The Experts below are selected from a list of 309 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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Thermo-Mechanical Modeling of Abradable Coating Wear in Aircraft Engines
Journal of Engineering for Gas Turbines and Power, 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. 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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Investigations on thermo-mechanical modeling of abradable coating in the context of rotor/stator interactions
2017Co-Authors: Florence Nyssen, Alain BataillyAbstract:In modern turbomachine designs, the nominal clearances between rotating Bladed-disks and the surrounding casings are reduced to improve aerodynamical performances. But the reduction of nominal clearances significantly increases the risk of occurrence of contacts between static and rotating components and may lead to hazardous interaction phenomena. A common technical solution to mitigate this issue consists in the addition of an abradable coating on the casing inner surface. Even so, contact interactions between the Blade Tips and this abradable coating may yield unexpected abradable wear removal phenomena. For that reason, recent researches have focused on the numerical simulation of rotor/stator interactions with wear removal mechanism of operating clearances while neglecting thermal effects. However, high temperature areas due to contact occurrence have been observed experimentally. These high temperatures are suspected to generate a self-excitation of the system due the abradable dilatation. Accordingly, the aim of this work is to investigate the numerical modeling of thermal effects in the abradable coating due to contact interactions.
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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 study of a rotor/stator interaction case experimentally simulated with an industrial compressor
2012Co-Authors: Alain Batailly, Mathias Legrand, Millecamps Antoine, 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. Recently, unexpected abradable wear removal mechanisms were observed in experimental set-ups and duringmaintenance procedures. The present study introduces a numerical strategy capable to address this occurrence. After focusing on the analysis of the experimental results, the good agreement between experimental observations and numerical results is illustrated in terms of critical stress levelswithin the Blade as well as final wear profiles of the abradable liner. New Blade designs are also explored in order to assess the impact of Blade design on the outbreak of the interaction phenomenon. The prevalence of three dominant parameters in the interaction onset is shown: (1) Blade design, (2) abradable material mechanical properties and (3) the need for a global distortion of the casing to synchronize Blade-tip/abradable coating contacts.
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Assessment of reduced models for the detection of modal interaction through rotor stator contacts
Journal of Sound and Vibration, 2010Co-Authors: Alain Batailly, Mathias Legrand, Patrice Cartraud, Christophe PierreAbstract:Interactions through direct contact between Blade-Tips and outer casings in modern turbomachines require complex formulations and subsequent expensive computational efforts when the classical finite element method is considered. The construction of reduced-order models through component mode synthesis techniques usually improves the computational efficiency and may be used for fast parameter studies yielding a better knowledge of the phenomena of interest. In this highly nonlinear framework, the present study is dedicated to the investigation of the capabilities of fixed- and free-interface reduction strategies to handle accurately such problems through a realistic 2D model and complements former results involving a direct modal projection with respective strong kinematic restrictions. The equations of motion are solved using an explicit time integration scheme together with the Lagrange multiplier method where friction is accounted for. The presented work discusses the notions of both displacement and motion convergences and the possibility to conduct fast parameter studies with the use of relevant reduction bases. It also shows that kinematic restrictions artificially enhance the detection of modal interactions.
Inderjit Chopra - One of the best experts on this subject based on the ideXlab platform.
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analysis of a bending torsion coupled actuator for a smart rotor with active Blade Tips
Smart Materials and Structures, 2001Co-Authors: Andreas P F Bernhard, Inderjit ChopraAbstract:Active rotorBlade Tips offer an alternative approach to the challenge of main rotor active vibration control. The Tips are pitched with respect to the main Blade via a piezo-driven bending-torsion coupled actuator beam that runs down the length of the Blade. A Vlasov based, specialized one-dimensional finite beam element is developed to model the rotating actuator beam and is validated with the free-vibration and static forced response of 4:1 and 2:1 aspect ratio, bending-torsion coupled, active and passive plates. A one-eighth scale, reduced tip-speed rotor model (tip Mach 0.26), incorporating the bending-torsion actuator beam, has been previously hover tested (open loop). In these tests, Blade tip deflections of the order of 2° (half peak-to-peak) were achieved at 2, 3, 4, 5/rev with corresponding dynamic vertical Blade root shear variations of the order of 10-20% of the nominal Blade lift at 8° collective (CT/σ = 0.07). The test results are used to validate a coupled actuator and elastic rotorBlade model. The correlation of the predicted active Blade-tip pitch deflections and the experimental data is within 20%. The predicted values for the active vertical root shears are within the same margin for 4° and 6° collective.
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hover testing of active rotor Blade Tips using a piezo induced bending torsion coupled beam
Journal of Intelligent Material Systems and Structures, 1998Co-Authors: Andreas P F Bernhard, Inderjit ChopraAbstract:This paper presents the development of an active on-Blade vibration-reduction system using smart active Blade Tips (SABT), that are driven by a piezo-induced, bending-torsion coupled actuator. The actuator beam has a graphite substructure with surface bonded piezoceramic elements. A spanwise variation in both the bending-torsion coupling and the piezo element phasing is used to generate a pure tip twist. A small scale rotor, with 10% span active Tips, was tested on the hover stand, at a reduced tip speed of Mach 0.25. At a mean thrust loading (CT/σ) of 0.07, and for an activation of 100 Vrms, SABT deflection amplitudes from 1.8 deg at 2/rev to 2.25 deg at 4/rev were achieved (half peak-to-peak). The rotor normal force measurements show a distinct coupling of the activation with the first and second flap frequencies of the rotor. The corresponding dynamic thrust, generated by a single active tip, relative to the steady thrust, ranges from 4.5% at 2/rev to 8.3% at 5/rev. For a 1/rev excitation, the single a...
Ronald Scott Bunker - One of the best experts on this subject based on the ideXlab platform.
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axial turbine Blade Tips function design and durability
Journal of Propulsion and Power, 2006Co-Authors: Ronald Scott BunkerAbstract:An overview of the science and technology involved in today's turbine engines is presented with specific focus on the critical rotational-to-stationary interfaces comprising axial turbine Blade Tips. The purpose is to provide a concise informative review of turbine Blade tip functional, design, and durability issues. Neither a historical account nor a bibliography is presented. Attention is paid primarily to the most challenging Blade Tips in high-pressure, high-temperature gas turbine systems, although most of the science discussed applies equally well to Blade Tips in low-pressure turbines, as well as steam turbines. As such, a wide range of both aircraft engine and power generating turbine systems are considered. Basic functional requirements, turbine systems design aspects, and transient operational considerations affecting Blade Tips and affected by Blade Tips are discussed in light of the multidisciplinary tradeoffs involved in a successful design. The three dominant design philosophies for Blade Tips in practice today are presented with detailed examination of the aerodynamics, heat transfer, and cooling benefits and detractors. Finally, the in-service durability aspects of turbine Blade Tips are noted.
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A Review of Turbine Blade Tip Heat Transfer
Annals of the New York Academy of Sciences, 2006Co-Authors: Ronald Scott BunkerAbstract:This paper presents a review of the publicly available knowledge base concerning turbine Blade tip heat transfer, from the early fundamental research which laid the foundations of our knowledge, to current experimental and numerical studies utilizing engine-scaled Blade cascades and turbine rigs. Focus is placed on high-pressure, high-temperature axial-turbine Blade Tips, which are prevalent in the majority of today's aircraft engines and power generating turbines. The state of our current understanding of turbine Blade tip heat transfer is in the transitional phase between fundamentals supported by engine-based experience, and the ability to a priori correctly predict and efficiently design Blade Tips for engine service.
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effects of tip gap film injection from plain and squealer Blade Tips
ASME Turbo Expo 2004: Power for Land Sea and Air, 2004Co-Authors: Hasan Nasir, Ronald Scott Bunker, Srinath V Ekkad, Chander PrakashAbstract:The present study investigates the effect of orthogonal tip gap film injection from a plain and squealer tip of a HPT first stage rotor Blade. The pressure ratio (inlet total pressure to exit static pressure) for the cascade used was 1.2, and the experiments were run in a blow-down test rig with a four-Blade stationary linear cascade. The Reynolds number based on cascade exit velocity and axial chord length was 8.61×105 and the inlet and exit Mach numbers were 0.16 and 0.55, respectively. Five holes are located along the camber line of the Blade tip. A transient infrared technique was used to measure the local heat transfer coefficient and film effectiveness from a single transient test. All measurements were made for three blowing ratios of 1.0, 1.5, and 2.0. For all the cases, a small tip gap-to-Blade span ratio of 0.5% was used. The squealer depth-to-Blade span ratio of 4.16% was used for the squealer. Results show that the film injection has some effect for plain Tips but has no effect or negligible effect for squealer Tips.Copyright © 2004 by ASME
Andreas P F Bernhard - One of the best experts on this subject based on the ideXlab platform.
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analysis of a bending torsion coupled actuator for a smart rotor with active Blade Tips
Smart Materials and Structures, 2001Co-Authors: Andreas P F Bernhard, Inderjit ChopraAbstract:Active rotorBlade Tips offer an alternative approach to the challenge of main rotor active vibration control. The Tips are pitched with respect to the main Blade via a piezo-driven bending-torsion coupled actuator beam that runs down the length of the Blade. A Vlasov based, specialized one-dimensional finite beam element is developed to model the rotating actuator beam and is validated with the free-vibration and static forced response of 4:1 and 2:1 aspect ratio, bending-torsion coupled, active and passive plates. A one-eighth scale, reduced tip-speed rotor model (tip Mach 0.26), incorporating the bending-torsion actuator beam, has been previously hover tested (open loop). In these tests, Blade tip deflections of the order of 2° (half peak-to-peak) were achieved at 2, 3, 4, 5/rev with corresponding dynamic vertical Blade root shear variations of the order of 10-20% of the nominal Blade lift at 8° collective (CT/σ = 0.07). The test results are used to validate a coupled actuator and elastic rotorBlade model. The correlation of the predicted active Blade-tip pitch deflections and the experimental data is within 20%. The predicted values for the active vertical root shears are within the same margin for 4° and 6° collective.
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hover testing of active rotor Blade Tips using a piezo induced bending torsion coupled beam
Journal of Intelligent Material Systems and Structures, 1998Co-Authors: Andreas P F Bernhard, Inderjit ChopraAbstract:This paper presents the development of an active on-Blade vibration-reduction system using smart active Blade Tips (SABT), that are driven by a piezo-induced, bending-torsion coupled actuator. The actuator beam has a graphite substructure with surface bonded piezoceramic elements. A spanwise variation in both the bending-torsion coupling and the piezo element phasing is used to generate a pure tip twist. A small scale rotor, with 10% span active Tips, was tested on the hover stand, at a reduced tip speed of Mach 0.25. At a mean thrust loading (CT/σ) of 0.07, and for an activation of 100 Vrms, SABT deflection amplitudes from 1.8 deg at 2/rev to 2.25 deg at 4/rev were achieved (half peak-to-peak). The rotor normal force measurements show a distinct coupling of the activation with the first and second flap frequencies of the rotor. The corresponding dynamic thrust, generated by a single active tip, relative to the steady thrust, ranges from 4.5% at 2/rev to 8.3% at 5/rev. For a 1/rev excitation, the single a...
Setyawan Bekti Wibowo - One of the best experts on this subject based on the ideXlab platform.
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performances and stall delays of three dimensional wind turbine Blade plate models with helicopter like propeller Blade Tips
Mathematical Models and Methods in Applied Sciences, 2017Co-Authors: Sigit Iswahyudi, Muhammad Agung Bramantya, Setyawan Bekti WibowoAbstract:The research on three dimensional (3-D) wind turbine Blades has been introduced (Sutrisno, Prajitno, Purnomo, & B.W. Setyawan, 2016). In the current experiment, the 3-D wind turbine Blades would be fitted with helicopter-like Blade Tips and additional fins to the Blade hubs to demonstrate some laminarizing features. It was found that additional helicopter-like Blade tip to the turbine Blade creates strong laminar flows over the surface of the Blade Tips. Supplementary, finned hub, fitted to the Blade body, creates rolled-up vortex flows, weakens the Blade stall growth development, especially for Blades at high-speed wind. A proposed mathematical form of modified lifting line model has been developed to pursue further 3-d Blade development study of 3-d wind turbine Blade. Rolled up vortex effects, developed by finned of the base hub, has been acknowledged could demolish the turbulent region, as well as laminarize the stall domain to intensify the induced wind turbine Blade lift.