Academic literature on the topic 'Aero-thermo-mechanical approach'
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Journal articles on the topic "Aero-thermo-mechanical approach"
1
Tamsaout, Toufik, and El Hachemi Amara. "Numerical Simulation of Laser Bending of Thin Plate Stress Analysis and Prediction." Advanced Materials Research 227 (April 2011): 27–30. http://dx.doi.org/10.4028/www.scientific.net/amr.227.27.
Full textAbstract:
Laser forming is a technique consisting in the design and the construction of complex metallic work pieces with special shapes difficult to achieve with the conventional techniques. By using lasers, the main advantage of the process is that it is contactless and does not require any external force. It offers also more flexibility for a lower price. This kind of processing interests the industries that use the stamping or other costly ways for prototypes such as in the aero-spatial, automotive, naval and microelectronics industries. The analytical modeling of laser forming process is often complex or impossible to achieve, since the dimensions and the mechanical properties change with the time and in the space. Therefore, the numerical approach is more suitable for laser forming modeling. Our numerical study is divided into two models, the first one is a purely thermal treatment which allows the determination of the temperature field produced by a laser pass, and the second one consists in the thermo-mechanical coupling treatment. The temperature field resulting from the first stage is used to calculate the stress field, the deformations and the bending angle of the plate.
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Ragab, Mohamed, Hong Liu, Guan-Jun Yang, and Mohamed M. Z. Ahmed. "Friction Stir Welding of 1Cr11Ni2W2MoV Martensitic Stainless Steel: Numerical Simulation Based on Coupled Eulerian Lagrangian Approach Supported with Experimental Work." Applied Sciences 11, no. 7 (March 29, 2021): 3049. http://dx.doi.org/10.3390/app11073049.
Full textAbstract:
1Cr11Ni2W2MoV is a new martensitic heat-resistant stainless steel utilized in the manufacturing of aero-engine high-temperature bearing components. Welding of this type of steel using fusion welding techniques causes many defects. Friction stir welding (FSW) is a valuable alternative. However, few investigations have been performed on the FSW of steels because of the high melting point and the costly tools. Numerical simulation in this regard is a cost-effective solution for the FSW of this steel in order to optimize the parameters and to reduce the number of experiments for obtaining high-quality joints. In this study, a 3D thermo-mechanical finite element model based on the Coupled Eulerian Lagrangian (CEL) approach was developed to study the FSW of 1Cr11Ni2W2MoV steel. Numerical results of metallurgical zones’ shape and weld appearance at different tool rotation rates of 250, 350, 450 and 550 rpm are in good agreement with the experimental results. The results revealed that the peak temperature, plastic strain, surface roughness and flash size increased with an increase in the tool rotation rate. Lack-of-fill defect was produced at the highest tool rotation rate of 650 rpm. Moreover, an asymmetrical stir zone was produced at a high tool rotation rate.
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Broomfield, R. W., D. A. Ford, J. K. Bhangu, M. C. Thomas, D. J. Frasier, P. S. Burkholder, K. Harris, G. L. Erickson, and J. B. Wahl. "Development and Turbine Engine Performance of Three Advanced Rhenium Containing Superalloys for Single Crystal and Directionally Solidified Blades and Vanes." Journal of Engineering for Gas Turbines and Power 120, no. 3 (July 1, 1998): 595–608. http://dx.doi.org/10.1115/1.2818188.
Full textAbstract:
Turbine inlet temperatures over the next few years will approach 1650°C (3000°F) at maximum power for the latest large commercial turbofan engines, resulting in high fuel efficiency and thrust levels approaching 445 KN (100,000 lbs.). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements, and the development and use of rhenium (Re) containing high γ′ volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improves creep and thermo-mechanical fatigue strength, but also environmental properties including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4® containing 3 percent Re and CMSX®-10 containing 6 percent Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC® containing 3 percent Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50 percent of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines are scheduled to reach 60 percent in the U. S. ATS programme. Application experience to a total 1.3 million engine hours and 28,000 hours individual blade set service for CMSX-4 first stage turbine blades is reviewed for a small frame industrial engine.
4
Fazilati, Jamshid, Vahid Khalafi, and Hossein Shahverdi. "Three-dimensional aero-thermo-elasticity analysis of functionally graded cylindrical shell panels." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 5 (March 19, 2018): 1715–27. http://dx.doi.org/10.1177/0954410018763861.
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In the present paper, the aero-thermo-elastic behavior of a finite (three-dimensional) cylindrical curved panel geometry made from functionally graded material under high supersonic airflow is investigated. A generalized differential quadrature formulation is adopted while a steady-state through-the-thickness thermal field is also assumed. The geometry curvature and structural nonlinearity effects are included based on von Karman–Donnell strain–displacement relations. The nonlinear piston theory of third order is utilized in order to predict the unsteady aerodynamics loads induced from surrounding supersonic air stream. The functionally graded material is considered with temperature-dependent properties distributed in the thickness according to a power law function. Derived from the equilibrium equations, the aero-thermo-elastic governing equations are reduced to number of ordinary differential equations through using of the generalized differential quadrature method where the structure response is derived using fourth-order Runge–Kutta technique. The contribution of some parameters including flow Mach number, flow dynamic pressure, thickness temperature gradient, and functionally graded material volume fraction index on the flutter response as well as route-to-chaos behavior are reviewed. The calculated results are compared with those available in the literature wherever available and the accuracy and quality of the adopted generalized differential quadrature formulation in analyzing the aero-thermo-elastic behavior of three-dimensional functionally graded curved panels is shown. It reveals that using a three-dimensional approach, if any of Mach number and panel’s upper surface temperature is increased, the route-to-chaos behavior is reached through quasi-periodic motions.
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Haslam, Anthony, Abdullahi Abu, and Panagiotis Laskaridis. "A method for the assessment of operational severity for a high pressure turbine blade of an aero-engine." Open Engineering 5, no. 1 (December 16, 2015). http://dx.doi.org/10.1515/eng-2015-0041.
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Abstract This paper provides a tool for the estimation of the operational severity of a high pressure turbine blade of an aero engine. A multidisciplinary approach using aircraft/ engine performance models which provide inputs to a thermo-mechanical fatigue damage model is presented. In the analysis, account is taken of blade size, blade metal temperature distribution, relevant heat transfer coefficients and mechanical and thermal stresses. The leading edge of the blade is selected as the critical part in the estimation of damage severity for different design and operational parameters. The study also suggests a method for production of operational severity data for the prediction of maintenance intervals.
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P., Harinath S., Sharath Chandra GV, Shreyas P. M., and Kumar K. Gowda. "Verification of Over-Speed and Burst Margin Limits in Aero Engine Disc along with Low Cycle Fatigue Life." International Journal of Current Engineering and Technology 8, no. 02 (January 30, 2018). http://dx.doi.org/10.14741/ijcet/v.8.2.10.
Full textAbstract:
Aero engine rotor burst evaluation is one of the most important problems to be taken care off, whenever it comes to designing a turbo machinery disc. The consequences of a failure can be intense, since the disc fragments into multiple pieces and they are hurled away in all the possible direction at high speeds. Due to high thermo-mechanical loading conditions the disc is subjected to varying degrees of temperature from bore to rim. However, the centrifugal force dominates in the disc which ranges from 80%-90% and the rest can be treated as thermal and gas loads. The challenge lies at designing a disc for off-design conditions with their varying loads and duty cycles. In present work evaluation of safety limits and low-cycle fatigue (LCF) life estimation of an aero engine disc through classical methods and blending the terminologies with simulation engineering to arrive at a probable interpretation of number of duty cycles is carried out. The methodology compares the fatigue parameters involved in evaluation of disc life at off-design condition through sensitivity analysis. The design tool closely connects the flight certification FAA and EASA the regulating agencies for safety in air transportation vehicles. The off-design speed regulations through API and MIL handbook for material specification are considered to carry out design of experiments using finite element analysis approach
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Andreini, A., A. Bonini, G. Caciolli, B. Facchini, and S. Taddei. "Numerical Study of Aerodynamic Losses of Effusion Cooling Holes in Aero-Engine Combustor Liners." Journal of Engineering for Gas Turbines and Power 133, no. 2 (October 29, 2010). http://dx.doi.org/10.1115/1.4002040.
Full textAbstract:
Due to the stringent cooling requirements of novel aero-engines combustor liners, a comprehensive understanding of the phenomena concerning the interaction of hot gases with typical coolant jets plays a major role in the design of efficient cooling systems. In this work, an aerodynamic analysis of the effusion cooling system of an aero-engine combustor liner was performed; the aim was the definition of a correlation for the discharge coefficient (CD) of the single effusion hole. The data were taken from a set of CFD RANS (Reynolds-averaged Navier-Stokes) simulations, in which the behavior of the effusion cooling system was investigated over a wide range of thermo/fluid-dynamics conditions. In some of these tests, the influence on the effusion flow of an additional air bleeding port was taken into account, making it possible to analyze its effects on effusion holes CD. An in depth analysis of the numerical data set has pointed out the opportunity of an efficient reduction through the ratio of the annulus and the hole Reynolds numbers: The dependence of the discharge coefficients from this parameter is roughly linear. The correlation was included in an in-house one-dimensional thermo/fluid network solver, and its results were compared with CFD data. An overall good agreement of pressure and mass flow rate distributions was observed. The main source of inaccuracy was observed in the case of relevant air bleed mass flow rates due to the inherent three-dimensional behavior of the flow close to bleed opening. An additional comparison with experimental data was performed in order to improve the confidence in the accuracy of the correlation: Within the validity range of pressure ratios in which the correlation is defined (>1.02), this comparison pointed out a good reliability in the prediction of discharge coefficients. An approach to model air bleeding was then proposed, with the assessment of its impact on liner wall temperature prediction.
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Ullrich, Wolfram C., Yasser Mahmoudi, Kilian Lackhove, André Fischer, Christoph Hirsch, Thomas Sattelmayer, Ann P. Dowling, Nedunchezhian Swaminathan, Amsini Sadiki, and Max Staufer. "Prediction of Combustion Noise in a Model Combustor Using a Network Model and a LNSE Approach." Journal of Engineering for Gas Turbines and Power 140, no. 4 (October 31, 2017). http://dx.doi.org/10.1115/1.4038026.
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The reduction of pollution and noise emissions of modern aero engines represents a key concept to meet the requirements of the future air traffic. This requires an improvement in the understanding of combustion noise and its sources, as well as the development of accurate predictive tools. This is the major goal of the current study where the low-order thermo-acoustic network (LOTAN) solver and a hybrid computational fluid dynamics/computational aeroacoustics approach are applied on a generic premixed and pressurized combustor to evaluate their capabilities for combustion noise predictions. LOTAN solves the linearized Euler equations (LEE) whereas the hybrid approach consists of Reynolds-averaged Navier–Stokes (RANS) mean flow and frequency-domain simulations based on linearized Navier–Stokes equations (LNSE). Both solvers are fed in turn by three different combustion noise source terms which are obtained from the application of a statistical noise model on the RANS simulations and a post-processing of incompressible and compressible large eddy simulations (LES). In this way, the influence of the source model and acoustic solver is identified. The numerical results are compared with experimental data. In general, good agreement with the experiment is found for both the LOTAN and LNSE solvers. The LES source models deliver better results than the statistical noise model with respect to the amplitude and shape of the heat release spectrum. Beyond this, it is demonstrated that the phase relation of the source term does not affect the noise spectrum. Finally, a second simulation based on the inhomogeneous Helmholtz equation indicates the minor importance of the aerodynamic mean flow on the broadband noise spectrum.
Dissertations / Theses on the topic "Aero-thermo-mechanical approach"
1
Giuntini, Sabrina. "Transient modelling of whole gas turbine engine: an aero-thermo-mechanical approach." Doctoral thesis, 2018. http://hdl.handle.net/2158/1129189.
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In order to improve gas turbine performances, the operating temperature has been risen significantly over time. The possibility of applying more and more extreme operating conditions is mainly due to an efficient engine cooling. Secondary air system (SAS) design aims at obtaining the maximum efficiency with the minimum demand of mass flow bled from the compressor. Adequate cooling strategies have to be developed in order to guarantee suitable components lifespan and avoid failures. Anyway mass flows and pressure drops inside the secondary air system depend on the fluid-solid heat transfer itself, and in particular on the actual running clearances and gaps determined by the thermal expansion of components according to the current thermo-mechanical loads to which the engine is subjected. Due to changes in power generation market, the relevance of these issues increased considerably for large power generation gas turbines. In recent years their operating conditions have been deeply modified since more frequent and fast startups and shutdowns are required to meet electric load requirements. In order to manage thermal and mechanical stresses encountered in these repeated transient operations, and in order to monitor a number of parameters which should remain inside the pre-established operating ranges, the capability of predicting the thermal state of the whole engine represents a crucial point in the design process. Accurate prediction tools have to consider the strongly coupled phenomena occurring among SAS aerodynamic, metal-fluid heat transfer and deformations of the solid, in order to correctly estimate gaps and develop adequate SAS configurations. According to this, a Whole Engine Modelling (WEM) approach reproducing the entire machine in the real operating conditions is necessary in order to verify secondary air system efficiency, actual clearances, temperature peaks, structural integrity and all related aspects. It is here proposed a numerical procedure, developed in collaboration with Ansaldo Energia, aimed to perform transient thermal modelling calculations of large power generation gas turbines. The aerodynamic solution providing mass flows and pressures, and the thermo-mechanical analysis returning temperatures and material expansion are performed separately. The procedure faces the aero-thermo-mechanical problem with an iterative process with the aim of taking into consideration the mutual interaction of the different solutions, in a robust and modular analysis tool, combining secondary air system, thermal and mechanical analysis. The heat conduction in the solid and the fluid-solid heat transfer is computed by a customized version of the open source FEM solver CalculiX. The secondary air system is modelled by a customized version of the native CalculiX one-dimensional fluid network solver. Correlative and lower order methodologies for the fluid domain solution allows to speed up the design and analysis phase, while the presence of the iterative process allows to take into account the complex aero-thermo-mechanical interactions actually characterizing a real engine. A detailed description of the procedure will be reported with comprehensive discussions about the main fundamental modelling features introduced to cover all the aspects of interest in the simulation of a real machine. In order to assess the physical coherence of these features the procedure has been applied to two different test cases representative of typical real engine configurations, tested in a thermal transient cycle. The first one represents a simplified gas turbine arrangement tested with the aim of a first assessment from the point of view of the thermal loads evaluation. The second one is a portion of a real engine representative geometry, tested for the assessment of the interaction between SAS properties and the geometry deformations.
Book chapters on the topic "Aero-thermo-mechanical approach"
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Papadakis, L., A. Loizou, J. Risse, and S. Bremen. "A thermo-mechanical modeling reduction approach for calculating shape distortion in SLM manufacturing for aero engine components." In High Value Manufacturing: Advanced Research in Virtual and Rapid Prototyping, 613–18. CRC Press, 2013. http://dx.doi.org/10.1201/b15961-112.
Full textConference papers on the topic "Aero-thermo-mechanical approach"
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Giuntini, Sabrina, Antonio Andreini, and Bruno Facchini. "Finite Element Transient Modelling for Aero-Thermo-Mechanical Analysis of Whole Gas Turbine Engine." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91278.
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Abstract It is here proposed a numerical procedure aimed to perform transient aero-thermo-mechanical calculations of large power generation gas turbines. Due to the frequent startups and shutdowns that nowadays these engines encounter, procedures for multi-physics simulations have to take into account the complex coupled interactions related to inertial and thermal loads, and seal running clearances. In order to develop suitable secondary air system configurations, guarantee structural integrity and maintain actual clearances and temperature peaks in pre-established ranges, the overall complexity of the structure has to be reproduced with a whole engine modelling approach, simulating the entire machine in the real operating conditions. In the proposed methodology the aerodynamic solution providing mass flows and pressures, and the thermo-mechanical analysis returning temperatures and material expansion, are performed separately. The procedure faces the aero-thermo-mechanical problem with an iterative process with the aim of taking into account the complex aero-thermo-mechanical interactions actually characterizing a real engine, in a robust and modular tool, combining secondary air system, thermal and mechanical analysis. The heat conduction in the solid and the fluid-solid heat transfer are computed by a customized version of the open source FEM solver CalculiX®. The secondary air system is modelled by a customized version of the embedded CalculiX® one-dimensional fluid network solver. In order to assess the physical coherence of the presented methodology the procedure has been applied to a test case representative of a portion of a real engine geometry, tested in a thermal transient cycle for the assessment of the interaction between secondary air system properties and geometry deformations.
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Moroz, Leonid, Glenn Doerksen, Fernando Romero, Roman Kochurov, and Boris Frolov. "Integrated Approach for Steam Turbine Thermo-Structural Analysis and Lifetime Prediction at Transient Operations." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63547.
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In order to achieve the highest power plant efficiency, original equipment manufacturers (OEMs) continuously increase turbine working parameters (steam temperatures and pressures), improve components design and modify start-up cycles to reduce time while providing more frequent start-up events. All these actions result in much higher levels of thermo-stresses, a lifetime consumption of primary components and an increased demand for accurate thermo-structural and LCF simulations. In this study, some aspects of methodological improvement are analyzed and proposed in the frame of an integrated approach for steam turbine components thermo-structural analysis, reliability and lifetime prediction. The full scope of the engineering tasks includes aero/thermodynamic flow path and secondary flows analysis to determine thermal boundary conditions, detailed thermal/structural 2D and 3D FE models preparation, components thermal and stress-strain simulation, rotor-casing differential expansion and clearances analysis, and finally, turbine unit lifetime estimation. Special attention is paid to some of the key factors influencing the accuracy of thermal stresses prediction, specifically, the effect of ‘steam condensation’ on thermal BC, the level of detailing for thermal zones definition, thermal contacts and mesh quality in mechanical models. These aspects have been studied and validated against test data, obtained via a 30 MW steam turbine for combined cycle application based on actual start-up data measured from the power plant. The casing temperatures and rotor-stator differential expansion, measured during the commissioning phase of the turbine, were used for methodology validation. Finally, the evaluation of the steam turbine HPIP rotor lifetime by means of a low cycle fatigue approach is performed.
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Mogullapally, Venkateshwarlu, Shine Jyoth, Sanju Kumar, Rashmi Rao, and Rajeevalochanam B. A. "An Understanding of Stress and Pretension Behavior of Aero Engine Rotor Bolted Joint." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-59996.
Full textAbstract:
Abstract Bolted joints in gas turbines are used commonly to connect the parts of dissimilar materials to facilitate assembly, dis-assembly, and also to achieve modularity for advanced aero engines. In gas turbine engine, there are many rotating and stationary parts that are subjected to an extreme working environment. Bolted joints should have sufficient strength to support the mating parts such as safety critical fan/turbine discs, drums, and shaft assembly. Bolted joints are designed to avoid flange separation and slippage. This paper attempts to understand the challenges faced in designing a typical fan disc rotor plain flange type bolted assembly and structural integrity aspects under various thermo-mechanical operating loads. The understanding of stiffness of the bolt and joint members is necessary to evaluate the performance of the joint assembly. Based on literature, different approaches are used for estimating member stiffness to compare with finite element results. The effect of external loads such as thermo-mechanical loads on pretension behavior of bolted joint is studied with the help of standard commercial software platform ANSYS. Bolted joint preload loss has been assessed via the standard analytical method and validated with 3D finite element approach. This paper enables designer a quick understanding of rotor bolted joint behavior for finalization of gas turbine rotor layout, before going into complex and time consuming 3D finite element modelling and nonlinear stress analysis.
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Shrivastava, Sourabh, Prem Andrade, Vinay Carpenter, Ravindra Masal, Pravin Nakod, and Stefano Orsino. "Multi-Physics Simulation Based Approach for Life Prediction of a Gas Turbine Combustor Liner." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90897.
Full textAbstract:
Abstract Better life assessment of hot-components of an aero-engine can help improve its reliability and service life, while, reducing associated maintenance cost. Accurate prediction of Thermo-Mechanical Fatigue (TMF) is one of the crucial aspects of life prediction. Therefore, fully resolved simulation methodologies have gained attention as an ingredient for solving TMF problems owing to their potential for providing comprehensive insights into a system having hot components undergoing transient loading during operation. The present work focuses on a multi-physics simulation-based approach for the life-prediction of a representative gas-turbine combustor liner with an objective of providing a complete framework for TMF analysis of an actual aero-engine combustor liner. The presented methodology consists of a coupling between Computational Fluid Dynamics (CFD) and Finite Element Method (FEM). Thermal loads on the representative aero-engine combustor are predicted using Conjugate Heat Transfer (CHT) modeling in the CFD analyses for different operating conditions suitable for a flight cycle. A load cycle is then constructed using these thermal loads and is transferred to the structural analysis to evaluate the stresses in the liner. Results are obtained regarding spatially varying thermal expansion resulting in inelastic strains as governed by temperature and rate dependent material behavior. Stress and plastic strain history information from the structural analysis are processed to predict the life of different regions of the combustor liner. Different simulation methods for conjugate heat-transfer, load-cycle, material property extraction, thermal-stresses, and fatigue are evaluated, and an overall methodology involving accuracy and reasonable computational cost is proposed. The proposed methodology is numerically verified, and the verification results are presented in this work.
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Grasselt, David, Klaus Höschler, and Chetan Kumar Sain. "Fluid-Structure Interaction With a Fully Integrated Multiphysics Environment." In ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69078.
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The paper is focusing on Fluid-Structure Interaction (FSI) process modelling to look for the aero-elastic equilibrium with commercial software packages. The center of intention is to prove whether Ansys Workbench is capable to handle industrial size FSI applications on the one side and to identify possible excitation regions in the example case on the other. The three steps taken to come to a thermal-enhanced bidirectional fluid-structure approach within a fully integrated (monolithic) multiphysics environment are explained: aerodynamic assessment, thermo-structure mechanical setup and unidirectional coupling, as well as bidirectional coupling. Each subchapter describes the specific challenges, how they are solved and which results can be obtained or expected. The paper is focusing on the setup of a bidirectional process chain and does not set the thematic priority on detailed modelling and its results.
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Mohammed, M. B., C. J. Bennett, T. H. Hyde, and E. J. Williams. "The Evaluation of Coefficient of Friction for Representative and Predictive Finite Element Modelling of the Inertia Friction Welding." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59451.
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Inertia friction welding is the process in which stored kinetic energy in a flywheel is converted to heat by relative sliding movement between surfaces of axi-symmetric components to achieve a weld in the solid-state. The work in this paper relates to the production of dual-alloy shafts for aeroengines. Frictional characteristics determine the conditions at the weld interface and these are controlled by rotational velocity and applied axial pressure. So-called representative and predictive methods have been developed to evaluate friction conditions during the process and these are discussed in this paper. Weld data for the dissimilar weld between a high strength steel and a nickel-based super-alloy were provided by Rolls-Royce and MTU Aero Engines. The finite element software package DEFORM-2D is used to develop coupled thermo-mechanical axi-symmetric models. In previous work, methods employed to evaluate the efficiency of mechanical energy utilised during a weld, a parameter of great importance for numerical analysis, are not clear. Previous predictive approaches have employed test/weld data in one way or another to obtain the interface friction coefficient. This paper proposes a formula that incorporates the value of the mechanical energy efficiency of the welding machine into the calculation of coefficient of friction for representative modelling. It also introduces a predictive approach based on sub-layer flow theory to predict frictional behaviour during the welding process that is independent of test/weld data.
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Uppu, Nalini, Patrick F. Mensah, and Ravinder Diwan. "Two-Dimensional Thermal Performance Analysis of a Semi-Transparent Spectral Zirconia Thermal Barrier Coating." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62356.
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The performance of an aero engine can be increased in two ways: one by reducing the air requirement for the cooling of the turbine blades and secondly by increasing the turbine inlet temperature (TIT) that is operating temperature of the turbine blades. Taking into account the latter approach the blade material must withstand high temperatures of above 1350°C. For this enhancing purpose, protective coatings called the thermal barrier coatings (TBC) are being employed. The thermal barrier coating mainly consists of two layers; one is the metallic coating MCrAlY, which is the premiere layer over the substrate Ni based super alloy. The other is the ceramic layer made of Yttria Stabilized Zirconia (YSZ). Apart from these two layers, an intermediate layer of Al2O3 is formed by the oxidation of the aluminum in MCrAlY called the diffusion layer which also enhances the adhesion between the two layers. M stands for Nickel or Cobalt. The present study is an investigation on the in-situ thermal performance of TBCs by considering the ceramic layer as a semi-transparent media and varying its thickness and simultaneously increasing the operating temperature on its other boundary surface. The above thermal boundary value problem is modeled in 2-dimensions and solved numerically using the discrete ordinate model for radiative heat transfer in a commercial computational fluid dynamics and heat transfer software. Two samples of Ni based super alloy substrate with dimensions 40 × 100 × 3mm are considered; one sample with a thickness of 0.25 mm ceramic layer and the other sample with 1 mm coating thickness for transient thermal analysis. Simulated transient temperature histories are presented for use in a thermo-mechanical analysis in order to predict the failure modes in the TBC. The temperature distribution in TBC coating mainly depends on the radiative effects combined with heat conduction and convection and radiation at the material boundaries.
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Broomfield, Robert W., David A. Ford, Harry K. Bhangu, Malcolm C. Thomas, Donald J. Frasier, Phil S. Burkholder, Ken Harris, Gary L. Erickson, and Jacqueline B. Wahl. "Development and Turbine Engine Performance of Three Advanced Rhenium Containing Superalloys for Single Crystal and Directionally Solidified Blades and Vanes." In ASME 1997 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/97-gt-117.
Full textAbstract:
Turbine inlet temperatures over the next few years will approach 1650°C (3000°F) at maximum power for the latest large commercial turbo fan engines, resulting in high fuel efficiency and thrust levels approaching 445 kN (100,000 lbs). High reliability and durability must be intrinsically designed into these turbine engines to meet operating economic targets and ETOPS certification requirements. This level of performance has been brought about by a combination of advances in air cooling for turbine blades and vanes, design technology for stresses and airflow, single crystal and directionally solidified casting process improvements and the development and use of rhenium (Re) containing high γ′ volume fraction nickel-base superalloys with advanced coatings, including full-airfoil ceramic thermal barrier coatings. Re additions to cast airfoil superalloys not only improve creep and thermo-mechanical fatigue strength but also environmental properties, including coating performance. Re dramatically slows down diffusion in these alloys at high operating temperatures. A team approach has been used to develop a family of two nickel-base single crystal alloys (CMSX-4® containing 3% Re and CMSX®−10 containing 6% Re) and a directionally solidified, columnar grain nickel-base alloy (CM 186 LC® containing 3% Re) for a variety of turbine engine applications. A range of critical properties of these alloys is reviewed in relation to turbine component engineering performance through engine certification testing and service experience. Industrial turbines are now commencing to use this aero developed turbine technology in both small and large frame units in addition to aero-derivative industrial engines. These applications are demanding, with high reliability required for turbine airfoils out to 25,000 hours, with perhaps greater than 50% of the time spent at maximum power. Combined cycle efficiencies of large frame industrial engines is scheduled to reach 60% in the U.S. ATS programme. Application experience to a total 1.3 million engine hours and 28,000 hours individual blade set service for CMSX-4 first stage turbine blades is reviewed for a small frame industrial engine.
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Wingel, Christopher, Nicolas Binder, Yannick Bousquet, Jean-François Boussuge, Nicolas Buffaz, and Sébastien Le Guyader. "Influence of RANS Turbulent Inlet Set-Up on the Swirled Hot Streak Redistribution in a Simplified Nozzle Guide Vane Passage: Comparisons With Large-Eddy Simulations." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-78239.
Full textAbstract:
Abstract A high-pressure turbine is a complex component of a gas turbine from a thermo-mechanical point of view. In modern lean-burn combustion chambers, this complexity is enhanced with the presence of hot streaks together with swirl components and high levels of turbulence coming from the combustion chamber. These radial and azimuthal velocities and temperature distortions have a substantial impact either on the aerodynamics inside the high-pressure turbine or on the aero-thermal behavior of the vanes and blades. It is thus clear that the early development of a high-pressure turbine using numerical simulations must take into account swirled hot streaks. From a practical point of view, imposing the proper turbulence at the inlet boundary condition is not easy in classical Reynolds-Averaged Navier-Stokes (RANS) methods, where all the turbulence is modeled. This paper studies the redistribution of a swirled hot streak in the simplified case of a bent duct. This work focuses on turbulence modeling. High-fidelity Large-Eddy Simulation (LES) results are used as reference data to validate different RANS set-ups to predict the hot streak redistribution in terms of migration and diffusion. Results show that imposing the turbulent quantities from a LES causes an immediate destruction of the swirl components and a too-high total temperature diffusion in a RANS approach. It is found that the turbulent length scale, expressed in terms of μT/μ, plays a significant role in the aerodynamic and aero-thermal behavior of the flow. The optimal range for the value of μT/μ differs from what is encountered in the literature on a high-pressure turbine configuration. Also, imposing quantities at the inlet consistent with the LES or measurements does not improve the prediction of the trajectory of the swirl jet or the total temperature distribution. The anisotropy of turbulence is suspected to explain the failure of the usual RANS models.
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Michopoulos, J. G., C. Farhat, and C. Bou-Mosleh. "On Data-Driven Modeling and Simulation of Aero-Thermo-Mechanically Degrading Nonlinear Continuum Systems." In ASME 2006 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/detc2006-99737.
Full textAbstract:
Recent advances on data-driven application systems, sensor and computational technologies as well as long-term needs for efficient and accurate systemic behavior prediction monitoring in the context of realistic system design and maintenance, have brought degrading continuum systems modeling and simulation in the forefront of our activities. This paper outlines the initial steps of a methodology for applying a data-driven inverse-problem approach on the area of modeling mass-conserving degrading thermo-mechanical multi-domain nonlinear continuum structural and material systems. The methodology is applied for composite materials under simultaneous mechanical and thermal multi-field excitation and is based on mechatronic and computational automation. Furthermore, the multi-domain multiphysics modeling necessary for addressing the fluid-structure interaction involved in such systems is also discussed in the context of jet platforms with aerodynamically induced heating. Finally, simulation demonstrations are presented for the F-16 fighter jet and for a sensor-driven data solution reconstruction of an aircraft wing to demonstrate the potential for developing a material and structural health monitoring system based on he concept of dissipated energy density as a material health metric.