The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Alain Batailly - One of the best experts on this subject based on the ideXlab platform.
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Sensitivity Analysis of Rotor/Stator Interactions Accounting for Wear and Thermal Effects within Low- and High-Pressure Compressor Stages
THE Coatings, 2020Co-Authors: Florence Nyssen, Alain BataillyAbstract:In the current design of turbomachines, engine performance is improved by reducing the clearances between the rotating components and the stator, which allows for loss decrease. Due to these clearance reductions, contact events may occur between the rotor and the stator. An Abradable Coating is deposited along the stator circumference as a sacrificial material to lower the contact severity. However, experiments highlighted the occurrence of rotor/stator interactions with high wear depth on the Abradable Coating as well as high temperature increases within the Abradable Coating following contacts. This work focuses on the sensitivity analysis of rotor/stator interactions with respect to the rotor angular speed and the initial clearances between the rotor and the stator, taking into account thermal effects within the Abradable Coating. Convergence analyses are first conducted to validate the numerical model. Then, after a calibration of the thermal model of the Abradable Coating based on two experimental test cases, the numerical model is used to investigate the cross effects of the angular speed and the initial clearances on the obtained rotor/stator interactions.
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Multi-physics numerical simulation of an experimentally predicted rubbing event in aircraft engines
Journal of Sound and Vibration, 2019Co-Authors: Quentin Agrapart, Florence Nyssen, Déborah Lavazec, Philippe Dufrenoy, Alain BataillyAbstract:Abstract This paper provides new insight on the simulation of blade-tip/casing rubbing events within aircraft engines accounting for thermomechanical effects within the casing. A multi-physics numerical strategy is presented in order to simulate an interaction experimentally witnessed on a full-scale low-pressure compressor. Experimental data are used for an accurate representation of the blade's incursion depth within the Abradable Coating. This numerical strategy combines Safran's in-house tool for rotor/stator interaction simulations with a finite element based thermomechanical analysis carried out with Ansys. This work underlines the distinct contributions of both dynamical and thermomechanical phenomena in the simulated interaction. Competition between wear and thermal expansions is investigated as well as their consequences on blade dynamics. The proposed numerical strategy yields an accurate description of the interaction phenomenon as wear patterns, critical speed, amplitude growth rate of the blade vibration and temperature levels may be predicted.
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Strongly Coupled Thermo-Mechanical Casing/Abradable Model for Rotor/Stator Interactions
Volume 7B: Structures and Dynamics, 2019Co-Authors: Florence Nyssen, Thibaut Vadcard, Elsa Piollet, Alain BataillyAbstract:Abstract Modern turbomachine designs feature reduced nominal clearances between rotating bladed-disks and their surrounding casings in order to improve the engine efficiency. Unavoidably, clearance reduction increases the risk of contacts between static and rotating components which may yield hazardous interaction phenomena. In this context, the deposition of an Abradable Coating along the casing inner surface is a common way to enhance operational safety while mitigating interaction phenomena thus allowing for tighter clearances. Nonetheless, interactions leading to unexpected wear removal phenomena between a bladed-disk and a casing with Abradable Coating have been observed experimentally. Beside of blade damages such as cracks resulting from high amplitudes of vibration, experimental observations included very significant temperatures increase, particularly within the Abradable Coating, to a point that thermo-mechanical effects may not be neglected anymore. The aim of this work is to investigate the numerical modeling of thermal effects in the Abradable Coating and the casing due to contact interactions. In particular, the proposed model provides insight on the sensitivity of engines to contact events when the plane had reduced tarmac times between two consecutive flights. A strongly coupled thermo-mechanical model of the casing and its Abradable Coating is first described. A 3D cylindrical mesh is employed, it may be decomposed in two parts: (1) along the casing contact surface, a cylindrical thermal mesh is constructed to compute the temperature elevation and heat diffusion in the three directions of space within the Abradable Coating, and (2) the casing itself is represented by a simplified cylindrical thermo-mechanical mesh to compute both temperature elevation and the induced deformations following temperature changes. This 3D hybrid mesh is combined with a mechanical mesh of the Abradable layer, dedicated to wear modeling and the computation of normal and tangential contact forces following blade/Abradable Coating impacts. The heat flux resulting from contact events is related to the friction forces and only heat transfer by conduction is considered in this work. In order to reduce computational times, the time integration procedure is twofold: the explicit time integration scheme featuring reduced time steps required for contact treatment is combined with a larger time step time integration scheme used for the casing thermo-mechanical model. An extensive validation procedure is carried out from a numerical standpoint, it underlines the convergence of the model with respect to time and space parameters.
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thermo mechanical modeling of Abradable Coating wear in aircraft engines
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2018Co-Authors: Florence Nyssen, Alain BataillyAbstract:In modern turbomachine designs, the nominal clearances between rotating bladed-disks and their surrounding casing are reduced to improve aerodynamic performances of the engine. This clearance reduction increases the risk of contacts between components and may lead to hazardous interaction phenomena. A common technical solution to mitigate such interactions consists in the deposition of an Abradable Coating along the casing inner surface. This enhances the engine efficiency while ensuring operational safety. However, contact interactions between blade-tips and an Abradable layer may yield unexpected wear removal phenomena. The aim of this work is to investigate the numerical modeling of thermal effects within the Abradable layer during contact interactions and compare it with experimental data. A dedicated thermal finite element mesh is employed. At each time step, a weak thermo-mechanical coupling is assumed: thermal effects affect the mechanics of the system, but the mechanical deformation of the elements has no effect on temperatures. Weak coupling is well appropriated in the case of rapid dynamics using small time step and explicit resolution schemes. Moreover, only heat transfer by conduction is considered in this work. To reduce computational times, a coarser spatial discretization is used for the thermal mesh comparing to the mechanical one. The time step used to compute the temperature evolution is larger than the one used for the mechanical iterations since the time constant of thermal effect is larger than contact events. The proposed numerical modeling strategy is applied on an industrial blade to analyze the impact of thermal effects on the blade's dynamics.
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Phenomenological modeling of Abradable wear in turbomachines
Mechanical Systems and Signal Processing, 2018Co-Authors: Bérenger Berthoul, Mathias Legrand, Alain Batailly, Laurent Stainier, Patrice CartraudAbstract:Abradable materials are widely used as Coatings within compressor and turbine stages of modern aircraft engines in order to reduce operating blade-tip/casing clearances and thus maximize energy efficiency. However, rubbing occurrences between blade tips and Coating liners may lead to high blade vibratory levels and endanger their structural integrity through fatigue mechanisms. Accordingly, there is a need for a better comprehension of the physical phenomena at play and for an accurate modeling of the interaction, in order to predict potentially unsafe events. To this end, this work introduces a phenomenological model of the Abradable Coating removal based on phenomena reported in the literature and accounting for key frictional and wear mechanisms including plasticity at junctions, ploughing, micro-rupture and machining. It is implemented within an in-house software solution dedicated to the prediction of full three-dimensional blade/Abradable Coating interactions within an aircraft engine low pressure compressor. Two case studies are considered. The first one compares the results of an experimental Abradable test rig and its simulation. The second one deals with the simulation of interactions in a complete low-pressure compressor. The consistency of the model with experimental observations is underlined, and the impact of material parameter variations on the interaction and wear behavior of the blade is discussed. It is found that even though wear patterns are remarkably robust, results are significantly influenced by Abradable Coating material properties.
Mathias Legrand - One of the best experts on this subject based on the ideXlab platform.
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Phenomenological modeling of Abradable wear in turbomachines
Mechanical Systems and Signal Processing, 2018Co-Authors: Bérenger Berthoul, Mathias Legrand, Alain Batailly, Laurent Stainier, Patrice CartraudAbstract:Abradable materials are widely used as Coatings within compressor and turbine stages of modern aircraft engines in order to reduce operating blade-tip/casing clearances and thus maximize energy efficiency. However, rubbing occurrences between blade tips and Coating liners may lead to high blade vibratory levels and endanger their structural integrity through fatigue mechanisms. Accordingly, there is a need for a better comprehension of the physical phenomena at play and for an accurate modeling of the interaction, in order to predict potentially unsafe events. To this end, this work introduces a phenomenological model of the Abradable Coating removal based on phenomena reported in the literature and accounting for key frictional and wear mechanisms including plasticity at junctions, ploughing, micro-rupture and machining. It is implemented within an in-house software solution dedicated to the prediction of full three-dimensional blade/Abradable Coating interactions within an aircraft engine low pressure compressor. Two case studies are considered. The first one compares the results of an experimental Abradable test rig and its simulation. The second one deals with the simulation of interactions in a complete low-pressure compressor. The consistency of the model with experimental observations is underlined, and the impact of material parameter variations on the interaction and wear behavior of the blade is discussed. It is found that even though wear patterns are remarkably robust, results are significantly influenced by Abradable Coating material properties.
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Full Three-Dimensional Rotor/Stator Interaction Simulations in Aircraft Engines With Time-Dependent Angular Speed
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2016Co-Authors: Alain Batailly, Mathias Legrand, Christophe PierreAbstract:Modern aircraft engine designs feature reduced clearances that may initiate structural contacts between rotating and static components. A numerical strategy dedicated to the simulation of such interactions is here enriched in order to account for time-dependent angular speeds. This contribution first details the evolution of the numerical strategy before validating the developments by comparing numerical results with experimental observations made on an industrial test bench. Further numerical investigations allow to assess the sensitivity of numerical results to acceleration and deceleration rates. Results, obtained with and without Abradable Coating, underline the fundamental nonlinear nature of the analyzed system. It is found that lower acceleration rates favour the arisal of interaction phenomena and that amplitudes of vibration at a given angular speed are generally lower when the blade decelerates.
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Full 3D Rotor/Stator Interaction Simulations in Aircraft Engines With Time-Dependent Angular Speed
Volume 7A: Structures and Dynamics, 2016Co-Authors: Alain Batailly, Mathias Legrand, Christophe PierreAbstract:Modern aircraft engine designs feature reduced clearances that may initiate structural contacts between rotating and static components. A numerical strategy dedicated to the simulation of such interactions is here enriched in order to account for time-dependent angular speeds. This contribution first details the evolution of the numerical strategy before validating the developments by comparing numerical results with experimental observations made on an industrial test bench. Further numerical investigations allow to assess the sensitivity of numerical results to acceleration and deceleration rates. Results, obtained with and without Abradable Coating, underline the fundamental nonlinear nature of the analysed system. It is found that lower acceleration rates favour the arisal of interaction phenomena and that amplitudes of vibration at a given angular speed are generally lower when the blade decelerates.
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unilateral contact induced blade casing vibratory interactions in impellers analysis for flexible casings with friction and Abradable Coating
Journal of Sound and Vibration, 2015Co-Authors: Alain Batailly, Mathias LegrandAbstract:Abstract This contribution addresses the vibratory analysis of unilateral contact induced structural interactions between a bladed impeller and its surrounding flexible casing. It extends the numerical developments exposed in a previous paper to flexible casings. The casing finite element model and the construction of the associated reduced-order model for efficient computations are first exposed in detail along with an extensive presentation of the smoothing strategy implemented on the contact interface. The proposed algorithms embedding unilateral contact conditions together with Abradable Coating removal are subsequently introduced and validated through a systematic analysis of (1) the nonlinear procedure for the computation of impeller/casing distances, (2) the treatment of three-dimensional friction and contact forces, (3) the correction of the displacements when unilateral contact or Abradable removal arises, and (4) the possible hybrid contact scenarii involving localized total removal of the Abradable Coating. Finally, two illustrative case studies show that the linear interaction condition, commonly considered for the safe design of impellers and casings in turbomachinery, may be advantageously combined with the presented numerical strategy in order to assess the actual importance of predicted critical speeds.
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Unilateral contact induced blade/casing vibratory interactions in impellers: Analysis for flexible casings with friction and Abradable Coating
Journal of Sound and Vibration, 2015Co-Authors: Alain Batailly, Mathias LegrandAbstract:Abstract This contribution addresses the vibratory analysis of unilateral contact induced structural interactions between a bladed impeller and its surrounding flexible casing. It extends the numerical developments exposed in a previous paper to flexible casings. The casing finite element model and the construction of the associated reduced-order model for efficient computations are first exposed in detail along with an extensive presentation of the smoothing strategy implemented on the contact interface. The proposed algorithms embedding unilateral contact conditions together with Abradable Coating removal are subsequently introduced and validated through a systematic analysis of (1) the nonlinear procedure for the computation of impeller/casing distances, (2) the treatment of three-dimensional friction and contact forces, (3) the correction of the displacements when unilateral contact or Abradable removal arises, and (4) the possible hybrid contact scenarii involving localized total removal of the Abradable Coating. Finally, two illustrative case studies show that the linear interaction condition, commonly considered for the safe design of impellers and casings in turbomachinery, may be advantageously combined with the presented numerical strategy in order to assess the actual importance of predicted critical speeds.
Corentin Delebarre - One of the best experts on this subject based on the ideXlab platform.
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High speed interaction between an Abradable Coating and a labyrinth seal in turbo-engine application
2020Co-Authors: Corentin Delebarre, Vincent Wagner, Jean-yves Paris, Gilles Dessein, Jean Denape, Julien Gurt-santanachAbstract:The design of gas turbine aims to enhance the engine efficiency by developing new materials able to work at higher temperatures, or to promote new technologies, fuel management and airflow direction. One solution is the reduction of clearance between rotary parts in turbomachinery air systems. This clearance reduction causes direct interactions in the secondary air system of a turbo-engine when a rotary seal, called labyrinth seal, rubs on the turbo-engine as a result of successive starts and stops, thermal expansions and vibrations. The purpose of the present paper is to study interaction phenomena between an Abradable material (Al-Si 6%) and a nickel alloy (718 alloy) during high speed contacts. A high speed test rig has been designed to simulate interactions between labyrinth seals and Abradable Coatings in similar operating conditions of turbo-engine in terms of geometries, rotational and linear velocities. A series of experiments has been carried out in order to get a first assessment under different turbo-engine operating conditions. Experimental results are presented using visual observations of test samples, quantitative approaches of interacting forces and micrographic observations. This work provides new basic data for a preliminary study of the interaction between a labyrinth seal teeth tips and its casing for turbo-engine applications.
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an experimental study of the high speed interaction between a labyrinth seal and an Abradable Coating in a turbo engine application
Wear, 2014Co-Authors: Corentin Delebarre, Vincent Wagner, Jean-yves Paris, Gilles Dessein, Jean Denape, Julien GurtsantanachAbstract:A new high-speed test rig was designed to simulate the interactions between labyrinth seals and Abradable Coatings in similar turbo-engine operating conditions. To determine a solution for turbo-engine efficiency enhancement, we investigated the clearance reduction between the rotary parts in air systems, the successive starts and stops, the thermal expansion and the vibrations that might cause direct rub interactions between a rotary seal, known as a labyrinth seal, and a turbo-engine housing coated with a sacrificial Abradable material. High interaction speeds from 0 to 130 m s−1 were obtained using a 5-axis milling machine fitted with a unique magnetic bearings spindle developed specifically for the study. The purpose of this paper is to study the interaction phenomena between an Abradable material (Al–Si 6%) and a nickel alloy (Alloy 718) to obtain a first contact assessment under different turbo-engine operating conditions. The experimental results are first presented by visual observations of the posttest samples, as specified by accurate profile measurements. A quantitative approach to the interaction forces recorded during the tests and micrographic observations complete the preliminary study. This work provides new basic data for a preliminary study of the interaction between labyrinth seal teeth tips and Abradable Coatings in turbo-engine applications.
Francois Maurice Garcin - One of the best experts on this subject based on the ideXlab platform.
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Conjectural bifurcation analysis of the contact-induced vibratory response of an aircraft engine blade
Journal of Sound and Vibration, 2015Co-Authors: Alain Batailly, Mathias Legrand, Antoine Millecamps, Francois Maurice GarcinAbstract:This paper deals with the numerical investigation of the unilateral contact-induced dynamics of a turbomachine blade rotating within a perfectly rigid yet distorted casing. This investigation is motivated by unelucidated vibratory behaviours observed experimentally. The simulations are based on an in-house time-marching strategy incorporating Lagrange multipliers for the unilateral contact treatment, as well as centrifugal stiffening and Abradable Coating removal. Significant extensions are proposed through the implementation of (1) aerodynamic loading on the blade and (2) post-processing techniques involving the empirical mode decomposition which provides fruitful insights on important transient phenomena. A thorough bifurcation analysis with and without aerodynamic loading highlights the existence of flip bifurcations with period-doubling and period-halving sequences over a broad angular speed range. Numerical simulations with external aerodynamic loading yield quasi-periodic and likely to be chaotic motions that could not be observed under vacuum. The proposed numerical investigations underline the key role of the aerodynamic loading in the blade dynamics and suggest that unexplained experimental vibratory behaviours are related to the vacuum conditions of the experiment.
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Snecma’s Viewpoint on the Numerical and Experimental Simulation of Blade-Tip/Casing Unilateral Contacts
Volume 7B: Structures and Dynamics, 2015Co-Authors: Antoine Millecamps, Mathias Legrand, Alain Batailly, Francois Maurice GarcinAbstract:Aircraft engine manufacturers are developping a new generation of turbojet engines featuring a lower impact on the environment, increased performances as well as reduced gas consumption. The efficiency of an engine is mostly driven by the operating clearance between the rotating parts and the stator. Accordingly, modern designs focus on the minimization of these clearances. In this context, unavoidable rotor imbalances or mistuning stemming from manufacturing processes as well as distortions resulting from thermal expansion or assembly conditions may generate blade-tip/casing contacts that are now considered as non-accidental operating conditions. In order to minimize the consequences of such events, an Abradable Coating is sprayed along the inner surface of the casing and acts as a fuse when the blade and the casing are in contact. However, even when an Abradable Coating is used, significant structural damages and wear as well as blade failures have been witnessed experimentally. The understanding of the physical phenomena at play called, on one hand, for throrough experimental investigations of rotor/stator contacts on full-scale stages of compressors and underlined that blade failure is mainly due to vibratory fatigue although the Abradable Coating is worn. On the other hand, numerical simulations have been performed to better understand the blade dynamics: over the last decade Snecma and its academic partners jointly developed a code for the simulation of contacts between rotor and stator: COROS. This code allows for the simulation of contacts — with a Lagrange multiplier contact treatment procedure — between full 3D models of engine components and accounts for Abradable Coating material removal. In particular, the simulation of experimental set-ups with COROS highlighted the correlation between the blade vibratory response and the Abradable material removal. Yet still an experimental code, this paper addresses the integration of COROS within the design process of aircraft engine blades at Snecma. The paper focuses on on-going research for the identification of critical parameters in the arising of interactions as early as the design stage of components. A particular attention is paid to the mechanical properties of the Abradable Coating for which both experimental and numerical investigations are detailed.© 2015 ASME
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Redesign of a High-Pressure Compressor Blade Accounting for Nonlinear Structural Interactions
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2014Co-Authors: Alain Batailly, Mathias Legrand, Antoine Millecamps, Sébastien Cochon, Francois Maurice GarcinAbstract:Recent numerical developments dedicated to the simulation of rotor/stator interaction involving direct structural contacts have been integrated within the Snecma industrial environment. This paper presents the first attempt to benefit from these developments and account for structural blade/casing contacts at the design stage of a high-pressure compressor blade. The blade of interest underwent structural divergence after blade/Abradable Coating contact occurrences on a rig test. The design improvements were carried out in several steps with significant modifications of the blade stacking law while maintaining aerodynamic performance of the original blade design. After a brief presentation of the proposed design strategy, basic concepts associated with the design variations are recalled. The iterated profiles are then numerically investigated and compared with respect to key structural criteria such as: (1) their mass, (2) the residual stresses stemming from centrifugal stiffening, (3) the vibratory level under aerodynamic forced response and (4) the vibratory levels when unilateral contact occurs. Significant improvements of the final blade design are found: the need for an early integration of nonlinear structural interactions criteria in the design stage of modern aircraft engines components is highlighted.Copyright © 2014 by ASME
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numerical experimental comparison in the simulation of rotor stator interaction through blade tip Abradable Coating contact
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2012Co-Authors: Alain Batailly, Mathias Legrand, Antoine Millecamps, Francois Maurice GarcinAbstract:Higher aircraft energy efficiency may be achieved by minimizing the clearance between the rotating blade tips and respective surrounding casing. A common technical solution consists in the implementation of an Abradable liner which improves both the operational safety and the efficiency of modern turbomachines. However, unexpected Abradable wear removal mechanisms were recently observed in experimental set-ups as well as duringmaintenance procedures. Based on a numerical strategy previously developed, the present study introduces a numerical-experimental comparison of such occurrence. Attention is first paid to the review and analysis of existing experimental results. Good agreement with numerical predictions is then illustrated in terms of critical stress levels within the blade as well as final wear profiles of the Abradable liner. Numerical results suggest an alteration of the Abradablemechanical properties in order to explain the outbreak of a divergent interaction. New blade designs are also explored in this respect and it is found that the interaction phenomenon is highly sensitive to (1) the blade geometry, (2) the Abradablematerial properties and (3) the distortion of the casing.
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Numerical-experimental comparison in the simulation of rotor/stator interaction through blade-tip/Abradable Coating contact
Journal of Engineering for Gas Turbines and Power-transactions of The Asme, 2012Co-Authors: Alain Batailly, Mathias Legrand, Antoine Millecamps, Francois Maurice GarcinAbstract:Higher aircraft energy efficiency may be achieved by minimizing the clearance between the rotating blade tips and respective surrounding casing. A common technical solution consists in the implementation of an Abradable liner which improves both the operational safety and the efficiency of modern turbomachines. However, unexpected Abradable wear removal mechanisms were recently observed in experimental set-ups as well as duringmaintenance procedures. Based on a numerical strategy previously developed, the present study introduces a numerical-experimental comparison of such occurrence. Attention is first paid to the review and analysis of existing experimental results. Good agreement with numerical predictions is then illustrated in terms of critical stress levels within the blade as well as final wear profiles of the Abradable liner. Numerical results suggest an alteration of the Abradablemechanical properties in order to explain the outbreak of a divergent interaction. New blade designs are also explored in this respect and it is found that the interaction phenomenon is highly sensitive to (1) the blade geometry, (2) the Abradablematerial properties and (3) the distortion of the casing.
Julien Gurtsantanach - One of the best experts on this subject based on the ideXlab platform.
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an experimental study of the high speed interaction between a labyrinth seal and an Abradable Coating in a turbo engine application
Wear, 2014Co-Authors: Corentin Delebarre, Vincent Wagner, Jean-yves Paris, Gilles Dessein, Jean Denape, Julien GurtsantanachAbstract:A new high-speed test rig was designed to simulate the interactions between labyrinth seals and Abradable Coatings in similar turbo-engine operating conditions. To determine a solution for turbo-engine efficiency enhancement, we investigated the clearance reduction between the rotary parts in air systems, the successive starts and stops, the thermal expansion and the vibrations that might cause direct rub interactions between a rotary seal, known as a labyrinth seal, and a turbo-engine housing coated with a sacrificial Abradable material. High interaction speeds from 0 to 130 m s−1 were obtained using a 5-axis milling machine fitted with a unique magnetic bearings spindle developed specifically for the study. The purpose of this paper is to study the interaction phenomena between an Abradable material (Al–Si 6%) and a nickel alloy (Alloy 718) to obtain a first contact assessment under different turbo-engine operating conditions. The experimental results are first presented by visual observations of the posttest samples, as specified by accurate profile measurements. A quantitative approach to the interaction forces recorded during the tests and micrographic observations complete the preliminary study. This work provides new basic data for a preliminary study of the interaction between labyrinth seal teeth tips and Abradable Coatings in turbo-engine applications.
