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Journal articles on the topic 'Aero-thermal model'
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1
Ba, Wei, Chunwei Gu, Xiaodong Ren, and Xuesong Li. "Convective cooling model for aero-thermal coupled through-flow method." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 2 (January 6, 2017): 133–44. http://dx.doi.org/10.1177/0957650916685911.
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The aero-thermal coupled phenomenon is significant in the modern cooled turbine, and it is necessary to consider the cooling effect and predict the coolant requirement in the through-flow design. A new cooling model was developed for the aero-thermal coupled through-flow method in this paper to predict the temperatures of both the pressure and suction surfaces of the blade. Based on the given blade temperature limitation rather than the mean blade surface temperature in the formal cooling model, the coolant requirement prediction can be more accurate. The equivalent blade thickness and heat exchange area estimation methods were further developed for blades with different cooling structures, and the estimations were carried out for each calculation station instead of the whole blade. The cooled blade was divided into a few calculation stations, and the heat transfer was studied for each station. Three operating conditions for the NASA-Mark II vane were selected for the verification. The predicted temperatures of both the pressure and suction surfaces agree with the experimental data, and the calculation results for the subsonic conditions are more accurate than the one for the transonic conditions.
2
Dai, Huaren, Zhe Chen, Wei Guo, and Ju Wang. "Thermal simulation model of aero-engine blade material forging simulation." Thermal Science 25, no. 4 Part B (2021): 3169–77. http://dx.doi.org/10.2298/tsci2104169d.
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During the high temperature forging process, the thermal parameters such as the temperature field and strain field in the blank have an important influence on the crack damage and micro-structure in the forging. We use the rigid viscoelastic finite element method to carry out the forging process of a heavy aero-engine blade the finite element numerical simulation was carried out to obtain the temperature field, strain field and forging load change law in the forging process with time, and on this basis, combined with the crack damage and repair mechanism and the re?crystallization structure evolution law, an optimization was proposed. The forging process plan. That is, the pre-forging is performed on the basis of the tolerance of the final forging dimension under pressure of 4 mm, the pre-forging temperature is 1160?C, and the final forging temperature is 1120?C. The actual forging process test verifies the feasibility of the process plan, which is the engineering of this process the application lays the scientific foundation.
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Qian, Wei, Yuguang Bai, Xiangyan Chen, and Taojun Lu. "Aero-servo-elastic analysis of a hypersonic aircraft." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 3 (August 23, 2017): 534–53. http://dx.doi.org/10.1177/1461348417725956.
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Aero-servo-elastic analysis of a complex hypersonic aircraft is presented in this paper. A structure geometry was designed and built based on the X-43A vehicle. First, a three-dimensional structural finite element model was proposed with effective two-dimensional elements, which can obtain effective modal analysis results without useless local modes. Second, computational fluid dynamic (CFD) simulation was adopted to find aero-heating distribution of thermal mode via this structure. Aero-heating effect was included to study thermal-modal characteristics of the present structure. Influence due to material characteristic change and thermal stress was studied. After structural finite element analysis was completed, flutter of the present vehicle was investigated. Aero-servo-elastic analysis was then started from the definition of an aero-servo-elastic closed-loop system. In this system, the present aircraft is treated as flexible structure, in which the control sensor on the aircraft received not only rigid motion signal but also elastic vibration signal, and this signal can translate into the deflection signal to form aerodynamic control force through this aero-servo control system, and this force can continually influence aerodynamic force. One of the most important steps for this analysis was computation of unsteady aerodynamic force of the present structure, and the related process was developed based on an effective fitting method. Finally, bode diagrams of pitching, rolling and yawing were investigated, form which the law of aero-servo stability of the X-43A vehicle can be observed and analyzed. It can be found from the results of this paper that effective investigation of aero-servo-elastic characteristics of a complex hypersonic aircraft should be based on accurate structural finite element modeling, modal analysis and flutter analysis. The proposed method in this paper can provide effective analysis process for the design of controller for hypersonic aircraft.
4
Ba, Wei, Xuesong Li, Xiaodong Ren, and Chunwei Gu. "Aero-thermal coupled through-flow method for cooled turbines with new cooling model." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 3 (September 25, 2017): 254–65. http://dx.doi.org/10.1177/0957650917731629.
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The aero-thermal–coupled phenomenon is significant in modern cooled turbines, and an aero-thermal coupled through-flow method has previously been developed by the authors for considering the influence of heat transfer and coolant mixing in through-flow design. However, the original cooling model is not capable of calculating the distribution of the coolant mass flow rate and pressure loss in complex cooling structures. Therefore, in this paper, a one-dimensional flow calculation for the internal coolant is introduced into the heat transfer calculation to further improve the through-flow cooling model. Based on various empirical correlations, the cooling model can be used to simulate different cooling structures, such as ribbed channels and cooling holes. Three operating conditions were selected for verification of the NASA-C3X vane, which has 10 internal radial cooling channels. The calculated Nusselt number of internal cooling channels strongly agrees with the experimental data, and the predicted blade surface pressure and temperature distributions at mid span are also in good agreement with the experimental data. The convergence history of the meridional velocity and blade surface temperature demonstrates effective convergence properties. Therefore, the aero-thermal–coupled through-flow method with the new cooling model can provide a reliable tool for cooled turbine through-flow design and analysis.
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Yazar, Isil, Tolga Yasa, and Emre Kiyak. "Simulation-based steady-state aero-thermal model for small-scale turboprop engine." Aircraft Engineering and Aerospace Technology 89, no. 2 (March 6, 2017): 203–10. http://dx.doi.org/10.1108/aeat-02-2015-0062.
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Purpose An aircraft engine control system consists of a large scale of control parameters and variables because of the complex structure of aero-engine. Monitoring and adjusting control variables and parameters such as detecting, isolating and reconfiguring the system faults/failures depend on the controller design. Developing a robust controller is based on an accurate mathematical model. Design/methodology/approach In this study, a small-scale turboprop engine is modeled. Simulation is carried out on MATLAB/Simulink for design and off-design operating conditions. Both steady-state and transient conditions (from idle to maximum thrust levels) are tested. The performance parameters of compressor and turbine components are predicted via trained Neuro-Fuzzy model (ANFIS) based on component maps. Temperature, rotational speed, mass flow, pressure and other parameters are generated by using thermodynamic formulas and conservation laws. Considering these calculated values, error calculations are made and compared with the cycle data of the engine at the related simulation conditions. Findings Simulation results show that the designed engine model’s simulation values have acceptable accuracy for both design and off-design conditions from idle to maximum power operating envelope considering cycle data. The designed engine model can be adapted to other types of gas turbine engines. Originality/value Different from other literature studies, in this work, a small-scale turboprop engine is modeled. Furthermore, for performance prediction of compressor and turbine components, ANFIS structure is applied.
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Jafari, Soheil, Ahmed Bouchareb, and Theoklis Nikolaidis. "Thermal Performance Evaluation in Gas Turbine Aero Engines Accessory Gearbox." International Journal of Turbomachinery, Propulsion and Power 5, no. 3 (August 26, 2020): 21. http://dx.doi.org/10.3390/ijtpp5030021.
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This paper presents a methodological approach for mathematical modelling and physics-based analysis of accessory gearbox (AGB) thermal behavior in gas turbine aero engines. The AGB structure, as one of the main sources of heat in gas turbine aero engines, is firstly described and its power losses will be divided into load-dependent and no-load dependent parts. Different mechanisms of heat generation are then identified and formulated to develop a toolbox for calculation of the churning, sliding friction, and rolling friction losses between contact surfaces of the AGB. The developed tool is also capable of calculating the heat loss mechanisms in different elements of the AGB, such as gears, bearings, and seals. The generated model is used to simulate and analyze the AGB thermal performance in the different flight phases in a typical flight mission, where the obtained results are validated against publicly available data. The analysis of the results confirms the effectiveness of the proposed method to estimate the heat loss values in the AGBs of gas turbine aero engines and to predict the thermal loads of the AGB in different flight phases. The developed tool enables the gas turbine thermal management system designers to deal with the generated heats effectively and in an optimal way.
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Ji, Fen Zhu, Xiao Xu Zhou, and Mi Tian. "Study on Thermal Management for Cooling System of Aero-Piston Engine." Advanced Materials Research 516-517 (May 2012): 452–56. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.452.
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A model of thermal management for cooling system of aero-piston engine was presented in this study. The models of main parts in this system were also founded. Based on the measured value of temperature and pressure in the cylinder, the heat transfer coefficient between gas-fired and the cylinder wall was calculated by using the empirical formula. A heat transfer boundary condition between fins and cooling air was determined according to various Reynolds number of the air flow. Moreover, the method of finite element analysis was utilized to calculate the temperature of cylinder block. In the specified working condition of some two-stroke piston engine used in the unmanned aerial vehicle (UAV), the calculation and analysis were made to study on the effect of aircrew speed and flight height on the cylinder block temperature, as well as the effect of cylinder block temperature on airscrew speed by the thermal management model. The calculation results show that, as the flight height rises, the cylinder block temperature increases accordingly when engine power and airscrew speeds are kept constant; however, at the same height, the higher the airscrew speed is, the lower cylinder block temperature will be. The cylinder block temperature should be kept stable by regulating the airscrew speed.
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Javiya, Umesh, John Chew, Nick Hills, and Timothy Scanlon. "Coupled FE–CFD thermal analysis for a cooled turbine disk." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 229, no. 18 (February 18, 2015): 3417–32. http://dx.doi.org/10.1177/0954406215572430.
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This paper presents transient aero-thermal analysis for a gas turbine disk and the surrounding air flows through a transient slam acceleration/deceleration “square cycle” engine test, and compares predictions with engine measurements. The transient solid–fluid interaction calculations were performed with an innovative coupled finite element (FE) and computational fluid dynamics (CFD) approach. The computer model includes an aero-engine high pressure turbine (HPT) disk, adjacent structure, and the surrounding internal air system cavities. The model was validated through comparison with the engine temperature measurements and is also compared with industry standard standalone FE modelling. Numerical calculations using a 2D FE model with axisymmetric and 3D CFD solutions are presented and compared. Strong coupling between CFD solutions for different air system cavities and the FE solid model led to some numerical difficulties. These were addressed through improvement of the coupling algorithm. Overall performance of the coupled approach is very encouraging giving temperature predictions as good as a traditional model that had been calibrated against engine measurements.
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Zheng, Min, Fan Shen, and Pei Luo. "Vibration Fatigue Analysis of the Structure under Thermal Loading." Advanced Materials Research 853 (December 2013): 559–64. http://dx.doi.org/10.4028/www.scientific.net/amr.853.559.
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The fatigue problem of structures under concurrent thermal and vibration loading has not been thoroughly studied even though it is common in applications of aero-engine combustor liners. Here we attempt to explore such a problem using a simplified combustor liner model that is implemented by the commercial finite element software ANSYS Workbench. The modal parameters at various temperatures are calculated and the fatigue behavior under stochastic base excitation and thermal environment are analyzed. The results show that thermal loading not only has an effect on dynamic characteristics but also reduces the vibration fatigue life of the structure.
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Wang, Jiang-Feng, Jia-Wei Li, Fa-Ming Zhao, and Xiao-Feng Fan. "Numerical method of carbon-based material ablation effects on aero-heating for half-sphere." Modern Physics Letters B 32, no. 12n13 (May 10, 2018): 1840011. http://dx.doi.org/10.1142/s0217984918400110.
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A numerical method of aerodynamic heating with material thermal ablation effects for hypersonic half-sphere is presented. A surface material ablation model is provided to analyze the ablation effects on aero-thermal properties and structural heat conduction for thermal protection system (TPS) of hypersonic vehicles. To demonstrate its capability, applications for thermal analysis of hypersonic vehicles using carbonaceous ceramic ablators are performed and discussed. The numerical results show the high efficiency and validation of the method developed in thermal characteristics analysis of hypersonic aerodynamic heating.
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Tang, Hong, Guo Guang Chen, and Hui Zhu He. "An Aero-Thermo-Elasticity Method Applied on the Supersonic Aircraft Model." Applied Mechanics and Materials 215-216 (November 2012): 438–42. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.438.
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Coupling between the vibration frequencies and the unsteady aerodynamic will reduce the flutter speed and ride quality through the aerodynamic heat transfer. As the flight speed improved, the aeroelastic analysis has become an essential means of aircraft design. The method of aero-thermo-elastic (ATE) analysis is coupled with aircraft aeroelastic analysis and thermal deformation, and is more realistic reflection of the actual flight of the aircraft. In this paper, an ATE analysis of aircraft adopted by computational fluid dynamics/computational structural dynamics (CFD/CSD) methods, and compared with the traditional analysis, to provide analytical tools for the supersonic aircraft design.
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Jasa, John P., Benjamin J. Brelje, Justin S. Gray, Charles A. Mader, and Joaquim R. R. A. Martins. "Large-Scale Path-Dependent Optimization of Supersonic Aircraft." Aerospace 7, no. 10 (October 20, 2020): 152. http://dx.doi.org/10.3390/aerospace7100152.
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Aircraft are multidisciplinary systems that are challenging to design due to interactions between the subsystems. The relevant disciplines, such as aerodynamic, thermal, and propulsion systems, must be considered simultaneously using a path-dependent formulation to assess aircraft performance accurately. In this paper, we construct a coupled aero-thermal-propulsive-mission multidisciplinary model to optimize supersonic aircraft considering their path-dependent performance. This large-scale optimization problem captures non-intuitive design trades that single disciplinary models and path-independent methods cannot resolve. We present optimal flight profiles for a supersonic aircraft with and without thermal constraints. We find that the optimal flight trajectory depends on thermal system performance, showing the need to optimize considering the path-dependent multidisciplinary interactions.
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Qiao, Lei, Jun-Qiang Bai, Jia-Kuan Xu, Jing-Lei Xu, and Yang Zhang. "Modeling of Supersonic/Hypersonic Boundary Layer Transition Using a Single-Point Approach." International Journal of Nonlinear Sciences and Numerical Simulation 19, no. 3-4 (June 26, 2018): 263–74. http://dx.doi.org/10.1515/ijnsns-2017-0011.
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AbstractDuring the process of aerodynamic shape design of supersonic and hypersonic space planes, laminar flow design and boundary layer transition prediction play important roles in aero-thermal numerical simulations and aero-thermal protection design. Therefore, in this study, a computational fluid dynamics compatible transition closure model for high speed laminar-to-turbulent transitional flows is formulated with consideration of the analysis results from stability theory. The proposed model contains two transport equations to describe the transition mechanism using local variables. Specifically, the eddy viscosity of laminar fluctuations and intermittency factor are chosen to be the characteristic parameters and modeled by transport equations. Accounting for the dominant instability modes at supersonic/hypersonic conditions, the first- and second- modes are modeled using local variables through the analysis of laminar self-similar boundary layers. Then, the present transition model is applied with compressibility corrected $k$-$\omega$ shear stress transport turbulence model. Thus, as the main significance of the current work, the present model is enabled to capture the overshoot phenomena as well as predict the transition onset position. Finally, comparisons between the predictions using the present model and the wind tunnel experimental results of several well-documented flow cases are provided to validate the proposed transition turbulence model.
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Bayona-Roa, Camilo, J. S. Solís-Chaves, Javier Bonilla, A. G. Rodriguez-Melendez, and Diego Castellanos. "Computational Simulation of PT6A Gas Turbine Engine Operating with Different Blends of Biodiesel—A Transient-Response Analysis." Energies 12, no. 22 (November 8, 2019): 4258. http://dx.doi.org/10.3390/en12224258.
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Instead of simplified steady-state models, with modern computers, one can solve the complete aero-thermodynamics happening in gas turbine engines. In the present article, we describe a mathematical model and numerical procedure to represent the transient response of a PT6A gas turbine engine operating at off-design conditions. The aero-thermal model consists of a set of algebraic and ordinary differential equations that arise from the application of the mass, linear momentum, angular momentum and energy balances in each engine’s component. The solution code has been developed in Matlab-Simulink® using a block-oriented approach. Transient simulations of the PT6A engine start-up have been carried out by changing the original Jet-A1 fuel with biodiesel blends. Time plots of the main thermodynamic variables are shown, especially those regarding the structural integrity of the burner. Numerical results have been validated against reported experimental measurements and GasTurb® simulations. The computer model has been capable to predict acceptable fuel blends, such that the real PT6A engine can be substituted to avoid the risk of damaging it.
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Yang, Jinguang, Min Zhang, and Yan Liu. "Numerical simulations and optimizations for turbine-related configurations." Thermal Science 24, no. 1 Part A (2020): 367–78. http://dx.doi.org/10.2298/tsci190404295y.
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In order to accelerate the numerical simulation and optimization of gas turbine-related configurations, a source based computational fluid dynamics (SCFD) approach is developed for flow and heat transfer simulations. Different sources de-pending on the fluid porosity at each grid node in the computational domain are introduced to the continuity, momentum, energy and turbulence model equations, so that both the fluid and solid regions can be solved as one region. In the present paper, test cases including a ribbed channel and a winglet shrouded turbine cascade with tip injection are investigated using the SCFD and CFD with body-fitted meshes. Impacts of grid clustering and turbulence model equation sources on the SCFD precision are examined. Numerical results show that the SCFD predicts consistent aero-thermal performance with the fluid dynamics with body-fitted meshes and experiments. The validated SCFD scheme is then employed in a response surface optimization of tip jet holes on the winglet shroud tip. A jet arrangement with the minimum energy loss and injection mass-flow rate is obtained, indicating that source based predictions can be applied to the preliminary aero-thermal design of turbine blades.
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Dong, Yiwei, Weiguo Yan, Tao Liao, Qianwen Ye, and Yancheng You. "Model characterization and mechanical property analysis of bimetallic functionally graded turbine discs." Mechanics & Industry 22 (2021): 4. http://dx.doi.org/10.1051/meca/2021001.
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In advanced propulsive systems, a turbine disc bears vast mechanical and thermal loads under its working conditions of high-temperature gradients and high rotational velocity.The complex working conditions of aero-engine turbine discs place stringent performance requirements on the materials used. With dual organizations and superior composite performances, bimetallic functionally graded turbine discs have become a focus in the research of high thrust-to-weight ratio aero-engines. To study the mechanical properties of new bimetallic functionally graded materials under service conditions, we propose a volumetric fraction expression and adjustable composition distribution parameters that are suitable for simulating the composition distribution of bimetallic functionally graded turbine discs. On this basis, a characterization model for functionally graded materials based on the analysis of the internal thermodynamic properties of bimetallic turbine discs is established. The thermodynamic properties and fatigue performances of functionally graded materials under service conditions are analysed. Mechanical property simulations of functionally graded turbine discs are performed using different composition distribution parameters, and reasonable ranges are determined for the various composition distribution parameters. The results show that bimetallic functionally graded turbine discs are suitable for high-stress-gradient and high-temperature-gradient environments with lower weights than those of current GH4169 alloy turbine discs.
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Yu, Ling, and Amit Shukla. "Comparison of Transient Response of a Skin Panel under Uniform and Non-Uniform Thermal Loading." Applied Mechanics and Materials 224 (November 2012): 33–38. http://dx.doi.org/10.4028/www.scientific.net/amm.224.33.
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This paper presents transient response of a skin panel under combined mechanical loading and provides a comparison of uniform and non-uniform thermal loading. A finite element model of a representative structural panel is used to evaluate the performance of an aero-structure subjected to severe aerodynamic heating and fluctuating pressure. This structure exhibits complex nonlinear response including thermal buckling and snap-through. In this study, uniform and non-uniform temperature distribution are used to understand the influence of spatial thermal distribution on the nonlinear response of the skin panel. It is shown that the parametric space snap-through boundary is significantly different for the two cases.
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Lou, De Cang, Wen Guo, Zhi Guo Wang, and Yong Hong Wang. "Integrated Thermal Management System Design for Advanced Propulsion System." Applied Mechanics and Materials 232 (November 2012): 723–29. http://dx.doi.org/10.4028/www.scientific.net/amm.232.723.
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Thermal management system (TMS) design is considered to be a key technology for advanced aero engines and supersonic or hypersonic propulsion systems. In this paper, the concepts of coupling flow and thermodynamic networks are proposed for TMS design. In this method, the propulsion system is considered to be a zero-dimensional flow system. Components, subsystems and hence the entire engine system can be modelled using some basic flow and thermodynamics networks. The platform for TMS design, ThermalM, is developed based on this model. As an example, modelling for a Turbine Based Combined Cycle (TBCC) thermal management system is described. Performance of the fuel heat exchanger in the network is discussed in detail. With the TMS design technology, performance of the advanced propulsion system can be analysed.
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Beniaiche, A., M. Nadir, M. Cerdoun, C. Carcasci, and B. Facchini. "Effect of turbulence models' choice on the aero-thermal flow numerical validations within a ribbed trailing edge geometry." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 233, no. 1 (May 7, 2018): 52–77. http://dx.doi.org/10.1177/0957650918772678.
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In this paper, the commercial ANSYS Fluent software was used to achieve a numerical survey of the effect of five (05) turbulence models’ formulation on the aero-thermal computational fluid dynamics validation of two 30:1 scaled models reproducing an original internal ribbed trailing edge prototype. Tests were conducted for stationary and rotation conditions, for Re = 10,000–40,000 and Ro = 0–0.23. Particle image velocimetry and thermochromic liquid crystal experimental data were employed to check the consistence computational fluid dynamics results qualitatively and quantitatively, aerodynamically and thermally, for various working conditions. Numerical predictions revealed that the choice of the turbulence model affects the accuracy of results. Concerning the shear stress transport k-w model, limiters defined in the eddy viscosity formulation induce a surplus estimation of the turbulence kinetic energy ( k) which leads to noticeable discrepancies in terms of velocity profiles and recirculation zones. Also, numerical calculations confirmed former experimental assumptions concerning origins of the aerodynamic structures and heat transfer's features, especially, those related to the increase of the cooling temperature balance efficiency, the appearance/disappearance of the horseshoe structures within the trailing edge region and velocities/boundary layers’ profile variations. The obtained results assist the understanding and the forecast of the flow field behavior, throughout the design process, by the assessment of the aerodynamic and thermal performances within the considered blade's cooling system.
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Schoenenborn, Harald, Ernst Ebert, Burkhard Simon, and Paul Storm. "Thermomechanical Design of a Heat Exchanger for a Recuperative Aeroengine." Journal of Engineering for Gas Turbines and Power 128, no. 4 (September 18, 2006): 736–44. http://dx.doi.org/10.1115/1.1850510.
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Within the framework programs of the EU for Efficient and Environmentally Friendly Aero-Engines (EEFEA) MTU has developed a highly efficient cross-counter flow heat exchanger for the application in intercooled recuperated aeroengines. This very compact recuperator is based on the profile tube matrix arrangement invented by MTU and one of its outstanding features is the high resistance to thermal gradients. In this paper the combined thermomechanical design of the recuperator is presented. State-of-the-art calculation procedures for heat transfer and stress analysis are combined in order to perform a reliable life prediction of the recuperator. The thermal analysis is based upon a 3D parametric finite element model generation. A program has been generated, which allows the automatic generation of both the material mesh and the boundary conditions. Assumptions concerning the boundary conditions are presented as well as steady state and transient temperature results. The stress analysis is performed with a FEM code using essentially the same computational grid as the thermal analysis. With the static temperature fields the static loading of the profile tubes is determined. From transient thermal calculations successive 3D temperature fields are obtained which enable the determination of creep life and LCF life of the part. Finally, vibration analysis is performed in order to estimate the vibration stress of the profile tubes during engine operation. Together with the static stress a Goodman diagram can be constructed. The combined analysis shows the high life potential of the recuperator, which is important for economic operation of a recuperative aero-engine.
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Marimuthu, S., D. Clark, J. Allen, AM Kamara, P. Mativenga, L. Li, and R. Scudamore. "Finite element modelling of substrate thermal distortion in direct laser additive manufacture of an aero-engine component." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 9 (December 21, 2012): 1987–99. http://dx.doi.org/10.1177/0954406212470363.
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The shape complexity of aerospace components is continuously increasing, which encourages researchers to further refine their manufacturing processes. Among such processes, blown powder direct laser deposition process is becoming an economical and energy efficient alternative to the conventional machining process. However, depending on their magnitudes, the distortion and residual stress generated during direct laser deposition process can affect the performance and geometric tolerances of manufactured components. This article reports an investigation carried out using the finite element analysis method to predict the distortion generated in an aero-engine component produced by the direct laser deposition process. The computation of the temperature induced during the direct laser deposition process and the corresponding distortion on the component was accomplished through a three-dimensional thermo-structural finite element analysis model. The model was validated against measured distortion values of the real component produced by direct laser deposition process using a Trumpf DMD505 CO2 laser. Various direct laser deposition fill patterns (orientation strategies/tool movement) were investigated in order to identify the best parameters that will result in minimum distortion.
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Reed, R. C., H. J. Stone, S. M. Roberts, and J. M. Robinson. "The development and validation of a model for the electron beam welding of aero-engine components." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 211, no. 6 (June 1, 1997): 421–28. http://dx.doi.org/10.1243/0954410971532785.
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Electron beam welding is used to manufacture high-integrity structures, for example compressor assemblies, for the latest generation of Rolls-Royce aero-engines. For such applications, the welding variables (for example welding current, voltage, beam focusing parameters) must be optimized, such that any distortion induced by the process is insignificant when compared to the dimensional tolerances allowed by the designers. Furthermore, the residual stresses induced by the process must be described and characterized, since these are required for estimates of component life. A model for such electron beam welding processes is described, along with the strategy adopted during its development. The basis of the model is a coupled thermal-mechanical finite element analysis. Particular attention is paid to (a) modelling of the heat source, (b) the frame of reference for the analysis, and (c) choice of finite element mesh. For the purposes of calibration and verification, a number of validatory experiments have been carried out. Typical results are presented and practical benefits are discussed.
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Rinaldi, Claudia, Valerio Bicego, and Pier Paolo Colombo. "Validation of CESI Blade Life Management System by Case Histories and in situ NDT." Journal of Engineering for Gas Turbines and Power 128, no. 1 (March 1, 2004): 73–80. http://dx.doi.org/10.1115/1.2056534.
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A life management system was developed for hot components of large industrial gas turbines, in the form of a software tool for predicting component lives under typical operational transients (normal and also abnormal) and steady-state periods. The method utilizes results of previous thermo-mechanical finite element and finite volume fluid mechanics analyses. The basic idea of this method is using data from structural and aero-thermal analyses (pressures and temperatures), blade life theory, and material properties as an input to algorithms, and using operational and historical data to validate the predicted damage amounts. The software developed in this project, of general applicability to all GT models, has been implemented with reference to the geometries, materials, and service conditions of a Fiat-Westinghouse model.
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Fueyo, N., V. Gambo´n, C. Dopazo, and J. F. Gonza´lez. "Computational Evaluation of Low NOx Operating Conditions in Arch-Fired Boilers." Journal of Engineering for Gas Turbines and Power 121, no. 4 (October 1, 1999): 735–40. http://dx.doi.org/10.1115/1.2818534.
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In the present paper, a computational model is used to simulate the aero-dynamic, thermal, and chemical conditions inside an arch-fired coal boiler. The model is based on the Eulerian-Eulerian concept, in which Eulerian conservation equations are solved both for the gas and the particulate phases. A NOx formation and destruction submodel is used to calculate the local concentration of NO. The model is used to simulate a range of operating conditions in an actual, 350 MW, arch-fired boiler, with the aim of reducing, using primary measures, the emissions of NOx. The model results shed some light on the relevant NOx-formation mechanisms under the several operating conditions. Furthermore, they correlate well quantitatively with the available field measurements at the plant, and reproduce satisfactorily the tendencies observed under the different operating modes.
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Shi, Xiujiang, Jiqiang Wu, Bin Zhao, Xuan Ma, and Xiqun Lu. "Mixed thermal elastohydrodynamic lubrication analysis with dynamic performance of aero ball bearing during start-up and shut-down." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 6 (January 23, 2020): 873–86. http://dx.doi.org/10.1177/1350650119900401.
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In this study, a coupling model is developed to include the aero ball bearing dynamic performance in the mixed thermal elastohydrodynamic lubrication analysis, and the low-speed and heavy-load conditions during start-up and shut-down are involved. Based on the bearing quasi-dynamics, the inside motion state of the main loading surface is obtained, and the mixed thermal elastohydrodynamic lubrication is conducted to get bearing lubrication state and properties. The numerical lubrication model under low-speed and heavy-load conditions is validated against published tested data, which reveal well consistency in central film thickness. The lubrication properties between a single ball and inner race during start-up have been studied, which indicate the lubrication film transforms from boundary lubrication to unsafe mixed thermal elastohydrodynamic lubrication, and then goes into safe lubrication. The lubrication properties of the balls at different azimuths have been investigated during shut-down and compared with those in start-up, which have a similar opposite changing trend, but not a simple invertible process. The time in boundary lubrication region during shut-down is shorter, and the ball number in boundary lubrication region gets less, which means the lubrication properties are relatively better. At last, the parametric study on mixed thermal elastohydrodynamic lubrication properties during shut-down has been carried out. It is found that the small bearing curve coefficient and increasing ball number can reduce the boundary lubrication time and improve the bearing lubrication.
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Filipek, Robert, Marek Danielewski, E. Tyliszczak, M. Pawełkiewicz, and S. Datta. "Thermal Stability of NiAl-Base Coatings for High Temperature Application." Defect and Diffusion Forum 237-240 (April 2005): 709–14. http://dx.doi.org/10.4028/www.scientific.net/ddf.237-240.709.
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Aluminide diffusion coatings act as a remedy against the aggressive environments in which modern aero-gas turbines operate. Platinum addition to basic aluminide coatings significantly improves the oxidation resistance of these coatings. The increase in operating temperatures of industrial energy systems and gas turbines, has led to the extensive use of coatings capable of providing improved service life. Interdiffusion plays a critical role in understanding the integrity of such coatings. The Danielewski-Holly model of interdiffusion which allows for the description of a wide range of processes (including processes stimulated by reactions at interfaces) is employed for studying of interdiffusion in the Pt-modified β-NiAl coatings. Using the inverse method the intrinsic diffusivities of Ni, Al and Pt were calculated. Such obtained diffusivities were subsequently used for modelling of thermal stability of Pt-modified aluminide coatings in air and in argon atmosphere.
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Sun, Hengchao, Guoding Chen, Yonghong Zhang, and Li’na Wang. "Theoretical and experimental studies on the motion and thermal states of oil droplet in a bearing chamber." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 230, no. 14 (February 24, 2016): 2596–614. http://dx.doi.org/10.1177/0954410016629690.
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Study on the motion and thermal states of oil droplet is an important part of research on the oil/air two-phase flow and heat transfer in an aero engine bearing chamber. In this paper, dimensional analysis is applied to the airflow analysis of bearing chamber. That makes the analysis model suitable for a wide range of geometric and operating conditions. Moreover, the temperature solution is added to the oil droplet motion analysis. That could promote the calculation accuracy of the droplet trajectory, velocity, and temperature. Firstly, the similarity criteria of the airflow in a bearing chamber are determined based on the dimensional analysis. The airflow distribution general formulas are proposed based on the numerical results of airflow velocity and temperature. The general formulas include 14 similarity criteria and are suitable for various geometric and operating conditions. The reliability of the general formulas is verified by some available experimental results. Secondly, the difference equations of the oil droplet velocity and temperature are listed by the difference method. The velocity and temperature of the droplet are obtained using a step-by-step method. The influence of droplet diameter, shaft rotational speed, air flow rate, and temperature on the oil droplet trajectory, velocity, and temperature are discussed. Thirdly, a test facility is built in order to investigate into the oil droplet motion and thermal states in a bearing chamber. The trajectory and velocity of the oil droplet are measured by the high-speed photography. Lastly, the proposed theoretical method about the oil droplet motion and thermal states is verified by above measurement results. The work in this paper may have a certain significance for perfecting the research system and improving the research level on the oil/air two-phase flow and heat transfer in an aero engine bearing chamber.
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Kumar, Amarnath, Prakash C. Patnaik, and Kuiying Chen. "Damage Assessment and Fracture Resistance of Functionally Graded Advanced Thermal Barrier Coating Systems: Experimental and Analytical Modeling Approach." Coatings 10, no. 5 (May 14, 2020): 474. http://dx.doi.org/10.3390/coatings10050474.
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Enhancement of stability, durability, and performance of thermal barrier coating (TBC) systems providing thermal insulation to aero-propulsion hot-section components is a pressing industrial need. An experimental program was undertaken with thermally cycled eight wt.% yttria stabilized zirconia (YSZ) TBC to examine the progressive and sequential physical damage and coating failure. A linear relation for parameterized thermally grown oxide (TGO) growth rate and crack length was evident when plotted against parameterized thermal cycling up to 430 cycles. An exponential function thereafter with the thermal cycling observed irrespective of coating processing. A phenomenological model for the TBC delamination is proposed based on TGO initiation, growth, and profile changes. An isostrain-based simplistic fracture mechanical model is presented and simulations carried out for functionally graded (FG) TBC systems to analyze the cracking instability and fracture resistance. A few realistic FG TBCs architectures were considered, exploiting the compositional, dimensional, and other parameters for simulations using the model. Normalized stress intensity factor, K1/K0 as an effective design parameter in evaluating the fracture resistance of the interfaces is proposed. The elastic modulus difference between adjacent FG layers showed stronger influence on K1/K0 than the layer thickness. Two advanced and promising TBC materials were also taken into consideration, namely gadolinium zirconate and lanthanum zirconate. Fracture resistance of both double layer and trilayer hybrid architectures were also simulated and analyzed.
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Yang, Xing, Zhenping Feng, and Terrence W. Simon. "Conjugate heat transfer modeling of a turbine vane endwall with thermal barrier coatings." Aeronautical Journal 123, no. 1270 (July 19, 2019): 1959–81. http://dx.doi.org/10.1017/aer.2019.56.
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ABSTRACTAdvanced cooling techniques involving internal enhanced heat transfer and external film cooling and thermal barrier coatings (TBCs) are employed for gas turbine hot components to reduce metal temperatures and to extend their lifetime. A deeper understanding of the interaction mechanism of these thermal protection methods and the conjugate thermal behaviours of the turbine parts provides valuable guideline for the design stage. In this study, a conjugate heat transfer model of a turbine vane endwall with internal impingement and external film cooling is constructed to document the effects of TBCs on the overall cooling effectiveness using numerical simulations. Experiments on the same model with no TBCs are performed to validate the computational methods. Round and crater holes due to the inclusion of TBCs are investigated as well to address how film-cooling configurations affect the aero-thermal performance of the endwall. Results show that the TBCs have a profound effect in reducing the endwall metal temperatures for both cases. The TBC thermal protection for the endwall is shown to be more significant than the effect of increasing coolant mass flow rate. Although the crater holes have better film cooling performance than the traditional round holes, a slight decrement of overall cooling effectiveness is found for the crater configuration due to more endwall metal surfaces directly exposed to external mainstream flows. Energy loss coefficients at the vane passage exit show a relevant negative impact of adding TBCs on the cascade aerodynamic performance, particularly for the round hole case.
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Kim, Young Jin, Minsung Kim, Man Yeong Ha, and June Kee Min. "Numerical Study on Surface Air-Oil Heat Exchanger for Aero Gas-Turbine Engine Using One-Dimensional Flow and Thermal Network Model." Transactions of the Korean Society of Mechanical Engineers B 38, no. 11 (November 1, 2014): 915–24. http://dx.doi.org/10.3795/ksme-b.2014.38.11.915.
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Zhao, Wei, Xiao Lin Han, and Qing Guo Fei. "Preliminary Research on the Aerothermoelastic Behaviours of Sweptback Wing." Applied Mechanics and Materials 138-139 (November 2011): 874–78. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.874.
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Natural modes and flutter of the sweptback wing are analyzed at different temperatures. Natural frequencies are reduced as temperature increasing, the temperature gradient in the structure tend to reduce model stiffness due to changing in material properties and development of thermal stress, which degrade the structure stability. Results in this paper show that the 1st~4thorder natural frequencies of sweptback wing in this paper decrease by about 12.09%, 15.06%, 14.31% and 12.57%respectively from room temperature to 450°C.The flutter frequency and velocity are also reduced as the decreasing of natural frequency due to the elevating of temperature by aero-heating; and the flutter frequency and velocity decrease by about 12.42% and 16.69% respectively as the temperature elevating from normal up to 450°C at Ma=3.0.
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Majila, Anuradha Nayak, Rajeev Jain, Chandru Fernando D., and S. Ramachandra. "Experimental and Numerical Correlation of Impact of Spherical Projectile for Damage Analysis of Aero Engine Component." Defence Science Journal 66, no. 2 (March 23, 2016): 193. http://dx.doi.org/10.14429/dsj.66.9130.
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<p>Studies the impact response of flat Titanium alloy plate against spherical projectile for damage analysis of aero engine components using experimental and finite element techniques. Compressed gas gun has been used to impart speed to spherical projectile at various impact velocities for damage studies. Crater dimensions (diameter and depth) obtained due to impact have been compared with finite element results using commercially available explicit finite element method code LS-DYNA. Strain hardening, high strain rate and thermal softening effect along with damage parameters have been considered using modified Johnson-Cook material model of LS-DYNA. Metallographic analysis has been performed on the indented specimen. This analysis is useful to study failure analysis of gas turbine engine components subjected to domestic object damage of gas turbine engine. </p><p> </p>
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Teodosio, Luigi, Giuseppe Alferi, Andrea Genovese, Flavio Farroni, Benedetto Mele, Francesco Timpone, and Aleksandr Sakhnevych. "A numerical methodology for thermo-fluid dynamic modelling of tyre inner chamber: towards real time applications." Meccanica 56, no. 3 (February 2, 2021): 549–67. http://dx.doi.org/10.1007/s11012-021-01310-w.
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AbstractThe characterization and reproduction of tyre behaviour for vehicle modelling is a topic of particular interest both for real-time driver in the loop simulations and for offline performance optimization algorithms. Since the accuracy of the tyre forces and moments can be achieved by the accurate physical modelling of all the phenomena concerning the tyre-road interaction, the link between the tyre thermal state and the tyre frictional performance turns into a crucial factor. An integrated numerical methodology, allowing to couple the full 3D CFD (Computational Fluid Dynamics) flux within the internal chamber of the tyre with an equivalent discrete 3D structure model, is proposed with the aim to completely represent the tyre thermodynamic convective behaviour in the steady-state operating conditions. 3D CFD model enables the evaluation of the internal distribution of the gas temperature and of the thermal powers exchanged at each sub-wall in detail. This allows to increase the reliability of the tyre thermodynamic modelling with a particular reference to the proper managing of the aero-thermal flow of the brake disc impact on the rim temperature and therefore on the internal gas dynamics in terms of temperature and pressure, being able to optimize the tyre overall dynamic performance in both warm-up and stabilized thermal conditions. The steady RANS (Reynolds Averaged Navier–Stokes) simulations have been performed employing the 3D CFD model in a wide range of angular velocities with the aim to calculate the convective thermal flux distributions upon rim and inner liner surfaces. The simulation results have been then exploited to derive the convective heat transfer coefficients per each sub domain to be employed within the real-time tyre physical thermal model, with the peculiar advantage of an enhanced model reliability for thermal characteristics. To validate the proposed methodology, the tyre thermal model outputs, in terms of temperatures of internal and external layers, have been validated towards the acquired ones within the specific routine performed on tyre force and moment test bench, confirming an excellent agreement with the experimental data in the entire range of operating conditions explored.
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Saleh, Zainab, Eldad J. Avital, and Theodosios Korakianitis. "Effect of in-service burnout on the transonic tip leakage flows over flat tip model." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 5 (September 30, 2019): 655–69. http://dx.doi.org/10.1177/0957650919877057.
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Un-shrouded turbine blades are more common than shrouded ones in gas turbine aero-engines since they reduce the weight and avoid the centrifugal loading caused by the blades’ shrouds. Despite these important advantages, the absence of the shroud leads to leakage flows across the tip gap and exposes the blade tip to high thermal load and thermal damages. In addition, the leakage flows can contribute up to 30% of the aerodynamic loss in a turbine stage. In this study, the effect of in-service burnout is explored using a fundamental flat tip model of a high-pressure gas turbine blade. This investigation is carried out both experimentally in a transonic wind tunnel and computationally using the Reynolds Averaged Navier-stokes approach at high-speed conditions. It is found that exposing the tip to the in-service burnout effect changes the leakage flow behaviour significantly when compared with the tip with sharp edges (i.e. the tip at the start of its operational life). Different flow acceleration, flow structure and shockwave pattern and interactions are captured for the round-edge flat tip (i.e. the tip exposed to in-service burnout). The effective tip gap is found to be much larger for the round-edge flat tip allowing more leakage flow into the tip gap which results into higher tip leakage losses in comparison to the sharp-edge tip. Experimental and computational flow visualisations, surface pressure distributions and discharge coefficient are given and analysed for several pressure ratios over the tip gap.
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Ранченко, Геннадий Степанович, and Анна Григорьевна Буряченко. "ПЕРСПЕКТИВИ РОЗВИТКУ ЕЛЕКТРОННИХ САУ ГТД." Aerospace technic and technology, no. 7 (November 10, 2018): 95–100. http://dx.doi.org/10.32620/aktt.2018.7.14.
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The analysis of the basic directions of electronic automatic control systems for aviation gas-turbine engines (FADEC) development is presented. This analysis is executed on the base of materials of the Scientific and Technical Congress of Aero-Engine Manufacturers. This Congress passed within the limits of the International engine forum in April 2018 in Moscow under aegis of the International association «Association of Aero-Engine Manufacturers» (ASSAD). The review of a modern condition of developing works of the specialized scientific enterprises in the field of application of onboard mathematical model «virtual engine» and introductions of wireless technologies in the aviation industry is given. It is noted, that design offices of manufacturers introduce as perspective decisions the modular unitized design for electronic automatic control systems and the “vibration passport” for engine type. The using of onboard mathematical model «virtual engine» provide the electronic automatic control systems with the possibility to apply the new controlling concepts and to compensate the failures of transducers which have information interchange with the automatic control system. The software «virtual engine» is developed by scientists of Central Institute of Aviation Motors (Moscow) and of Ukrainian National Aerospace University (Kharkov). The wireless technologies need the specialized power supply devices for wireless engines transducers. There is the tendency to use the engine energy (thermal engine energy, vibration engine energy) for such a power supply devices which is to be built on the base of thermoelectric generators, vibration generators and magnetic induction generators. The investigation of engine vibration characteristics in order to form the “vibration passport” for engine type is described. This passport is to be used for engine diagnostic during exploitation. There is described the method of electronic automatic control systems reliability confirmation by comparison with the prototypes (analogs) which is proposed by scientists of Central Institute of Aviation Motors.
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Gottlieb, Joshua, Roger Davis, and John Clark. "Conjugate rotor-stator interaction procedure for film-cooled turbine sections." Aircraft Engineering and Aerospace Technology 89, no. 3 (May 2, 2017): 365–74. http://dx.doi.org/10.1108/aeat-10-2014-0159.
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Purpose The authors aim to present a procedure for the parallel, steady and unsteady conjugate, Navier–Stokes/heat-conduction rotor-stator interaction analysis of multi-blade-row, film-cooled, turbine airfoil sections. A new grid generation procedure for multiple blade-row configurations, including walls, thermal barrier coatings, plenums, and cooling tubes, is discussed. Design/methodology/approach Steady, multi-blade-row interaction effects on the flow and wall thermal fields are predicted using a Reynolds’s-averaged Navier–Stokes (RANS) simulation in conjunction with an inter-blade-row mixing plane. Unsteady, aero-thermal interaction solutions are determined using time-accurate sliding grids between the stator and rotor with an unsteady RANS model. Non-reflecting boundary condition treatments are utilized in both steady and unsteady approaches at all inlet, exit and inter-blade-row boundaries. Parallelization techniques are also discussed. Findings The procedures developed in this research are compared against experimental data from the Air Force Research Laboratory’s turbine research facility. Practical implications The software presented in this paper is useful as both the design and analysis tool for fluid system and turbomachinery engineers. Originality/value This research presents a novel approach for the simultaneous solution of fluid flow and heat transfer in film-cooled rotating turbine sections. The software developed in this research is validated against experimental results for 2D flow, and the methods discussed are extendable to 3D.
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Wang, Qiang, Ya-Ping Hu, and Hong-Hu Ji. "An anisotropic porous media model for leakage analysis of finger seal." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 234, no. 2 (July 8, 2019): 280–92. http://dx.doi.org/10.1177/0954410019862080.
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Finger seal is a new type of compliant seal configuration, which is an important part of an aero-engine and its accessory systems. It has superior sealing performance compared with conventional labyrinth seals and a lower manufacturing cost than brush seals. However, numerical simulation of the leakage characteristics of an entitative finger seal structure are very difficult to implement, because the finger laminates are in close contact with one another and the radial deformation of the fingers caused by interference between seal and rotor as well as the centrifugal and thermal expansion of the rotor can change the geometric structure of seal. The published leakage analysis models of finger seal ignore the leakage throughout the interstices between fingers or finger laminates. In view of this, the authors propose an anisotropic porous media model for leakage analysis of finger seal. The model considers the effects of the seal structure parameters, upstream and downstream axial pressure differences and the fit status between seal and rotor. First, the equations of the model and their parameters were obtained by theoretical derivations, while the correction factors were determined based on experiment leakage data in the literature. Second, the accuracy of the model was validated by calculating the leakage of a known seal structure in the literature and comparing these results with the experimental data. At last, a comparison between the anisotropic and isotropic porous media model is carried out. The results of the validation examples show that the model can simulate the leakage of finger seal very well with the errors between numerical results and experimental data are less than 10% for two-thirds of the data points.
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Messenger, Andrew, and Thomas Povey. "Calibrated Low-Order Transient Thermal and Flow Models for Robust Test Facility Design." Journal of the Global Power and Propulsion Society 4 (July 3, 2020): 94–113. http://dx.doi.org/10.33737/jgpps/122270.
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This paper describes an upgrade to high temperature operation of the Engine Component AeroThermal (ECAT) facility, an established engine-parts facility at the University of Oxford. The facility is used for high-TRL research and development, new technology demonstration, and for component validation (typically large civil-engine HP NGVs). In current operation the facility allows Reynolds number, Mach number, and coolant-to-mainstream pressure ratio to be matched to engine conditions. Rich-burn or lean-burn temperature, swirl and turbulence profiles can also be simulated. The upgrade will increase the maximum inlet temperature to 600 K, allowing coolant-to-mainstream temperature ratio to be matched to engine conditions. This will allow direct validation of temperature ratio scaling methods in addition to providing a test bed in which all important non-dimensional parameters for aero-thermal behaviour are exactly matched. To accurately predict the operating conditions of the upgraded facility, a low order transient thermal model was developed in which the air delivery system and working section are modelled as a series of distributed thermal masses. Nusselt number correlations were used to calculate convective heat transfer to and from the fluid in the pipes and working section. The correlation was tuned and validated with experimental results taken from tests conducted in the existing facility. This modelling exercise informed a number of high-level facility design decisions, and provides an accurate estimate of the running conditions of the upgraded facility. We present detailed results from the low-order modelling, and discuss the key design decisions. We also present a discussion of challenges in the mechanical design of the working section, which is complicated by transient thermal stress induced in the working section components during facility start-up. The high-temperature core is unusually high-TRL for a research organisation, and we hope both the development and methodology will be of interest to engine designers and the research community.
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Hashmi, Muhammad Baqir, Tamiru Alemu Lemma, Shazaib Ahsan, and Saidur Rahman. "Transient Behavior in Variable Geometry Industrial Gas Turbines: A Comprehensive Overview of Pertinent Modeling Techniques." Entropy 23, no. 2 (February 22, 2021): 250. http://dx.doi.org/10.3390/e23020250.
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Generally, industrial gas turbines (IGT) face transient behavior during start-up, load change, shutdown and variations in ambient conditions. These transient conditions shift engine thermal equilibrium from one steady state to another steady state. In turn, various aero-thermal and mechanical stresses are developed that are adverse for engine’s reliability, availability, and overall health. The transient behavior needs to be accurately predicted since it is highly related to low cycle fatigue and early failures, especially in the hot regions of the gas turbine. In the present paper, several critical aspects related to transient behavior and its modeling are reviewed and studied from the point of view of identifying potential research gaps within the context of fault detection and diagnostics (FDD) under dynamic conditions. Among the considered topics are, (i) general transient regimes and pertinent model formulation techniques, (ii) control mechanism for part-load operation, (iii) developing a database of variable geometry inlet guide vanes (VIGVs) and variable bleed valves (VBVs) schedules along with selection framework, and (iv) data compilation of shaft’s polar moment of inertia for different types of engine’s configurations. This comprehensive literature document, considering all the aspects of transient behavior and its associated modeling techniques will serve as an anchor point for the future researchers, gas turbine operators and design engineers for effective prognostics, FDD and predictive condition monitoring for variable geometry IGT.
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Sha, Yun Dong, Hao Yuan Wang, and Huan Yu. "Nonlinear Response of Carbon-Carbon Laminated Panels to Random Acoustic Excitation under a Gradient Temperature Field." Applied Mechanics and Materials 696 (November 2014): 23–29. http://dx.doi.org/10.4028/www.scientific.net/amm.696.23.
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Future missions for aircraft will expose structures to severe thermal and acoustic loads. Efficient analysis methods for predicting nonlinear random response and fatigue life are urgently important. This paper presents a finite element model for analyzing nonlinear random dynamic behaviors of Carbon-Carbon composite panels under temperature gradients and Guassian excitations. The temperature distribution over the plate follows double sine curve. A finite element formulation combined with the equivalent linearization approach and normal mode method is established. The global system of equations is reduced to a set of nonlinear, coupled modal equations. Examples are given for an orthotropic C/C composite laminated panel at various combinations of temperatures gradients and sound pressure levels. Numerical results include RMS values of maximum deflection, time histories of deflection response and stress response, power spectrum densities, probability distribution functions and higher statistical moments. Numerical results verified all three types of panel motions for a simply supported orthotropic laminated plate: small-deflection random vibration about the initial equilibrium positions, snap-through motions between the two buckled positions, and nonlinear random response about new equilibrium positions after post-buckling. Numerical results will provide the important reference basis to aero engine structural integrity design and improving the structure dynamic strength and working life.
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Sun, Junfeng, Meihong Liu, Zhen Xu, Taohong Liao, Xiangping Hu, Yuxian Li, and Juan Wang. "Coupled Fluid–Solid Numerical Simulation for Flow Field Characteristics and Supporting Performance of Flexible Support Cylindrical Gas Film Seal." Aerospace 8, no. 4 (April 2, 2021): 97. http://dx.doi.org/10.3390/aerospace8040097.
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A new type of cylindrical gas film seal (CGFS) with a flexible support is proposed according to the working characteristics of the fluid dynamic seal in high-rotational-speed fluid machinery, such as aero-engines and centrifuges. Compared with the CGFS without a flexible support, the CGFS with flexible support presents stronger radial floating characteristics since it absorbs vibration and reduces thermal deformation of the rotor system. Combined with the structural characteristics of a film seal, an analytical model of CGFS with a flexible wave foil is established. Based on the fluid-structure coupling analysis method, the three-dimensional flow field of a straight-groove CGFS model is simulated to study the effects of operating and structural parameters on the steady-state characteristics and the effects of gas film thickness, eccentricity, and the number of wave foils on the equivalent stress of the flexible support. Simulation results show that the film stiffness increases significantly when the depth of groove increases. When the gas film thickness increases, the average equivalent stress of the flexible support first decreases and then stabilizes. Furthermore, the number of wave foils affects the average foils thickness. Therefore, when selecting the number of wave foils, the support stiffness and buffer capacity should be considered simultaneously.
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Taheri, Yaser, Meran Zargarabadi, and Mehdi Jahromi. "Multi-objective optimization of three rows of film cooling holes by genetic algorithm." Thermal Science, no. 00 (2020): 230. http://dx.doi.org/10.2298/tsci190805230t.
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Aero-thermal optimization on multi-rows of film cooling over a flat plate has been performed to optimize the inclination angles. Hence three cylindrical holes with injection angles of ?, ?, and ? have been considered. The cooling hole has a 3 mm diameter and an inclined angle between 25 to 35 degrees. Numerical simulations were performed at a fixed density ratio of 1.25 and blowing ratio of 0.5. The control-volume method with a SIMPLEC algorithm has been used to solve the steady-state RANS equations with SST k-? turbulent model. The injection angles of the holes are selected as the design variables to perform the optimization of three rows of film cooling. In order to evaluate the performance of holes arrangement, two objective functions are defined based on aerodynamic losses and adiabatic film cooling effectiveness. The curve fitting method (CFM) is used to find the optimal point of objective functions. The optimizations have been performed using the genetic algorithm (GA) method. Results of the present study show that the best performance of three rows of cooling holes was achieved in inclined angles 25.45, 32.85 and 33.1.
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Błachnio, Józef, and Wojciech I. Pawlak. "Non-Uniformity of the Combustor Exit Flow Temperature in Front of the Gas Turbine." Acta Mechanica et Automatica 8, no. 4 (December 1, 2014): 209–13. http://dx.doi.org/10.2478/ama-2014-0038.
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Abstract Various types of damages to gas-turbine components, in particular to turbine blades, may occur in the course of gas turbine operation. The paper has been intended to discuss different forms of damages to the blades due to non-uniformity of the exit flow temperature. It has been shown that the overheating of blade material and thermal fatigue are the most common reasons for these damages. The paper presents results from numerical experiments with use of the computer model of the aero jet engine designed for simulations. The model has been purposefully modified to take account of the assumed non-homogeneity of the temperature field within the working agent at the turbine intake. It turned out that such non-homogeneity substantially affects dynamic and static properties of the engine considered as an object of control since it leads to a lag of the acceleration time and to increase in fuel consumption. The summarized simulation results demonstrate that the foregoing properties of a jet engine are subject to considerable deterioration in pace with gradual increase of the assumed non-homogeneity of the temperature field. The simulations made it possible to find out that variations of the temperature field nonhomogeneity within the working agent at the turbine intake lead to huge fluctuation of the turbine rpm for the idle run.
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Yazar, Isil, Emre Kiyak, Fikret Caliskan, and T. Hikmet Karakoc. "Simulation-based dynamic model and speed controller design of a small-scale turbojet engine." Aircraft Engineering and Aerospace Technology 90, no. 2 (March 5, 2018): 351–58. http://dx.doi.org/10.1108/aeat-09-2016-0150.
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Purpose This paper aims to present a nonlinear mathematical model of a small-scale turbojet aeroengine and also a speed controller design that is conducted for the constructed nonlinear mathematical model. Design/methodology/approach In the nonlinear mathematical model of the turbojet engine, temperature, rotational speed, mass flow, pressure and other parameters are generated using thermodynamic equations (e.g. mass, energy and momentum conservation laws) and some algebraic equations. In calculation of the performance parameters, adaptive neuro fuzzy inference system (ANFIS) method is preferred in related components. All calculated values from the mathematical model are then compared with the cycle data of the turbojet engine. Because of the single variable control need and effect of noise factor, modified proportional–integral–derivative (PID) controller is treated for speed control. For whole operation envelope, various PID structures are designed individually, according to the operating points. These controller structures are then combined via gain-scheduling approach and integrated to the nonlinear engine model. Simulations are performed on MATLAB/Simulink environment for design and off-design operating points between idle to maximum thrust levels. Findings The cascade structure (proposed nonlinear engine aero-thermal model and speed controller) is simulated and tested at various operating points of the engine and for different transient conditions. Simulation results show that the transitions between the operating points are found successfully. Furthermore, the controller is effective for steady-state load changes. It is suggested to be used in real-time engine applications. Research limitations/implications Because of limited data, only speed control is treated and simulated. Practical implications It can be used as an application in the industry easily. Originality/value First point of novelty in the paper is in calculation of the performance parameters of compressor and turbine components. ANFIS method is preferred to predict performance parameters in related components. Second novelty in the paper can be seen in speed controller design part. Because of the single variable control need and effect of noise factor, modified PID is treated.
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Dhupal, D., B. Doloi, and B. Bhattacharyya. "Optimization of process parameters of Nd:YAG laser microgrooving of Al2TiO5 ceramic material by response surface methodology and artificial neural network algorithm." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 221, no. 8 (August 1, 2007): 1341–50. http://dx.doi.org/10.1243/09544054jem814.
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The high-intensity pulsed Nd:YAG laser has the capability to produce both deep grooves and microgrooves on a wide range of engineering materials such as ceramics, composites, and diamond. The micromachining of ceramics is highly demanded in industry because of its wide and potential uses in various fields such as automobile, electronic, aerospace, and biomedical engineering. Engineering ceramic, i.e. aluminium titanate (Al2TiO5), has tremendous application in the automobile and aero-engine industries owing to its excellent thermal properties. The present paper deals with the artificial neural network (ANN) and response surface methodology (RSM) based mathematical modelling and also an optimization analysis of the machining characteristics of the pulsed Nd:YAG laser during the microgrooving operation on Al2TiO5. The experiments were planned and carried out based on design of experiments (DOE). Lamp current, pulse frequency, pulse width, assist air pressure, and cutting speed were considered as machining process parameters during the pulsed Nd:YAG laser microgrooving operation and these parameters were also utilized to develop the ANN predictive model. The response criteria selected for optimization were upper width, lower width, and depth of the trapezoidal microgroove. The optimal process parameter settings were obtained as an assist air pressure of 1.2944 kgf/cm2, lamp current of 19.3070A, pulse frequency of 1.755 kHz, pulse width of 5.7087 per cent of duty cycle, and cutting speed of 10mm/s for achieving the desired upper width, lower width, and depth of the laser microgroove. The output of the RSM optimal data was validated through experimentation and the ANN predictive model. A good agreement is observed between the results based on the ANN predictive model and the actual experimental observations.
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Mazzei, Lorenzo, Antonio Andreini, and Bruno Facchini. "Assessment of modelling strategies for film cooling." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 5 (May 2, 2017): 1118–27. http://dx.doi.org/10.1108/hff-03-2016-0086.
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Purpose Effusion cooling represents one the most innovative techniques for the thermal management of aero-engine combustors liners. The huge amount of micro-perforations implies a significant computational cost if cooling holes are included in computational fluid dynamics (CFD) simulations; therefore, many efforts are reported in literature to develop lower-order approaches aiming at limiting the number of mesh elements. This paper aims to report a numerical investigation for validating two approaches for modelling film cooling, distinguished according to the way coolant is injected (i.e. through either point or distributed mass sources). Design/methodology/approach The approaches are validated against experimental data in terms of adiabatic effectiveness and heat transfer coefficient distributions obtained for effusion cooled flat plates. Additional reynolds-averaged naver stokes (RANS) simulations were performed meshing also the perforation, so as to distinguish the contribution of injection modelling with respect to intrinsic limitations of turbulence model modelling. Findings Despite the simplified strategies for coolant injection, this work clearly shows the feasibility of obtaining a sufficiently accurate reproduction of coolant protection in conjunction with a significant saving in terms of computational cost. Practical/implications The proposed methodologies allow to take into account the presence of film cooling in simulations of devices characterized by a huge number of holes. Originality/value This activity represents the first thorough and quantitative comparison between two approaches for film cooling modelling, highlighting the advantages involved in their application.
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Salvadori, Simone, Mauro Carnevale, Alessia Fanciulli, and Francesco Montomoli. "Uncertainty Quantification of Non-Dimensional Parameters for a Film Cooling Configuration in Supersonic Conditions." Fluids 4, no. 3 (August 10, 2019): 155. http://dx.doi.org/10.3390/fluids4030155.
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In transonic high-pressure turbine stages, oblique shocks originating from vane trailing edges impact the suction side of each adjacent vane. High-pressure vanes are cooled to tolerate the combustor exit-temperature levels, then it is highly probable that shock impingement will occur in proximity to a row of cooling holes. The presence of such a shock, together with the inevitable manufacturing deviations, alters the location of the shock impingement and of the performance parameters of each cooling hole. The present work provides a general description of the aero-thermal field that occurs on the rear suction side of a cooled vane. Computational Fluid Dynamics (CFD) is used to evaluate the deterministic response of the selected configurations in terms of adiabatic effectiveness, discharge coefficient, blowing ratio, density ratio, and momentum ratio. Turbulence is modelled by using both the Shear Stress Transport method (SST) and the Reynolds Stress Model (RSM) implemented in ANSYS ® FLUENT ® . The obtained results are compared with the experimental data obtained by the Institut für Thermische Strömungsmaschinen in Karlsruhe. Two uncertainty quantification methodologies based on Hermite polynomials and Padè–Legendre approximants are used to consider the probability distribution of the geometrical parameters and to evaluate the response surfaces for the system response quantities. Trailing-edge and cooling-hole diameters have been considered to be aleatory unknowns. Uncertainty quantification analysis allows for the assessment of the mutual effects on global and local parameters of the cooling device. Obtained results demonstrate that most of the parameters are independent by the variation of the aleatory unknowns while the standard deviation of the blowing ratio associated with the hole diameter uncertainty is around 12 % , with no impact by the trailing-edge thickness. No relevant advantages are found using either SST model or RSM in combination with Hermite polynomials and Padè–Legendre approximants.
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Shukla, Sidharth Kumar, and Amrita Priyadarshini. "Application of Machine Learning Techniques for Multi Objective Optimization of Response Variables in Wire Cut Electro Discharge Machining Operation." Materials Science Forum 969 (August 2019): 800–806. http://dx.doi.org/10.4028/www.scientific.net/msf.969.800.
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Wire Cut Electrical Discharge Machining (WEDM) is a non-conventional thermal machining process which is capable of accurately machine alloys having high hardness or part having complex shapes that are very difficult to be machined by the conventional machining processes. The WEDM finds applications in automobiles, aero–space, medical instruments, tool and die industries, etc. The input parameters considered for WEDM are pulse on time, pulse off time, flushing pressure, servo voltage, wire feed rate and wire tension. Performance of WEDM is mainly assessed by output variables such as, material removal rate (MRR), kerf width (Kw) and surface roughness (Ra) of the work piece being machined. Looking at the need of a suitable optimization model, the present work explores the feasibility of machine learning concepts to predict optimum surface roughness and kerf width simultaneously by making use of experimental data available in the literature for machining of Hastelloy C– 276 using WEDM. In most of the literatures, single objective optimization has been carried out for predicting optimum cutting parameters for WEDM. Hence, the present work presents a methodology that makes use of a machine learning algorithm namely, gradient descent method as an optimization technique to optimize both surface roughness and kerf width simultaneously (multi objective optimization) and compare the results with the existing literatures. It was observed that the input parameters such as pulse on time, pulse off time, and peak current have significant effect on both surface roughness and kerf width. The gradient descent method was successfully used for predicting the optimum values of response variables.
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Lopata, Stanislaw, Pawel Oclon, Tomasz Stelmach, and Pawel Markowski. "Heat transfer coefficient in elliptical tube at the constant heat flux." Thermal Science 23, Suppl. 4 (2019): 1323–32. http://dx.doi.org/10.2298/tsci19s4323l.
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Cross-flow heat exchangers with elliptical tubes are often used in industrial application. In comparison with round tubes, the elliptical tubes have a better aero-dynamic shape, which results in a lower pressure drop of working fluid flowing through the inter-tubular space of heat exchanger. Also, a higher heat flux is transferred from gas to the wall of such a tube due to the more intense heat exchange process. To prove this thesis, the values of the heat transfer coefficient from the wall of the elliptical pipe to the water flowing inside were determined, using the data from the conducted measurements. This study presents also research stand with a vertically positioned tube. In order to obtain a constant heat flux through the wall of elliptical tube, a resistance wire is used, evenly wound on the external surface of tube measuring section. The use of thermal insulation minimized heat loss to the environment to a negligible value. Installed K-type thermocouples allowed one to obtain, for various measurement conditions, the temperature distribution within the elliptical tube wall (for a given cross-section) and the water flowing inside it (in a given cross-section, at different depths, for both axes of the ellipse). The design of the stand allows such measurements in several locations along the length of the measurement section. The measurement results were used to verify numerical calculations. The relative error of the heat transfer coefficient value determined on the basis of CFD calculations using the SST-TR turbulence model in relation to the one determined on the basis of the measurement data is about 11%.
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Chereches, Tudor, Paul Lixandru, Sergiu Mazuru, Pavel Cosovschi, and Daniel Dragnea. "Numerical Simulation of Plastic Deformation Process of the Glass Mold Parts." Applied Mechanics and Materials 657 (October 2014): 126–31. http://dx.doi.org/10.4028/www.scientific.net/amm.657.126.
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In our present days numerical simulation became an important tool of engineering. Numerical simulation methods allow quantitative examination of the complex processes and phenomena in the general area of physics and also provide an insight in their dynamic evolution and even can become important tools for the discovery of new phenomena. In essence, the numerical simulation transfer important aspect of physical reality in discrete forms of mathematical description recreates and solves the problems on computer and finally, highlights issues that the analyst required. This modern numerical method approach, attacks the original problems in all their details on a much larger platform with a much smaller number of assumptions and approximations, in comparison to traditional methods. Transposition of the physics problems in the virtual space, governed by the force of computers, numerical simulation - as scientific approach - is becoming increasingly interesting for many fields of research. Basically, by means of numerical simulation are addressed fields such as mechanics deformable solids, fluid mechanics, aerodynamics, biomechanics, astrophysics. Numerical simulations follow a similar procedure to all the scientific approach, which consists in going through several stages, as follows: the phenomenon, the physical model, mathematical model, discrete model, and coding, numerical solution. In the plastic deformation of metals are involved, besides the mechanical properties and some thermal properties because even if the process is applied in the initial state to a cold material, along the process changes occur because of friction between materials and tools and transformation of plastic mechanical work into heat. Basic mechanical properties of the materials are underline through characteristic diagrams of materials obtained in simple tests of traction and compression. These tests were carried out in the Polytechnic University of Bucharest, Romanian Research & Development Institute for Gas Turbines COMOTI, Institute for Calculating and Testing Aero-Astronautic Structures STRAERO, SC UPS PILOT ARM Ltd, and Asachi Technical University of Iasi. To achieve the major objectives of the numerical simulation of the technological process of cold plastic deformation, are incorporated into the physical model three types of surfaces: cylindrical, conical and profiled. The sizes of the initial geometry were established in accordance with the basic dimensions of processed products by this method. For delimiting surfaces to be machined, the addition of grip (the tail) has a reduced diameter. Geometric models provide strength and rigidity needed for safely and accurately processing technology of cold plastic deformation. Geometric models and specimens which had been subjected to tensile tests, compression and hardness were made in the Glass Factory, Chisinau, Moldova.