat transfer in a square duct roughened with 60° V broken ribs is investigated for three different Reynolds numbers. Aspect ratio of the channel is taken to be 1:1. The pitch of the rib is considered to be 10 times the width of the rib, which is 0.0635 m. The square cross section of the channel is 0.508 × 0.508 m2 with 0.6096 m length. This study provides information about the best configuration of a broken V rib in a cooling channel.

Optimized Thermal Barrier Coating for Gas Turbine Blades

2019 ◽  
Vol 11 ◽  
pp. 912-919 ◽  
Author(s):  
Vishnu Sankar ◽  
PB. Ramkumar ◽  
Deepak Sebastian ◽  
Doyel Joseph ◽  
Jithu Jose ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Thermal Barrier Coating ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Gas Turbine Blades ◽  
Barrier Coating

Influence of Single Layer-Thickness on Residual Thermal Stresses in Sm2Zr2O7/YSZ Thermal Barrier Coatings

2013 ◽  
Vol 537 ◽  
pp. 97-100
Author(s):  
Ren Xi Hu ◽  
Xiao Ge Chen ◽  
Gang Li
Keyword(s):  
Shear Stress ◽  
Residual Stresses ◽  
Layer Thickness ◽  
Radial Stress ◽  
Thermal Stresses ◽  
Axial Stress ◽  
Single Layer ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Barrier Coating

In this paper, influence of single-layer thickness on residual stresses in Sm2Zr2O7/YSZ thermal barrier coating was analyzed by finite element method. Results show that the radial stress remains stable in x range 0-12mm, and it decreases abruptly at edge of the sample. The distribution of axial stress resembles that of radial stress, the shear stress increase abruptly at edge of sample. In three typical residual stresses, radial stress has the highest value, axial stress and shear stress can be ignored. The best thickness combination of Sm2Zr2O7/YSZ TBCs should be 0.1mm-NiCoCrAlY layer, 0.05-0.1mm -TGO, 0.1mm-YSZ and 0.9mm-Sm2Zr2O7

Thermal Shock Experiment and Simulation of Ceramic/Metal Gradient Thermal Barrier Coating

2007 ◽  
Vol 336-338 ◽  
pp. 1818-1822
Author(s):  
Jin Sheng Xiao ◽  
Kun Liu ◽  
Wen Hua Zhao ◽  
Wei Biao Fu
Keyword(s):  
Heat Transfer ◽  
Thermal Shock ◽  
Thermal Barrier Coating ◽  
Thermal Stresses ◽  
Initial Temperature ◽  
Thermal Barrier ◽  
Water Spray ◽  
Barrier Coating ◽  
Shock Experiment ◽  
Two Stages

A thermal shock experiment is designed to explore the thermal shock properties of ceramic/metal gradient thermal barrier coating. The specimens are heated up by oxygen-acetylene flame and cooled by water spray. The experiment procedure includes two stages, heating the specimen from the initial temperature 30°C for 40s, and then cooling for 20s. The heat transfer and the associated thermal stresses produced during the thermal shock procedure are simulated by finite element method. Experimental results indicated that the specimen of gradient coating behaves better in thermal shock experiments, which agree with the results of simulation.

Effect of Thermal Barrier Coating on Piston Crown for Compressed Natural Gas with Direct Injection Engine

2011 ◽  
Vol 52-54 ◽  
pp. 1830-1835 ◽  
Author(s):  
A.J. Helmisyah ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Natural Gas ◽  
Thermal Stresses ◽  
Direct Injection ◽  
Thermal Barrier ◽  
Compressed Natural Gas ◽  
Piston Crown ◽  
Barrier Coating ◽  
Temperature And Pressure

The top land of a piston normally known as the piston crown is an engine part that is continuously exposed to extreme temperature and pressure during combustion. For a compression ratio level, the compressed natural gas with a direct injection system (CNGDI) typically uses a range of compression ratio between gasoline and diesel engines, producing extremely high temperature and pressure which lead to high thermal stresses. Consequently, the piston crown is exposed to direct combustion due to the vertical movement of the piston, leading to various possible damages of thermal stresses. In contrast to a petrol fuelled internal combustion engine, natural gas combustion creates a dry condition in the combustion chamber, inducing cooling difficulties in the engine. Without good heat transfer, the piston crown materials will soon fail to withstand high temperature and operate effectively. Alternatively, any sort of insulation inside the combustion chamber such as applying ceramic coatings may protect the piston crown surface and affect the overall combustion process, as well as improving the engine performance and the exhaust emissions. By reducing the heat loss of a cylinder bore, a higher thermal efficiency of an engine can also be improved by applying a surface thermal insulation, namely; thermal barrier coating (TBC). Thus, in this study, a ceramic based TBC, yttria partially stabilised zirconia (YPSZ) coating was used to compare with conventional tin coated (Na2SnO3) and uncoated piston crown in terms of heat concentration. Moreover, a set of average value of combustion temperature of a CNGDI engine was selected. Detailed analyses using a finite element analysis (FEA) technique was utilised in order to determine the location of hotspots via distribution profiles of temperature. It was noted that the maximum heat flux of the uncoated piston crown was much higher than that of tin coated and YPSZ coated piston crown. Heat flux value reached about 62% of decrement due to lower conductivity levels of piston crown.

Thermal Barrier Systems and Multi-Layered Coatings Fabricated by Spark Plasma Sintering for the Protection of Ni-Base Superalloys

2010 ◽  
Vol 654-656 ◽  
pp. 1826-1831 ◽  
Author(s):  
Daniel Monceau ◽  
Djar Oquab ◽  
Claude Estournès ◽  
Mathieu Boidot ◽  
Serge Selezneff ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Turbine Blades ◽  
Thermal Barrier ◽  
Combustion Chambers ◽  
Temperature Oxidation ◽  
Multilayered Coatings ◽  
Barrier Coating ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Metallic Foils

Aeronautic gas turbine blades, vanes and combustion chambers are protected against high temperature oxidation and corrosion by single or multilayered coatings. These include environmental coatings, generally based on Pt-modified Ni aluminides or MCrAlY overlays (where M = Ni and/or Co), thermal barrier coating (TBC) systems including a ceramic thermally insulating layer, and abradable seals. The present work shows the ability of the Spark Plasma Sintering technique to rapidly develop new coatings compositions and microstructures. This technique allows combining powders and metallic foils on a superalloy substrate in order to obtain multilayered coatings in a single short production step. Fabrication of MCrAlY overlays with local Pt and/or Al enrichments is shown, as well as fabrication of coatings made of -PtAl2, -PtAl, α-AlNiPt2, martensitic and (Ni,Pt)Al or Pt-rich ’ phases, including their doping with reactive elements. The fabrication of a complete TBC system with a porous and adherent Yttria Stabilized Zirconia (YSZ) layer on a bond-coating is also demonstrated, as well as the fabrication of a CoNiCrAlY-based cermet coating for abradable seal application. Difficulties of fabrication are reviewed, such as Y segregation, risks of carburization, local over-heating, or difficulty to coat complex shaped parts. Solutions are given to overcome these difficulties.

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