The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
A Matthews - One of the best experts on this subject based on the ideXlab platform.
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evaluation of Abradable Seal coating mechanical properties
Wear, 2009Co-Authors: A MatthewsAbstract:Three proprietary plasma-sprayed coatings, based on Ni–graphite, Al–Si–graphite and Al–Si–polyester, were chosen for evaluation by the use of a (low speed) scratch tester, as a means of assessing the performance of Abradable coatings. The scratch test behaviour was also correlated with the mechanical properties of the coatings (elastic modulus, microhardness and ultimate tensile strength). The results obtained were compared with those from industrial trials, to ascertain if the scratch test could be used as a relatively cheap and effective alternative to expensive engine trials. We have shown that the Progressive Abradability Hardness, abbreviated below as PAH, can be utilised as a measure of abradability in the scratch test, and can be related to the mechanical properties, in a manner consistent with engine test-bed findings. We have also found that the abradability and the PAH can change with scratch length due, we believe, to coating compression and densification ahead of the slider. In this work, the PAH has been related to coating hardness, ultimate tensile strength and elastic modulus.
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Evaluation of Abradable Seal coating mechanical properties
Wear, 2009Co-Authors: A MatthewsAbstract:International audienceThree proprietary plasma-sprayed coatings, based on Ni–graphite, Al–Si–graphite and Al–Si–polyester, were chosen for evaluation by the use of a (low speed) scratch tester, as a means of assessing the performance of Abradable coatings. The scratch test behaviour was also correlated with the mechanical properties of the coatings (elastic modulus, microhardness and ultimate tensile strength). The results obtained were compared with those from industrial trials, to ascertain if the scratch test could be used as a relatively cheap and effective alternative to expensive engine trials. We have shown that the Progressive Abradability Hardness, abbreviated below as PAH, can be utilised as a measure of abradability in the scratch test, and can be related to the mechanical properties, in a manner consistent with engine test-bed findings. We have also found that the abradability and the PAH can change with scratch length due, we believe, to coating compression and densification ahead of the slider. In this work, the PAH has been related to coating hardness, ultimate tensile strength and elastic modulus
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investigation of Abradable Seal coating performance using scratch testing
Surface & Coatings Technology, 2007Co-Authors: A MatthewsAbstract:Abstract Since the real conditions at the blade tip and the casing in a gas-turbine engine present a complex (very high speed) deformation situation that is difficult and expensive to replicate, we have evaluated the use of a (low speed) standard scratch tester, as a means of assessing the performance of Abradable coatings. Three proprietary plasma-sprayed coatings, Ni-graphite, Al–Si-graphite and Al–Si-polyester, were chosen for the tests. The scratch test behaviour was correlated with the mechanical properties of each coating (elastic modulus, microhardness and UTS (ultimate tensile strength)). Our results were compared with those from industrial trials, to ascertain if the scratch test could be used as a relatively cheap and effective alternative to expensive engine trials. We have shown that the “Progressive abradability hardness” (also called “specific grooving energy”), abbreviated below as “PAH", can be utilised as a measure of abradability in the scratch test, and can be related to the mechanical properties, in a manner consistent with engine test-bed findings. We have also found that the abradability and “PAH" can change with scratch length due to coating densification ahead of the slider, which is not easily revealed by other tests (such as the pendulum method). We therefore believe that scratch testing is a useful means of evaluating the likely in-service performance of Abradable coatings, prior to carrying out engine trials.
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Investigation of Abradable Seal coating performance using scratch testing
Surface and Coatings Technology, 2007Co-Authors: A MatthewsAbstract:International audienceSince the real conditions at the blade tip and the casing in a gas-turbine engine present a complex (very high speed) deformation situation that is difficult and expensive to replicate, we have evaluated the use of a (low speed) standard scratch tester, as a means of assessing the performance of Abradable coatings. Three proprietary plasma-sprayed coatings, Ni-graphite, Al–Si-graphite and Al–Si-polyester, were chosen for the tests. The scratch test behaviour was correlated with the mechanical properties of each coating (elastic modulus, microhardness and UTS (ultimate tensile strength)). Our results were compared with those from industrial trials, to ascertain if the scratch test could be used as a relatively cheap and effective alternative to expensive engine trials. We have shown that the " Progressive abradability hardness " (also called " specific grooving energy "), abbreviated below as " PAH", can be utilised as a measure of abradability in the scratch test, and can be related to the mechanical properties, in a manner consistent with engine test-bed findings. We have also found that the abradability and " PAH" can change with scratch length due to coating densification ahead of the slider, which is not easily revealed by other tests (such as the pendulum method). We therefore believe that scratch testing is a useful means of evaluating the likely in-service performance of Abradable coatings, prior to carrying out engine trials
Djar Oquab - One of the best experts on this subject based on the ideXlab platform.
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Thermal Barrier Systems and Multi-Layered Coatings Fabricated by Spark Plasma Sintering for the Protection of Ni-Base Superalloys
Materials Science Forum, 2010Co-Authors: Daniel Monceau, Mathieu Boidot, Djar Oquab, Serge Selezneff, Claude Estournès, Nicolas Ratel-ramondAbstract: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 ζ-PtAl2, ε-PtAl, α-AlNiPt2, martensitic and β-(Ni,Pt)Al or Pt-rich γ/γ' 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. © (2010) Trans Tech Publications.
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Thermal barrier systems and multi-layered coatings fabricated by spark plasma sintering for the protection of Ni-base superalloys
Materials Science Forum, 2010Co-Authors: Daniel Monceau, Mathieu Boidot, Djar Oquab, Serge Selezneff, Claude Estournès, Nicolas Ratel-ramondAbstract: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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Reactivity and microstructure evolution of a CoNiCrAlY/Talc cermet prepared by Spark Plasma Sintering
Surface and Coatings Technology, 2010Co-Authors: Nicolas Ratel-ramond, Claude Estournès, Daniel Monceau, Djar OquabAbstract:A mixture of CoNiCrAlY and talc powders is considered as a new candidate composition for Abradable Seal coating applications. Dense specimen having the composition of 1:20 weight ratio of talc with respect to CoNiCrAlY was prepared using the Spark Plasma Sintering (SPS) technique. The aim of the present article is to investigate the reactivity and microstructure evolution of the β/γ-CoNiCrAlY based cermet. The resulting microstructures were analysed and their compositions determined using standard analytical techniques such as SEM, TEM and X-ray diffraction. After fabrication, the bulk of the material is shown to contain a continuous oxide layer of MgAl2O4 at the periphery of metallic particles, resulting from the reaction between aluminium, which has diffused from the bulk of CoNiCrAlY grains, with magnesium and oxygen delivered during the high temperature decomposition of the talc phase. Thermodynamic calculations results are found to be consistent with the experimental observations. The oxidation behaviour at a high temperature of this cermet was also investigated. It was shown that at its external surface a continuous double layer is formed — one external film at the surface of the sample made of MgAl2O4 and the second one more internal in between the later and the cermet made of α-Al2O3. The oxide scale is protective with low oxidation kinetics typical of alpha alumina growth (kP = 1.8 ⋅ 10 − 7mg2 ⋅ cm − 4 ⋅ s − 1 at 1050 °C in flowing dry air).
Nicolas Ratel-ramond - One of the best experts on this subject based on the ideXlab platform.
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Thermal Barrier Systems and Multi-Layered Coatings Fabricated by Spark Plasma Sintering for the Protection of Ni-Base Superalloys
Materials Science Forum, 2010Co-Authors: Daniel Monceau, Mathieu Boidot, Djar Oquab, Serge Selezneff, Claude Estournès, Nicolas Ratel-ramondAbstract: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 ζ-PtAl2, ε-PtAl, α-AlNiPt2, martensitic and β-(Ni,Pt)Al or Pt-rich γ/γ' 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. © (2010) Trans Tech Publications.
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Thermal barrier systems and multi-layered coatings fabricated by spark plasma sintering for the protection of Ni-base superalloys
Materials Science Forum, 2010Co-Authors: Daniel Monceau, Mathieu Boidot, Djar Oquab, Serge Selezneff, Claude Estournès, Nicolas Ratel-ramondAbstract: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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Reactivity and microstructure evolution of a CoNiCrAlY/Talc cermet prepared by Spark Plasma Sintering
Surface and Coatings Technology, 2010Co-Authors: Nicolas Ratel-ramond, Claude Estournès, Daniel Monceau, Djar OquabAbstract:A mixture of CoNiCrAlY and talc powders is considered as a new candidate composition for Abradable Seal coating applications. Dense specimen having the composition of 1:20 weight ratio of talc with respect to CoNiCrAlY was prepared using the Spark Plasma Sintering (SPS) technique. The aim of the present article is to investigate the reactivity and microstructure evolution of the β/γ-CoNiCrAlY based cermet. The resulting microstructures were analysed and their compositions determined using standard analytical techniques such as SEM, TEM and X-ray diffraction. After fabrication, the bulk of the material is shown to contain a continuous oxide layer of MgAl2O4 at the periphery of metallic particles, resulting from the reaction between aluminium, which has diffused from the bulk of CoNiCrAlY grains, with magnesium and oxygen delivered during the high temperature decomposition of the talc phase. Thermodynamic calculations results are found to be consistent with the experimental observations. The oxidation behaviour at a high temperature of this cermet was also investigated. It was shown that at its external surface a continuous double layer is formed — one external film at the surface of the sample made of MgAl2O4 and the second one more internal in between the later and the cermet made of α-Al2O3. The oxide scale is protective with low oxidation kinetics typical of alpha alumina growth (kP = 1.8 ⋅ 10 − 7mg2 ⋅ cm − 4 ⋅ s − 1 at 1050 °C in flowing dry air).
Daniel Monceau - One of the best experts on this subject based on the ideXlab platform.
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Thermal Barrier Systems and Multi-Layered Coatings Fabricated by Spark Plasma Sintering for the Protection of Ni-Base Superalloys
Materials Science Forum, 2010Co-Authors: Daniel Monceau, Mathieu Boidot, Djar Oquab, Serge Selezneff, Claude Estournès, Nicolas Ratel-ramondAbstract: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 ζ-PtAl2, ε-PtAl, α-AlNiPt2, martensitic and β-(Ni,Pt)Al or Pt-rich γ/γ' 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. © (2010) Trans Tech Publications.
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Thermal barrier systems and multi-layered coatings fabricated by spark plasma sintering for the protection of Ni-base superalloys
Materials Science Forum, 2010Co-Authors: Daniel Monceau, Mathieu Boidot, Djar Oquab, Serge Selezneff, Claude Estournès, Nicolas Ratel-ramondAbstract: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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Reactivity and microstructure evolution of a CoNiCrAlY/Talc cermet prepared by Spark Plasma Sintering
Surface and Coatings Technology, 2010Co-Authors: Nicolas Ratel-ramond, Claude Estournès, Daniel Monceau, Djar OquabAbstract:A mixture of CoNiCrAlY and talc powders is considered as a new candidate composition for Abradable Seal coating applications. Dense specimen having the composition of 1:20 weight ratio of talc with respect to CoNiCrAlY was prepared using the Spark Plasma Sintering (SPS) technique. The aim of the present article is to investigate the reactivity and microstructure evolution of the β/γ-CoNiCrAlY based cermet. The resulting microstructures were analysed and their compositions determined using standard analytical techniques such as SEM, TEM and X-ray diffraction. After fabrication, the bulk of the material is shown to contain a continuous oxide layer of MgAl2O4 at the periphery of metallic particles, resulting from the reaction between aluminium, which has diffused from the bulk of CoNiCrAlY grains, with magnesium and oxygen delivered during the high temperature decomposition of the talc phase. Thermodynamic calculations results are found to be consistent with the experimental observations. The oxidation behaviour at a high temperature of this cermet was also investigated. It was shown that at its external surface a continuous double layer is formed — one external film at the surface of the sample made of MgAl2O4 and the second one more internal in between the later and the cermet made of α-Al2O3. The oxide scale is protective with low oxidation kinetics typical of alpha alumina growth (kP = 1.8 ⋅ 10 − 7mg2 ⋅ cm − 4 ⋅ s − 1 at 1050 °C in flowing dry air).
Baïz Sarah - One of the best experts on this subject based on the ideXlab platform.
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Experimental investigation of the blade/Seal interaction
'SAGE Publications', 2013Co-Authors: Baïz Sarah, Fabis Jacky, Boidin Xavier, Desplanques YannickAbstract:International audienceThe use of dynamic Seals to reduce the rotor/stator dynamic clearance in jet engine compressor stages leads to a higher rubbing occurrence between each blade and the coated inside of the casing. This article describes the development of a test rig capable to investigate forces and wear at the dynamic blade/Seal interaction, in conjunction with blade kinetics. Testing conditions are consistent with those of low-pressure compressor stages of jet engines: high-speed rubbing occurs between a TA6V blade substitute and an aluminium-silicon/boron nitride Abradable Seal. The platform is instrumented to allow a dynamic measurement of forces and displacements as well as high-speed imaging of the blade/Seal interaction zone throughout the experiment. The experiments showed that the blade incursion speed and penetration depth in the Abradable Seal both affect the amplitude and frequency of blade vibration. The amount and severity of blade incursions into the Abradable Seal have an impact on Seal wear type and intensity, which can in turn increase blade excitation
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Blade/Seal contacts in a jet engine : experimental contribution to the characterization of the mechanical behaviour of the Abradable Seal, and of its dynamic interaction with the blade, on a rotating device
2011Co-Authors: Baïz SarahAbstract:L’utilisation de revêtements Abradables pour assurer l’étanchéité dynamique des turboréacteurs est une solution répandue qui permet d’augmenter la fiabilité et le rendement aérodynamique des turboréacteurs. En fonctionnement, des touches inévitables entre le revêtement et le bout d’aubes de rotor peuvent être à l’origine d’une usure excessive du revêtement Abradable et/ou de la rupture d’aube. La simulation numérique de tels incidents butte sur un manque de connaissance des interactions aube/carter et des forces mises en jeu au contact, forces qui résultent notamment de couplages entre le frottement, l’usure du revêtement et des phénomènes vibratoires.Cette thèse a pour objectif de mieux appréhender les mécanismes d’interaction entre l’aube et le revêtement Abradable. Elle résulte d’une collaboration entre l’ONERA de Lille et le Laboratoire de Mécanique de Lille et concerne le revêtement de type Al-Si/hbN (Metco 320NS), couramment utilisé dans les compresseurs à basse pression.Les propriétés physico-chimiques et le comportement mécanique – notamment en dynamique – du revêtement Abradable sont étudiés. Compte-tenu d’une asymétrie du comportement en traction et en compression, l’exploitation en corrélation d’images numériques d’un essai original inspiré de l’essai Brésilien permet de rendre compte des mécanismes de dégradation. Le comportement tribologique est étudié sur tribomètre dans différentes configurations de contact. L’interaction entre l’aube et le revêtement ainsi que les couplages avec les vibrations d’aube sont investigués et caractérisés dans une configuration simplifiée et fortement instrumentée, sur un banc rotatif spécifique développé à l’ONERA de LilleAbradable Seals are extensively used in jet engines to ensure smaller rotor/stator dynamic clearances and lead to higher aerodynamic efficiencies. However, the resulting reduced rotor/stator gap can cause excessive Seal wear and/or a significant increase in rotor blades solicitation, both of which can be highly detrimental to the engine’s structural integrity. To allow numerical modelling of such accidental scenarios, there is a need to better comprehend the blade/Seal interactions as well as the contact forces involved and that can be influenced by the couplings occurring between friction, Seal wear and blade vibration.This thesis aims at contributing to a better understanding of the blade/Seal interaction mechanisms, in the framework of a cooperation between ONERA de Lille and the Laboratoire de Mécanique de Lille. The Abradable material is of Al-Si/hBN type (Metco 320NS), commonly used in low pressure compressors. The physicochemical properties and the mechanical behaviour – under static and dynamic loading – of this Abradable material are tested. Given the anti-symmetry of its tension and compression behaviour, use of the Digital Image Correlation technique to analyze an experiment derived from the Brazilian test allows qualification of the damage mechanisms. The friction behaviour of the Abradable Seal is studied on a tribometer using different contact configurations. Characterisation of the blade/Seal interaction and of some of the associated coupling phenomena is done on a dedicated and instrumented device developed at ONERA de Lill
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Etude expérimentale du contact aube/Abradable : contribution à la caractérisation mécanique des matériaux Abradables et de leur interaction dynamique sur banc rotatif avec une aube
HAL CCSD, 2011Co-Authors: Baïz SarahAbstract:Abradable Seals are extensively used in jet engines to ensure smaller rotor/stator dynamic clearances and lead to higher aerodynamic efficiencies. However, the resulting reduced rotor/stator gap can cause excessive Seal wear and/or a significant increase in rotor blades solicitation, both of which can be highly detrimental to the engine’s structural integrity. To allow numerical modelling of such accidental scenarios, there is a need to better comprehend the blade/Seal interactions as well as the contact forces involved and that can be influenced by the couplings occurring between friction, Seal wear and blade vibration.This thesis aims at contributing to a better understanding of the blade/Seal interaction mechanisms, in the framework of a cooperation between ONERA de Lille and the Laboratoire de Mécanique de Lille. The Abradable material is of Al-Si/hBN type (Metco 320NS), commonly used in low pressure compressors. The physicochemical properties and the mechanical behaviour – under static and dynamic loading – of this Abradable material are tested. Given the anti-symmetry of its tension and compression behaviour, use of the Digital Image Correlation technique to analyze an experiment derived from the Brazilian test allows qualification of the damage mechanisms. The friction behaviour of the Abradable Seal is studied on a tribometer using different contact configurations. Characterisation of the blade/Seal interaction and of some of the associated coupling phenomena is done on a dedicated and instrumented device developed at ONERA de LilleL’utilisation de revêtements Abradables pour assurer l’étanchéité dynamique des turboréacteurs est une solution répandue qui permet d’augmenter la fiabilité et le rendement aérodynamique des turboréacteurs. En fonctionnement, des touches inévitables entre le revêtement et le bout d’aubes de rotor peuvent être à l’origine d’une usure excessive du revêtement Abradable et/ou de la rupture d’aube. La simulation numérique de tels incidents butte sur un manque de connaissance des interactions aube/carter et des forces mises en jeu au contact, forces qui résultent notamment de couplages entre le frottement, l’usure du revêtement et des phénomènes vibratoires.Cette thèse a pour objectif de mieux appréhender les mécanismes d’interaction entre l’aube et le revêtement Abradable. Elle résulte d’une collaboration entre l’ONERA de Lille et le Laboratoire de Mécanique de Lille et concerne le revêtement de type Al-Si/hbN (Metco 320NS), couramment utilisé dans les compresseurs à basse pression.Les propriétés physico-chimiques et le comportement mécanique – notamment en dynamique – du revêtement Abradable sont étudiés. Compte-tenu d’une asymétrie du comportement en traction et en compression, l’exploitation en corrélation d’images numériques d’un essai original inspiré de l’essai Brésilien permet de rendre compte des mécanismes de dégradation. Le comportement tribologique est étudié sur tribomètre dans différentes configurations de contact. L’interaction entre l’aube et le revêtement ainsi que les couplages avec les vibrations d’aube sont investigués et caractérisés dans une configuration simplifiée et fortement instrumentée, sur un banc rotatif spécifique développé à l’ONERA de Lill
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Etude expérimentale du contact aube/Abradable (contribution à la caractérisation mécanique des matériaux Abradables et de leur interaction dynamique sur banc rotatif avec une aube)
2011Co-Authors: Baïz Sarah, Desplanques YannickAbstract:L utilisation de revêtements Abradables pour assurer l étanchéité dynamique des turboréacteurs est une solution répandue qui permet d augmenter la fiabilité et le rendement aérodynamique des turboréacteurs. En fonctionnement, des touches inévitables entre le revêtement et le bout d aubes de rotor peuvent être à l origine d une usure excessive du revêtement Abradable et/ou de la rupture d aube. La simulation numérique de tels incidents butte sur un manque de connaissance des interactions aube/carter et des forces mises en jeu au contact, forces qui résultent notamment de couplages entre le frottement, l usure du revêtement et des phénomènes vibratoires.Cette thèse a pour objectif de mieux appréhender les mécanismes d interaction entre l aube et le revêtement Abradable. Elle résulte d une collaboration entre l ONERA de Lille et le Laboratoire de Mécanique de Lille et concerne le revêtement de type Al-Si/hbN (Metco 320NS), couramment utilisé dans les compresseurs à basse pression.Les propriétés physico-chimiques et le comportement mécanique notamment en dynamique du revêtement Abradable sont étudiés. Compte-tenu d une asymétrie du comportement en traction et en compression, l exploitation en corrélation d images numériques d un essai original inspiré de l essai Brésilien permet de rendre compte des mécanismes de dégradation. Le comportement tribologique est étudié sur tribomètre dans différentes configurations de contact. L interaction entre l aube et le revêtement ainsi que les couplages avec les vibrations d aube sont investigués et caractérisés dans une configuration simplifiée et fortement instrumentée, sur un banc rotatif spécifique développé à l ONERA de LilleAbradable Seals are extensively used in jet engines to ensure smaller rotor/stator dynamic clearances and lead to higher aerodynamic efficiencies. However, the resulting reduced rotor/stator gap can cause excessive Seal wear and/or a significant increase in rotor blades solicitation, both of which can be highly detrimental to the engine s structural integrity. To allow numerical modelling of such accidental scenarios, there is a need to better comprehend the blade/Seal interactions as well as the contact forces involved and that can be influenced by the couplings occurring between friction, Seal wear and blade vibration.This thesis aims at contributing to a better understanding of the blade/Seal interaction mechanisms, in the framework of a cooperation between ONERA de Lille and the Laboratoire de Mécanique de Lille. The Abradable material is of Al-Si/hBN type (Metco 320NS), commonly used in low pressure compressors. The physicochemical properties and the mechanical behaviour under static and dynamic loading of this Abradable material are tested. Given the anti-symmetry of its tension and compression behaviour, use of the Digital Image Correlation technique to analyze an experiment derived from the Brazilian test allows qualification of the damage mechanisms. The friction behaviour of the Abradable Seal is studied on a tribometer using different contact configurations. Characterisation of the blade/Seal interaction and of some of the associated coupling phenomena is done on a dedicated and instrumented device developed at ONERA de LilleVILLENEUVE D'ASCQ-ECLI (590092307) / SudocSudocFranceF
