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1
Flaszynski, Pawel, Michal Piotrowicz et Tommaso Bacci. « Clocking and Potential Effects in Combustor–Turbine Stator Interactions ». Aerospace 8, no 10 (2 octobre 2021) : 285. http://dx.doi.org/10.3390/aerospace8100285.
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Investigations of combustors and turbines separately have been carried out for years by research institutes and aircraft engine companies, but there are still many questions about the interaction effect. In this paper, a prediction of a turbine stator’s potential effect on flow in a combustor and the clocking effect on temperature distribution in a nozzle guide vane are discussed. Numerical simulation results for the combustor simulator and the nozzle guide vane (NGV) of the first turbine stage are presented. The geometry and flow conditions were defined according to measurements carried out on a test section within the framework of the EU FACTOR (full aerothermal combustor–turbine interactions research) project. The numerical model was validated by a comparison of results against experimental data in the plane at a combustor outlet. Two turbulence models were employed: the Spalart–Allmaras and Explicit Algebraic Reynolds Stress models. It was shown that the NGV potential effect on flow distribution at the combustor–turbine interface located at 42.5% of the axial chord is weak. The clocking effect due to the azimuthal position of guide vanes downstream of the swirlers strongly affects the temperature and flow conditions in a stator cascade.
2
Karki, K. C., V. L. Oechsle et H. C. Mongia. « A Computational Procedure for Diffuser-Combustor Flow Interaction Analysis ». Journal of Engineering for Gas Turbines and Power 114, no 1 (1 janvier 1992) : 1–7. http://dx.doi.org/10.1115/1.2906301.
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This paper describes a diffuser-combustor flow interaction analysis procedure for gas turbine combustion systems. The method is based on the solution of the Navier–Stokes equations in a generalized nonorthogonal coordinate system. The turbulence effects are modeled via the standard two-equation (k-ε) model. The method has been applied to a practical gas turbine combustor-diffuser system that includes support struts and fuel nozzles. Results have been presented for a three-dimensional simulation, as well as for a simplified axisymmetric simulation. The flow exhibits significant three-dimensional behavior. The axisymmetric simulation is shown to predict the static pressure recovery and the total pressure losses reasonably well.
3
Isvoranu, Dragos D., et Paul G. A. Cizmas. « Numerical Simulation of Combustion and Rotor-Stator Interaction in a Turbine Combustor ». International Journal of Rotating Machinery 9, no 5 (2003) : 363–74. http://dx.doi.org/10.1155/s1023621x03000344.
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This article presents the development of a numerical algorithm for the computation of flow and combustion in a turbine combustor. The flow and combustion are modeled by the Reynolds-averaged Navier-Stokes equations coupled with the species-conservation equations. The chemistry model used herein is a two-step, global, finite-rate combustion model for methane and combustion gases. The governing equations are written in the strong conservation form and solved using a fully implicit, finite-difference approximation. The gas dynamics and chemistry equations are fully decoupled. A correction technique has been developed to enforce the conservation of mass fractions. The numerical algorithm developed herein has been used to investigate the flow and combustion in a one-stage turbine combustor.
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Muirhead, Kirsten, et Stephen Lynch. « Computational Study of Combustor Dilution Flow Interaction with Turbine Vanes ». Journal of Propulsion and Power 35, no 1 (janvier 2019) : 54–71. http://dx.doi.org/10.2514/1.b36912.
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Cameron, C. D., J. Brouwer, C. P. Wood et G. S. Samuelsen. « A Detailed Characterization of the Velocity and Thermal Fields in a Model Can Combustor With Wall Jet Injection ». Journal of Engineering for Gas Turbines and Power 111, no 1 (1 janvier 1989) : 31–35. http://dx.doi.org/10.1115/1.3240224.
Texte intégralRésumé :
This work represents a first step in the establishment of a data base to study the interaction and influence of liquid fuel injection, wall jet interaction, and dome geometry on the fuel air mixing process in a flowfield representative of a practical combustor. In particular, the aerodynamic and thermal fields of a model gas turbine combustor are characterized via detailed spatial maps of velocity and temperature. Measurements are performed at an overall equivalence ratio of 0.3 with a petroleum JP-4 fuel. The results reveal that the flowfield characteristics are significantly altered in the presence of reaction. Strong on-axis backmixing in the dome region, present in the isothermal flow, is dissipated in the case of reaction. The thermal field exhibits the primary, secondary, and dilution zone progression of temperatures characteristic of practical gas turbine combustors. A parametric variation on atomizing air reveals a substantial sensitivity of the mixing in this flow to nozzle performance and spray symmetry.
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Farisco, Federica, Lukasz Panek et Jim BW Kok. « Thermo-acoustic cross-talk between cans in a can-annular combustor ». International Journal of Spray and Combustion Dynamics 9, no 4 (2 juillet 2017) : 452–69. http://dx.doi.org/10.1177/1756827717716373.
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Thermo-acoustic instabilities in gas turbine engines are studied to avoid engine failure. Compared to the engines with annular combustors, the can-annular combustor design should be less vulnerable to acoustic burner-to-burner interaction, since the burners are acoustically coupled only by the turbine stator stage and the plenum. However, non-negligible cross-talk between neighboring cans has been observed in measurements in such machines. This study is focused on the analysis of the acoustic interaction between the cans. Simplified two-dimensional (2D) and three-dimensional (3D) equivalent systems representing the corresponding engine alike turbine design are investigated. Thermo-acoustic instabilities are reproduced using a forced response approach. Compressible large eddy simulation based on the open source computational fluid dynamics OpenFOAM framework is used applying accurate boundary conditions for the flow and the acoustics. A study of the reflection coefficient and of the transfer function between the cans has been performed. Comparisons between 2D and 3D equivalent configurations have been evaluated.
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Azwadi, Nor, et Ehsan Kianpour. « The Effect of Blowing Ratio on Film Cooling Effectiveness Using Cylindrical and Row Trenched Cooling Holes with Alignment Angle of 90 Degrees ». Mathematical Problems in Engineering 2014 (2014) : 1–9. http://dx.doi.org/10.1155/2014/470576.
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This paper presents the effects of blowing ratio on film cooling performance adjacent to the combustor endwall using cylindrical and row trenched cooling holes with alignment angle of 90 degrees. A three-dimensional representation of a Pratt and Whitney gas turbine engine was simulated and analysed using a commercial finite volume package FLUENT 6.2.26. The combustor simulator was designed to combine the interaction of two rows of dilution jets, which were staggered in the streamwise direction and aligned in the spanwise direction. As a result, the combustor with row trenched holes gave almost doubled cooling performance compared to the baseline case. In addition, the film cooling layer was increased at high blowing ratio, and thus it enhanced the cooling performance.
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Isvoranu, Dragos D., et Paul G. A. Cizmas. « Numerical Simulation of Combustion and Rotor-Stator Interaction in a Turbine Combustor ». International Journal of Rotating Machinery 9, no 5 (1 septembre 2003) : 363–74. http://dx.doi.org/10.1080/10236210309498.
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Stöhr, Michael, Isaac Boxx, Campbell D. Carter et Wolfgang Meier. « Experimental study of vortex-flame interaction in a gas turbine model combustor ». Combustion and Flame 159, no 8 (août 2012) : 2636–49. http://dx.doi.org/10.1016/j.combustflame.2012.03.020.
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Serbin, Sergey. « THERMO ACOUSTIC PROCESSES IN LOW EMISSION COMBUSTION CHAMBER OF GAS TURBINE ENGINE CAPACITY 25 MW ». Science Journal Innovation Technologies Transfer, no 2019-2 (5 mai 2019) : 86–90. http://dx.doi.org/10.36381/iamsti.2.2019.86-90.
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The appliance of modern tools of the computational fluid dynamics for the investigation of the pulsation processes in the combustion chamber caused by the design features of flame tubes and aerodynamic interaction compressor, combustor and turbine is discussed. The aim of the research is to investigate and forecast the non-stationary processes in the gas turbine combustion chambers. The results of the numerical experiments which were carried out using three-dimensional mathematical models in gaseous fuels combustion chambers reflect sufficiently the physical and chemical processes of the unsteady combustion and can be recommended to optimize the geometrical and operational parameters of the low-emission combustion chamber. The appliance of such mathematical models are reasonable for the development of new samples of combustors which operate at the lean air-fuel mixture as well as for the modernization of the existing chambers with the aim to develop the constructive measures aimed at reducing the probability of the occurrence of the pulsation combustion modes. Keywords: gas turbine engine, combustor, turbulent combustion, pulsation combustion, numerical methods, mathematical simulation.
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Fureby, C. « Large eddy simulation modelling of combustion for propulsion applications ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 367, no 1899 (28 juillet 2009) : 2957–69. http://dx.doi.org/10.1098/rsta.2008.0271.
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Predictive modelling of turbulent combustion is important for the development of air-breathing engines, internal combustion engines, furnaces and for power generation. Significant advances in modelling non-reactive turbulent flows are now possible with the development of large eddy simulation (LES), in which the large energetic scales of the flow are resolved on the grid while modelling the effects of the small scales. Here, we discuss the use of combustion LES in predictive modelling of propulsion applications such as gas turbine, ramjet and scramjet engines. The LES models used are described in some detail and are validated against laboratory data—of which results from two cases are presented. These validated LES models are then applied to an annular multi-burner gas turbine combustor and a simplified scramjet combustor, for which some additional experimental data are available. For these cases, good agreement with the available reference data is obtained, and the LES predictions are used to elucidate the flow physics in such devices to further enhance our knowledge of these propulsion systems. Particular attention is focused on the influence of the combustion chemistry, turbulence–chemistry interaction, self-ignition, flame holding burner-to-burner interactions and combustion oscillations.
12
Tsao, J. M., et C. A. Lin. « Reynolds stress modelling of jet and swirl interaction inside a gas turbine combustor ». International Journal for Numerical Methods in Fluids 29, no 4 (28 février 1999) : 451–64. http://dx.doi.org/10.1002/(sici)1097-0363(19990228)29:4<451 ::aid-fld796>3.0.co;2-x.
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Wakabayashi, T., S. Ito, S. Koga, M. Ippommatsu, K. Moriya, K. Shimodaira, Y. Kurosawa et K. Suzuki. « Performance of a Dry Low-NOx Gas Turbine Combustor Designed With a New Fuel Supply Concept ». Journal of Engineering for Gas Turbines and Power 124, no 4 (24 septembre 2002) : 771–75. http://dx.doi.org/10.1115/1.1473154.
Texte intégralRésumé :
This paper describes the performance of a dry low-NOx gas turbine combustor designed with a new fuel supply concept. This concept uses automatic fuel distribution achieved by an interaction between the fuel jet and the airflow. At high loads, most of the fuel is supplied to the lean premixed combustion region for low-NOx, while at low loads, it is supplied to the pilot combustion region for stable combustion. A numerical simulation was carried out to estimate the equivalence ratio in the fuel supply unit. Next, through the pressurized combustion experiments on the combustor with this fuel supply unit using natural gas as fuel, it was confirmed that NOx emissions were reduced and stable combustion was achieved over a wide equivalence ratio range.
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McGuirk, J. J., et J. M. L. M. Palma. « Experimental Investigation of the Flow Inside a Water Model of a Gas Turbine Combustor : Part 1—Mean and Turbulent Flowfield ». Journal of Fluids Engineering 117, no 3 (1 septembre 1995) : 450–58. http://dx.doi.org/10.1115/1.2817283.
Texte intégralRésumé :
The present study examines the flow inside the water model of a gas turbine combustor, with the two main objectives of increasing the understanding of this type of flow and providing experimental data to assist the development of mathematical models. The main features of the geometry are the interaction between two rows of radially opposed jets penetrating a cross-flowing axial stream with and without swirl, providing a set of data of relevance to all flows containing these features. The results, obtained by laser Doppler velocimetry, showed that under the present flow conditions, the first row of jets penetrate almost radially into the combustor and split after impingement, giving rise to a region of high turbulence intensity and a toroidal recirculation zone in the head of the combustor. Part 1 discusses the mean and turbulent flowfield, and the detailed study of the region near the impingement of the first row of jets is presented in Part 2 of this paper.
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Sharma, Debojit, Subrat Garnayak, Aditya Bandopadhyay, S. K. Dash et Mahendra Reddy Vanteru. « Influence of jet velocity and heat recuperation on the flame stabilization in a non-premixed mesoscale combustor : An exergetic approach ». Physics of Fluids 35, no 2 (février 2023) : 025110. http://dx.doi.org/10.1063/5.0137382.
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An experimental and numerical model to determine the exergy balance based on flow availability and availability transfer in the process of liquefied petroleum gas (LPG)/air combustion in mesoscale gas turbine combustor is developed to elucidate the second law efficiency and total thermodynamic irreversibility. In terms of developing an energy and exergy-efficient combustor design, the present work highlights the influence of vortex shedding and recirculation in the volumetric entropy production and the exergy efficiency. It is performed in a heat recuperative high-intensity LPG-fueled mesoscale combustor for mini-gas turbine applications. The combustor is operated at different thermal inputs ranging from 0.2 to 1.0 kW under range of equivalence ratios of ϕ = 0.4–1.23. The Favre-averaged governing equations are solved by using finite volume-based approach. The standard k–ε turbulence model with modified empirical constant, [Formula: see text], is considered to model the turbulence quantities. The volumetric reaction-based eddy-dissipation concept model and a reduced skeletal model (50 species and 373 reactions) are used for turbulence–chemistry interaction. The design methodology, total volumetric entropy generation, destructive exergy due to thermodynamic irreversibility, exergy efficiency, flow recirculation, and mixing characteristics (reacting and non-reacting) are reported. The entropy generation rate due to thermal conduction is approximately 50% of the total entropy generation, while its contribution percentage due to chemical reaction is the smallest. The exergy efficiency reaches its peak with [Formula: see text] = 79.41% at 1.0 kW under fuel-rich condition, while its minimum value of 41.49% is obtained at 0.2 kW under fuel-lean (ϕ = 0.8) condition.
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Ehsan, Kianpour, et Nor Azwadi Che Sidik. « Analyzes of Film Cooling from Cylindrical and Row Trenched Holes with Alignment Angle of 90 Degrees at Low Blowing Ratio ». Applied Mechanics and Materials 695 (novembre 2014) : 376–79. http://dx.doi.org/10.4028/www.scientific.net/amm.695.376.
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The current study was conducted to analyze the effects of cylindrical and row trenched cooling holes with alignment angle of 90 degrees at blowing ratio, BR = 1.25 on the film cooling effectiveness near the end wall surface of a combustor simulator. In the current research a three dimensional representation of Pratt and Whitney gas turbine engine was simulated and analyzed with a commercial finite volume package FLUENT 6.2.26. This study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passages. This combustor simulator combined the interaction of two rows of dilution jets, which were staggered in the stream wise direction and aligned in the span wise arrangement, with that of film cooling along the combustor liner walls. The findings of the study declared that with using the row trenched holes near the end wall surface, film cooling effectiveness is increased three times compared to the cooling performance of baseline case.
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Che Sidik, Nor Azwadi, et Kianpour Ehsan. « Computational Investigation of Film Cooling from Cylindrical and Row Trenched Cooling Holes near the Combustor End Wall ». Applied Mechanics and Materials 554 (juin 2014) : 225–29. http://dx.doi.org/10.4028/www.scientific.net/amm.554.225.
Texte intégralRésumé :
This study was accomplished in order to investigate the effects of cylindrical and row trenched cooling holes with alignment angle of 0 degree and 90 degree at blowing ratio, BR = 3.18 on the film cooling performance adjacent to the endwall surface of a combustor simulator. In this research a three dimensional representation of Pratt and Whitney gas turbine engine was simulated and analyzed with a commercial finite volume package FLUENT 6.2. The current study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passages. This combustor simulator combined the interaction of two rows of dilution jets, which were staggered in the stream wise direction and aligned in the span wise direction, with that of film cooling along the combustor liner walls. The findings of the study declared that with using the row trenched holes near the endwall surface, film cooling effectiveness is doubled compared to the cooling performance of baseline case.
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Sattelmayer, T., M. P. Felchlin, J. Haumann, J. Hellat et D. Styner. « Second-Generation Low-Emission Combustors for ABB Gas Turbines : Burner Development and Tests at Atmospheric Pressure ». Journal of Engineering for Gas Turbines and Power 114, no 1 (1 janvier 1992) : 118–25. http://dx.doi.org/10.1115/1.2906293.
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Based on fundamental research concerning swirling flows, including the vortex breakdown phenomenon, as well as on stability considerations of premixed flames, a second generation of low-emission burners has been developed. The lean premixing technique provides NOx emissions below 25 ppmv for natural gas. For liquid fuels the oxides of nitrogen are limited to 42 ppmv (oil No. 2). The novel burner technology will be applied to the well-known ABB silo combustor. As a first step the Conical Premix Burner will be used to retrofit the ABB type 11N. For the ABB gas turbine type 8 the design of a novel fully annular combustor is in progress. Most of the conceptual work concerning burner aerodynamics and burner-burner interaction has been carried out on scaled-down burner and combustor models. For a second step a sector of the combustor in 1:1 scale has been tested at atmospheric pressure. Additional high-pressure tests provide information about the combustor performance at engine conditions. The present paper summarizes the results of the first two steps beginning with the early ideas in the conceptual phase up to the 1:1 tests, which prove the low-NOx capability for both gaseous and liquid fuels under atmospheric pressure conditions.
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Stöhr, M., C. M. Arndt et W. Meier. « Effects of Damköhler number on vortex–flame interaction in a gas turbine model combustor ». Proceedings of the Combustion Institute 34, no 2 (janvier 2013) : 3107–15. http://dx.doi.org/10.1016/j.proci.2012.06.086.
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Danaila, Sterian, Dragoș Isvoranu et Constantin Leventiu. « Preliminary Simulation of a 3D Turbine Stage with In Situ Combustion ». Applied Mechanics and Materials 772 (juillet 2015) : 103–7. http://dx.doi.org/10.4028/www.scientific.net/amm.772.103.
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This paper presents the preliminary results of the numerical simulation of flow and combustion in a one stage turbine combustor (turbine stage in situ combustion). The main purpose of the simulation is to assess the stability of the in situ combustion with respect to the unsteadiness induced by the rotor-stator interaction. Apart from previous attempts, the salient feature of this CFD approach is the new fuel injection concept that consisting of a perforated pipe placed at mid-pitch in the stator row passage. The flow and combustion are modelled by the Reynolds-averaged Navier-Stokes equations coupled with the species transport equations. The chemistry model used herein is a two-step, global, finite rate combustion model while the turbulence model is the shear stress transport model. The chemistry turbulence interaction is described in terms of eddy dissipation concept.
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Pinelli, Lorenzo, Leonardo Lilli, Andrea Arnone, Paolo Gaetani et Giacomo Persico. « Numerical Study of Entropy Wave Evolution within a HPT Stage ». E3S Web of Conferences 197 (2020) : 11011. http://dx.doi.org/10.1051/e3sconf/202019711011.
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Component reciprocal interaction and aero-thermal coupling are critical aspects in modern turbomachinery design. Combustors and highpressure turbine (HPT) interaction is extremely critical due to the compact and lightweight system design. In this context, computational and experimental analyses are thus necessary to study the interaction of the high temperature gas coming from combustor systems and entering the turbine in order to avoid engine mis-operations and to lower the indirect core noise generation. This paper presents a numerical study of pulsating temperature distortion (entropy wave) evolution within a high pressure turbine stage. Four different clocking positions between the 11 temperature spots and the 22 stators have been studied. The numerical results, obtained by URANS computations (TRAF code) and by a dedicated post-processing based on Fourier coefficients, have been compared with experimental measurements coming from the Laboratorio di Fluidodinamica delle Macchine (LFM) of the Politecnico di Milano (Italy) where the HP stage rig is located. The excellent agreement between numerical results and experimental acquisitions confirms the accuracy of the numerical approach. Such results also suggest recommendations for the thermal design of the rows and are the main prerequisite for the study of the indirect core noise generation.
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Nor Azwadi Che Sidik et Ehsan Kianpour. « Influence of Compound Spherical Trenched Holes on Film Cooling Performance at the end of Combustor Simulator ». Journal of Advanced Research in Applied Sciences and Engineering Technology 28, no 1 (11 septembre 2022) : 13–24. http://dx.doi.org/10.37934/araset.28.1.1324.
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The major effects of cylindrical and spherical trenched cooling holes with distance between the hole surface and the combustion chamber panel and the filler diameter on the spherical hole contact surface and the panel surface H=0.3,R=D/2=0.1, H=0.3, R=D/2=0.2 and H=0.3, R=D/2=0.3 cm at BR=3.18 on the film cooling effectiveness near the combustor end wall surface is an important subject to study in details. In this research, a three-dimensional representation of a Pratt and Whitney gas turbine engine was simulated and analysed with a commercial finite volume package FLUENT 6.2.26. The analyses were done with RANS turbulence model on internal cooling passages. The combustor simulator was combined with the interaction of two rows of dilution jets, which were staggered in the streamwise direction and aligned in the spanwise direction. In comparison with the baseline case, the application of trenched holes increased the effectiveness of film cooling up to 47% near the wall surface and an average of 35% in depth of combustor simulator .
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Kru¨ger, U., J. Hu¨ren, S. Hoffmann, W. Krebs, P. Flohr et D. Bohn. « Prediction and Measurement of Thermoacoustic Improvements in Gas Turbines With Annular Combustion Systems ». Journal of Engineering for Gas Turbines and Power 123, no 3 (1 octobre 2000) : 557–66. http://dx.doi.org/10.1115/1.1374437.
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Environmental compatibility requires low emission burners for gas turbine power plants. In the past, significant progress has been made developing low NOx and CO burners by introducing lean premixed techniques in combination with annular combustion chambers. Unfortunately, these burners often have a more pronounced tendency to produce combustion-driven oscillations than conventional burner designs. The oscillations may be excited to such an extent that the risk of engine failure occurs. For this reason, the prediction of these thermoacoustic instabilities in the design phase of an engine becomes more and more important. A method based on linear acoustic four-pole elements has been developed to predict instabilities of the ring combustor of the 3A-series gas turbines. The complex network includes the whole combustion system starting from both compressor outlet and fuel supply system and ending at the turbine inlet. The flame frequency response was determined by a transient numerical simulation (step-function approach). Based on this method, possible improvements for the gas turbine are evaluated in this paper. First, the burner impedance is predicted theoretically and compared with results from measurements on a test rig for validation of the prediction approach. Next, the burner impedance in a gas turbine combustion system is analyzed and improved thermoacoustically. Stability analyses for the gas turbine combustion system show the positive impact of this improvement. Second, the interaction of the acoustic parts of the gas turbine system has been detuned systematically in circumferential direction of the annular combustion chamber in order to find a more stable configuration. Stability analyses show the positive effect of this measure as well. The results predicted are compared with measurements from engine operation. The comparisons of prediction and measurements show the applicability of the prediction method in order to evaluate the thermoacoustic stability of the combustor as well as to define possible countermeasures.
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Kianpour, Ehsan, et Nor Azwadi Che Sidik. « A Detailed Study of Row-Trenched Holes at the Combustor Exit on Film-Cooling Effectiveness ». Mechanics and Mechanical Engineering 23, no 1 (10 juillet 2019) : 246–52. http://dx.doi.org/10.2478/mme-2019-0033.
Texte intégralRésumé :
Abstract To analyse the effects of cylindrical- and row-trenched cooling holes with an alignment angle of 90 degrees on the film-cooling effectiveness near the combustor end wall surface at a blowing ratio of 3.18, the current research was done. This research included a 3D representation of a Pratt and Whitney gas turbine engine, which was simulated and analysed with a commercial finite volume package FLUENT 6.2.26. The analysis was done with Reynolds-averaged Navier–Stokes turbulence model on internal cooling passages. This combustor simulator was combined with the interaction of two rows of dilution jets, which were staggered in the streamwise direction and aligned in the spanwise direction. In comparison with the baseline case of cooling holes, using row-trenched hole near the end wall surface increased the film-cooling effectiveness 44% in average.
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Marudhappan, Raja, Chandrasekhar Udayagiri et Koni Hemachandra Reddy. « Combustion chamber design and reaction modeling for aero turbo-shaft engine ». Aircraft Engineering and Aerospace Technology 91, no 1 (7 janvier 2018) : 94–111. http://dx.doi.org/10.1108/aeat-10-2017-0217.
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Purpose The purpose of this paper is to formulate a structured approach to design an annular diffusion flame combustion chamber for use in the development of a 1,400 kW range aero turbo shaft engine. The purpose is extended to perform numerical combustion modeling by solving transient Favre Averaged Navier Stokes equations using realizable two equation k-e turbulence model and Discrete Ordinate radiation model. The presumed shape β-Probability Density Function (β-PDF) is used for turbulence chemistry interaction. The experiments are conducted on the real engine to validate the combustion chamber performance. Design/methodology/approach The combustor geometry is designed using the reference area method and semi-empirical correlations. The three dimensional combustor model is made using a commercial software. The numerical modeling of the combustion process is performed by following Eulerian approach. The functional testing of combustor was conducted to evaluate the performance. Findings The results obtained by the numerical modeling provide a detailed understanding of the combustor internal flow dynamics. The transient flame structures and streamline plots are presented. The velocity profiles obtained at different locations along the combustor by numerical modeling mostly go in-line with the previously published research works. The combustor exit temperature obtained by numerical modeling and experiment are found to be within the acceptable limit. These results form the basis of understanding the design procedure and opens-up avenues for further developments. Research limitations/implications Internal flow and combustion dynamics obtained from numerical simulation are not experimented owing to non-availability of adequate research facilities. Practical implications This study contributes toward the understanding of basic procedures and firsthand experience in the design aspects of combustors for aero-engine applications. This work also highlights one of the efficient, faster and economical aero gas turbine annular diffusion flame combustion chamber design and development. Originality/value The main novelty in this work is the incorporation of scoops in the dilution zone of the numerical model of combustion chamber to augment the effectiveness of cooling of combustion products to obtain the desired combustor exit temperature. The use of polyhedral cells for computational domain discretization in combustion modeling for aero engine application helps in achieving faster convergence and reliable predictions. The methodology and procedures presented in this work provide a basic understanding of the design aspects to the beginners working in the gas turbine combustors particularly meant for turbo shaft engines applications.
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Giezendanner, R., P. Weigand, X. R. Duan, W. Meier, U. Meier, M. Aigner et B. Lehmann. « Laser-Based Investigations of Periodic Combustion Instabilities in a Gas Turbine Model Combustor ». Journal of Engineering for Gas Turbines and Power 127, no 3 (24 juin 2005) : 492–96. http://dx.doi.org/10.1115/1.1850498.
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The driving mechanism of pulsations in gas turbine combustors depends on a complex interaction between flow field, chemistry, heat release, and acoustics. Experimental data on all these factors are therefore required to obtain insight into the coupling mechanisms during a pulsation period. In order to develop a comprehensive experimental database to support a phenomenological understanding and to provide validation data for numerical simulation, a standard burner for optical investigations was established that exhibits strong self-excited oscillations. The burner was a swirl-stabilized nonpremixed model combustor designed for gas turbine applications and operated using methane as fuel at atmospheric pressure. It was mounted in a combustion chamber, which provides almost unobstructed optical access. The periodic combustion instabilities were studied by a variety of phase-resolved laser-based diagnostic techniques, locked to the frequency of the dominant pressure oscillation. Measurement techniques used were LDV for velocity measurements, planar laser-induced fluorescence for imaging of CH and OH radicals, and laser Raman scattering for the determination of the major species concentrations, temperature, and mixture fraction. The phase-resolved measurements revealed significant variations of all measured quantities in the vicinity of the nozzle exit, which trailed off quickly with increasing distance. A strong correlation of the heat release rate and axial velocity at the nozzle was observed, while the mean mixture fraction as well as the temperature in the periphery of the flame is phase shifted with respect to axial velocity oscillations. A qualitative interpretation of the experimental observations is given, which will help to form a better understanding of the interaction between flow field, mixing, heat release, and temperature in pulsating reacting flows, particularly when accompanied by corresponding CFD simulations that are currently underway.
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Benim, Ali Cemal, Sohail Iqbal, Franz Joos et Alexander Wiedermann. « Numerical Analysis of Turbulent Combustion in a Model Swirl Gas Turbine Combustor ». Journal of Combustion 2016 (2016) : 1–12. http://dx.doi.org/10.1155/2016/2572035.
Texte intégralRésumé :
Turbulent reacting flows in a generic swirl gas turbine combustor are investigated numerically. Turbulence is modelled by a URANS formulation in combination with the SST turbulence model, as the basic modelling approach. For comparison, URANS is applied also in combination with the RSM turbulence model to one of the investigated cases. For this case, LES is also used for turbulence modelling. For modelling turbulence-chemistry interaction, a laminar flamelet model is used, which is based on the mixture fraction and the reaction progress variable. This model is implemented in the open source CFD code OpenFOAM, which has been used as the basis for the present investigation. For validation purposes, predictions are compared with the measurements for a natural gas flame with external flue gas recirculation. A good agreement with the experimental data is observed. Subsequently, the numerical study is extended to syngas, for comparing its combustion behavior with that of natural gas. Here, the analysis is carried out for cases without external flue gas recirculation. The computational model is observed to provide a fair prediction of the experimental data and predict the increased flashback propensity of syngas.
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Schildmacher, K. U., et R. Koch. « Experimental Investigation of the Interaction of Unsteady Flow With Combustion ». Journal of Engineering for Gas Turbines and Power 127, no 2 (1 avril 2005) : 295–300. http://dx.doi.org/10.1115/1.1789512.
Texte intégralRésumé :
In order to reduce the dimensions of the combustor, swirl stabilized flames are used in heavy duty gas turbines. In our recent investigation of the swirling flow at a single heavy duty gas turbine burner under nonreacting conditions typical instabilities like precessing vortex cores and vortex shedding have been found (Schildmacher et al., Proceedings of the 6th European Conference on Industrial Furnaces and Boilers). In the present paper the experimental investigations will be discussed. Combustion instabilities have been analyzed by phase-locked laser doppler anemometer measurements. For the reacting flow, also combustion instabilities could be detected. The amplitude increases strongly with the equivalence ratio. The frequency of the oscillations for reacting conditions has been found to be slightly shifted towards lower frequencies compared to those of the corresponding nonreacting flow. In addition, for the reacting flow a linear and nonlinear range of oscillations could be discriminated.
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Gruhlke, Pascal, Christian Beck, Bertram Janus et Andreas M. Kempf. « LES Analysis of CO Emissions from a High Pressure Siemens Gas Turbine Prototype Combustor at Part Load ». Energies 13, no 21 (3 novembre 2020) : 5751. http://dx.doi.org/10.3390/en13215751.
Texte intégralRésumé :
This work contributes to the understanding of mechanisms that lead to increased carbon monoxide (CO) concentrations in gas turbine combustion systems. Large-eddy simulations (LES) of a full scale high pressure prototype Siemens gas turbine combustor at three staged part load operating conditions are presented, demonstrating the ability to predict carbon monoxide pollutants from a complex technical system by investigating sources of incomplete CO oxidation. Analytically reduced chemistry is applied for the accurate pollutant prediction together with the dynamic thickened flame model. LES results show that carbon monoxide emissions at the probe location are predicted in good agreement with the available test data, indicating two operating points with moderate pollutant levels and one operating point with CO concentrations below 10 ppm. Large mixture inhomogeneities are identified in the combustion chamber for all operating points. The investigation of mixture formation indicates that fuel-rich mixtures mainly emerge from the pilot stage resulting in high equivalence ratio streaks that lead to large CO levels at the combustor outlet. Flame quenching due to flame-wall-interaction are found to be of no relevance for CO in the investigated combustion chamber. Post-processing with Lagrangian tracer particles shows that cold air—from effusion cooling or stages that are not being supplied with fuel—lead to significant flame quenching, as mixtures are shifted to leaner equivalence ratios and the oxidation of CO is inhibited.
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Ahmed, E., et Y. Huang. « Flame volume prediction and validation for lean blow-out of gas turbine combustor ». Aeronautical Journal 121, no 1236 (12 janvier 2017) : 237–62. http://dx.doi.org/10.1017/aer.2016.125.
Texte intégralRésumé :
ABSTRACTLean Blow-Out (LBO) limits are critically important in the operation of aero engines. Previously, Lefebvre's LBO empirical correlation has been extended to the flame volume concept by the authors. Flame volume takes into account the effects of geometric configuration, spatial interaction of mixing jets, turbulence, heat transfer and combustion processes inside the gas turbine combustion chamber. For these reasons, LBO predictions based on flame volume are more accurate. Although LBO prediction accuracy has improved, it poses a challenge associated with Vfestimation in real gas turbine combustors. This work extends the approach of flame volume prediction based on fuel iterative approximation with cold flow simulations to reactive flow simulations. Flame volume for 11 combustor configurations were simulated and validated against experimental data. To make prediction methodology robust, as required in preliminary design stage, reactive flow simulations were carried out with the combination of presumed Probability Density Function (PDF) and discrete phase model (DPM) in Fluent 15.0 The criterion for flame identification was defined. Two important parameters—critical injection diameter (Dp,crit) and critical temperature (Tcrit)—were identified and their influence on reactive flow simulation was studied for Vfestimation. Results exhibit ±15% error in Vf estimation with experimental data.
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CHA, DONG-JIN. « COMBUSTION INSTABILITY ANALYSIS OF A MODEL GAS TURBINE COMBUSTOR WITH CLOSED ACOUSTIC BOUNDARIES AT BOTH ENDS ». International Journal of Air-Conditioning and Refrigeration 19, no 03 (septembre 2011) : 231–38. http://dx.doi.org/10.1142/s2010132511000569.
Texte intégralRésumé :
Combustion instability is a major issue in designing gas turbine combustors for an efficient operation with low emissions. Combustion instability is induced by the interaction of the unsteady heat release of the combustion process and changes in the acoustic pressure in the combustion chamber. In an effort to develop a technique to predict self-excited combustion instability of gas turbine combustors, a new stability analysis method based on the transfer matrix method was developed. The method views the combustion system as a one-dimensional acoustic system with a side branch and describes the heat source as the input to the system. This approach makes it possible to use not only the advantages of the transfer matrix method but also well established classic control theories. The approach is applied to a gas turbine combustion system, which shows the validity and effectiveness of the approach.
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Koutmos, P., et J. J. McGuirk. « Investigation of Swirler/Dilution Jet Flow Split on Primary Zone Flow Patterns in a Water Model Can-Type Combustor ». Journal of Engineering for Gas Turbines and Power 111, no 2 (1 avril 1989) : 310–17. http://dx.doi.org/10.1115/1.3240253.
Texte intégralRésumé :
LDA measurements of the three mean velocity components and the corresponding turbulence intensities have been made to provide qualitative and quantitative information on the flow field in a water model of a can-type gas turbine combustion chamber. The combustor geometry comprised a swirl-driven primary zone, annulus-fed rows of primary and secondary jets, and an exit contraction. The effect of variation of the flow split between the swirler and the dilution holes on the flow pattern in the primary zone has been investigated in detail. Flow visualization studies revealed that significant changes occur in this region due to the interaction between the swirling flow and the radially directed primary jets. A large toroidal recirculation was formed and high levels of turbulence energy were generated in the core of the combustor at low levels of swirler flow rate. As the swirl level increases, the strength of this recirculation was observed to weaken. Beyond a critical level, the primary recirculation was pushed off center and the undesirable feature of a forward velocity on the combustor axis in the primary zone was observed. Despite the dramatic changes brought about in the primary zone, the flow pattern downstream of the secondary jets was practically the same for all flow splits due to the strong mixing caused by the two rows of jets.
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Colban, W., K. A. Thole et M. Haendler. « Experimental and Computational Comparisons of Fan-Shaped Film Cooling on a Turbine Vane Surface ». Journal of Turbomachinery 129, no 1 (29 janvier 2006) : 23–31. http://dx.doi.org/10.1115/1.2370747.
Texte intégralRésumé :
The flow exiting the combustor in a gas turbine engine is considerably hotter than the melting temperature of the turbine section components, of which the turbine nozzle guide vanes see the hottest gas temperatures. One method used to cool the vanes is to use rows of film-cooling holes to inject bleed air that is lower in temperature through an array of discrete holes onto the vane surface. The purpose of this study was to evaluate the row-by-row interaction of fan-shaped holes as compared to the performance of a single row of fan-shaped holes in the same locations. This study presents adiabatic film-cooling effectiveness measurements from a scaled-up, two-passage vane cascade. High-resolution film-cooling measurements were made with an infrared camera at a number of engine representative flow conditions. Computational fluid dynamics predictions were also made to evaluate the performance of some of the current turbulence models in predicting a complex flow such as turbine film-cooling. The renormalization group (RNG) k‐ε turbulence model gave a closer prediction of the overall level of film effectiveness, while the v2‐f turbulence model gave a more accurate representation of the flow physics seen in the experiments.
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Notaristefano, Andrea, et Paolo Gaetani. « Design and Commissioning of a Combustor Simulator Combining Swirl and Entropy Wave Generation ». International Journal of Turbomachinery, Propulsion and Power 5, no 4 (19 octobre 2020) : 27. http://dx.doi.org/10.3390/ijtpp5040027.
Texte intégralRésumé :
Modern aero-engine combustion chambers burn a lean and premixed mixture, generating a turbulent flame which involves large heat-release fluctuations, thus producing unsteady temperature phenomena commonly referred to as entropy waves (EWs). Furthermore, to enhance the fuel air mixing, combustion air is swirled, leading to vorticity disturbances. These instabilities represent one of the biggest challenges in gas turbine design. In this paper, the design and testing of a novel entropy wave generator (EWG) equipped with a swirler generator (SG) are described. The novel EWG will be used in future works on the high-speed test rig at Politecnico di Milano to study the combustor–turbine interaction. The paper shows the process of the EWG geometry and layout. The EWG is able to produce an engine-representative EW, the extreme condition is at the maximum frequency of 110 Hz, a peak-to-valley temperature value of 20 °C and swirling angles of ±25° are measured. By virtue of these results, the proposed system outperforms other EWG devices documented in the literature. Furthermore, the addition of a swirling generator makes this device one of a kind.
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Swar, Rohan, Awatef Hamed, Dongyun Shin, Nathanial Woggon et Robert Miller. « Deterioration of Thermal Barrier Coated Turbine Blades by Erosion ». International Journal of Rotating Machinery 2012 (2012) : 1–10. http://dx.doi.org/10.1155/2012/601837.
Texte intégralRésumé :
A combined experimental and computational study was conducted to investigate the erosion of thermal barrier coated (TBC) blade surfaces by alumina particles ingestion in a single-stage turbine. In the experimental investigation, tests were performed to determine the erosion rates and particle restitution characteristics under different impact conditions. The experimental results show that the erosion rates increase with increased impingement angle, impact velocity, and temperature. In the computational simulations, an Euler-Lagrangian two-stage approach is used in obtaining numerical solutions to the three-dimensional compressible Reynolds-Averaged Navier-Stokes equations and the particles equations of motion in each blade passage reference frame. User defined functions (UDFs) were developed to represent experimentally based correlations for particle surface interaction models and TBC erosion rates models. UDFs were employed in the three-dimensional particle trajectory simulations to determine the particle rebound characteristics and TBC erosion rates on the blade surfaces. Computational results are presented in a commercial turbine and a NASA-designed automotive turbine. The similarities between the erosion patterns in the two turbines are discussed for uniform particle ingestion and for particle ingestion concentrated in the inner and outer 5% of the stator blade span to represent the flow cooling of the combustor liner.
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Mehdizadeh, N. S., et P. Sinaei. « Modelling methane-air turbulent diffusion flame in a gas turbine combustor with artifical neural network ». Aeronautical Journal 113, no 1146 (août 2009) : 541–47. http://dx.doi.org/10.1017/s0001924000003195.
Texte intégralRésumé :
Abstract The present paper reports a way of using an artificial neural network (ANN) for modelling methane-air jet diffusion turbulent flame characteristics, such as temperature and chemical species mass fractions in a gas turbine combustion chamber. Since the neural network needs sets of examples to adapt its synaptic weights in the training phase, we used pre-assumed probability density function (PDF) method and considered chemical equilibrium chemistry model to compute the flame characteristics for generating the examples of input-output data sets. In this approach, flow and mixing field results are presented with a non-linear first order k-ε model. The turbulence model is applied in combination with preassumed β-PDF modelling for turbulence-chemistry interaction. The training algorithm for the neural network is based on a back-propagation supervised learning procedure, and the feed-forward multilayer network is incorporated as neural network architecture. The ability of ANN model to represent a highly non-linear system, such as a turbulent non-premixed flame is illustrated, and it can be summarized that the results of modelling of the combustion characteristics using ANN model are satisfactory, and the CPU-time and memory savings encouraging.
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Cao, Cheng, Yaping Gao, Shaolin Wang, Fuqiang Liu, Cunxi Liu, Yong Mu, Deqing Mei et Gang Xu. « Numerical Investigation on Mechanism of Swirling Flow of the Prefilming Air-Blast Fuel Injector ». Energies 16, no 2 (5 janvier 2023) : 650. http://dx.doi.org/10.3390/en16020650.
Texte intégralRésumé :
Prefilming air-blast atomizers are widely used in modern gas turbine combustors. Due to insufficient awareness of the coupling mechanism of multi-stage swirling flow in gas turbines, there is a lack of effective methods for flow field optimization in combustor. In this study, the effect of some critical parameters on the flow field of a prefilming air-blast atomizer was analyzed with CFD. The parameters include the angle and number of the first swirler blades, the angle of the second swirler blades and the angle of sleeve. Furthermore, the coupling mechanism of two-stage swirling airflows of prefilming air-blast atomizer was discussed. Moreover, the influence of the interaction between two-stage counter swirling airflows on the characteristics of flow field was explained. The results show that with the increase in SNi, the axial length of the primary recirculation zone decreased, while the radial width increased. The starting position of primary recirculation zone (PRZ) moves forward with the increase in SNo. Reducing the sleeve angle β helps to form the primary recirculation zone. The results indicate that it is the transition of tangential velocity of airflow to radial velocity that promotes the formation of the PRZ. These results provide theoretical support for optimization of the flow field in swirl combustor.
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Walker, A. Duncan, Paul A. Denman et James J. McGuirk. « Experimental and Computational Study of Hybrid Diffusers for Gas Turbine Combustors ». Journal of Engineering for Gas Turbines and Power 126, no 4 (1 octobre 2004) : 717–25. http://dx.doi.org/10.1115/1.1772403.
Texte intégralRésumé :
The increasing radial depth of modern combustors poses a particularly difficult aerodynamic challenge for the pre-diffuser. Conventional diffuser systems have a finite limit to the diffusion that can be achieved in a given length and it is, therefore, necessary for designers to consider more radical and unconventional diffuser configurations. This paper will report on one such unconventional diffuser; the hybrid diffuser which, under the action of bleed, has been shown to achieve high rates of diffusion in relatively short lengths. However, previous studies have not been conducted under representative conditions and have failed to provide a complete description of the relevant flow mechanisms making optimization difficult. Utilizing an isothermal representation of a modern gas turbine combustor an experimental investigation was undertaken to study the performance of a hybrid diffuser compared to that of a conventional, single-passage, dump diffuser system. The hybrid diffuser achieved a 53% increase in area ratio within the same axial length generating a 13% increase in the pre-diffuser static pressure recovery coefficient which, in turn, produced a 25% reduction in the combustor feed annulus total pressure loss coefficient. A computational investigation was also undertaken in order to investigate the governing flow mechanisms. A detailed examination of the flow field, including an analysis of the terms within the momentum equation, demonstrated that the controlling flow mechanisms were not simply a boundary layer bleed but involve a more complex interaction between the accelerating bleed flow and the diffusing mainstream flow. A greater understanding of these mechanisms enabled a more practical design of hybrid diffuser to be developed that not only simplified the geometry but also improved the quality of the bleed air making it more attractive for use in component cooling.
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Mardani, Amir, et Alireza Fazlollahi-Ghomshi. « Numerical Investigation of a Double-Swirled Gas Turbine Model Combustor Using a RANS Approach with Different Turbulence–Chemistry Interaction Models ». Energy & ; Fuels 30, no 8 (19 juillet 2016) : 6764–76. http://dx.doi.org/10.1021/acs.energyfuels.6b00452.
Texte intégral
40
Ioannou, Eleni, et Abdulnaser I. Sayma. « Full annulus numerical study of hot streaks propagation in a hydrogen-rich syngas-fired heavy duty axial turbine ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 231, no 5 (16 mai 2017) : 344–56. http://dx.doi.org/10.1177/0957650917706861.
Texte intégralRésumé :
This paper presents a study of the effect of fuel composition on hot streaks propagation in a high-pressure turbine using a full annulus unsteady computational fluid dynamics analysis of the first two stages. Hot streaks result from the inherent non-uniformities of temperature profiles at the exit of the combustion chamber. Variations in composition arise from current challenges requiring gas turbines to adapt to fuel variations driven by the need to reduce CO2 emissions through the use of synthetic hydrogen-rich fuels (syngas) typically generated from the gasification of coal or solid waste. Syngas containing 80% hydrogen has been used in this study in a heavy duty gas turbine modified to accommodate the low calorific value fuel. Calculations were conducted on the baseline gas turbine originally designed for natural gas for the comparative study. Applying combustor representative hot streak profiles, analyses were performed for different hot streak distributions and locations. Analysis of results focused on the segregation of cold and hot fluid patterns and the effects of hot streaks on secondary flows and temperature re-distributions up to the second turbine stage. The hot flow pattern is affected by the fuel composition, resulting in more concentrated thermal wake shapes for syngas when compared to the reference natural gas fuel. In effect, the interaction with the secondary flow leads to more intense flow turning of the pressure side leg of the horseshoe vortex in the first rotor passage. The higher temperature levels in the case of syngas, in combination with the effect of the enhanced secondary flow, result in higher radial spread of the hot fluid that tends to migrate towards the blade hub and tip with the effects being obvious further downstream the first turbine stage.
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Bonasio, Vittorio, et Silvia Ravelli. « Performance Analysis of an Ammonia-Fueled Micro Gas Turbine ». Energies 15, no 11 (24 mai 2022) : 3874. http://dx.doi.org/10.3390/en15113874.
Texte intégralRésumé :
Micro gas turbines fit perfectly with the energy roadmap to 2050: on-site, small scale power generation, combined with heat recovery from exhaust gas, offers an opportunity to deploy primary energy saving and pollutant emission reduction. Moreover, their flexibility enables fuel switching from natural gas (NG) to carbon-free fuels such as hydrogen and ammonia. This study aims to explore the potential of direct combustion of ammonia in a micro gas turbine (MGT), from a thermodynamic point of view. A modeling procedure was developed to simulate the behavior of a 100 kW MGT operating at full and part-load. After validation with NG as fuel, an increasing fraction of ammonia was fed to the combustor to predict performance variations in terms of electric, thermal and total efficiency, as well as exhaust gas composition, for a load range between 40% and 100%. Additional relevant details, related to the interaction between compressor and turbine in the single-shaft arrangement, were discussed through performance maps. Full replacement of NG with ammonia was found to reduce electric efficiency by about 0.5 percentage points (pp), whatever the power output, with a consequent improvement in exhaust gas heat recovery. Thus, total efficiency is maintained at a high level, with values ranging from 74.5% to 79.1% over the investigated load range. The benefit of zero CO2 emissions can be achieved provided that compressor–turbine matching is adjusted to compensate for the reduction in fuel calorific value: at rated power, when the largest fuel input is required, flow rates of air and flue gas decrease by 4.3% and 2.8%, respectively, with an increase in Brayton cycle pressure ratio of 2%.
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Feng, Yuan, Xuesong Li, Xiaodong Ren, Chunwei Gu, Xuan Lv, Shanshan Li et Ziye Wang. « Experimental and Numerical Investigation of the Non-Reacting Flow in a High-Fidelity Heavy-Duty Gas Turbine DLN Combustor ». Energies 15, no 24 (16 décembre 2022) : 9551. http://dx.doi.org/10.3390/en15249551.
Texte intégralRésumé :
A dry, low-NOx (DLN) combustor for a heavy-duty gas turbine using lean premixed technology was studied. A high-fidelity test model was built for the experimental study using particle image velocimetry (PIV). The non-reacting flow in the DLN combustion chamber was investigated experimentally and numerically. The numerical results are in good agreement with the experimental data. The results show that recirculation zones were formed downstream of each swirl nozzle and that the flow pattern in each section was self-similar under different working conditions. For two adjacent swirl nozzles with opposite swirling directions, the entrainment phenomenon was present between their two flows. The two flows gradually mixed with each other and obtained a higher speed. If the two adjacent swirl nozzles had the same swirling direction, then the mixing of the two flows out of the nozzles was not present, resulting in two separate downstream recirculation zones. The interaction of swirling flows out of different nozzles can enhance the turbulent fluctuation inside the combustion chamber. Based on the analysis of the recirculation zones and turbulent kinetic energy (TKE) distribution downstream of each nozzle, it can be found that nozzle coupling results in stronger recirculation and turbulent mixing downstream counterclockwise surrounding nozzles.
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Amin, E. M., G. E. Andrews, M. Pourkashnian, A. Williams et R. A. Yetter. « A Computational Study of Pressure Effects on Pollutant Generation in Gas Turbine Combustors ». Journal of Engineering for Gas Turbines and Power 119, no 1 (1 janvier 1997) : 76–83. http://dx.doi.org/10.1115/1.2815565.
Texte intégralRésumé :
A numerical study of the effect of pressure on the formation of NOx and soot in an axisymmetric 30 deg counterrotating axial swirler lean low-NOx gas turbine combustor has been conducted. This has previously been studied experimentally and this CFD investigation was undertaken to explain the higher than expected NOx emissions. The combustion conditions selected for the present study were 300 K inlet air, 0.4 overall equivalence ratio, and pressures of 1 and 10 bar. The numerical model used here involved the solution of time-averaged governing equations using an elliptic flow-field solver. The turbulence was modeled using algebraic stress modeling (ASM). The thermochemical model was based on the laminar flame let formulation. The conserved scalar/assumed pdf approach was used to model the turbulence chemistry interaction. The study was for two pressure cases at 1 and 10 bar. The turbulence–chemistry interaction is closed by assumption of a clipped Gaussian function form for the fluctuations in the mixture fraction. The kinetic calculations were done separately from the flowfield solver using an opposed laminar diffusion flame code of SANDIA. The temperature and species profiles were made available to the computations through look-up tables. The pollutants studied in this work were soot and NO for which three more additional transport equations are required, namely: averaged soot mass fraction, averaged soot particle number density, and finally averaged NO mass fraction. Soot oxidation was modeled using molecular oxygen only and a strong influence of pressure was predicted. Pressure was shown to have a major effect on soot formation.
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Cha, Chong M., Sungkook Hong, Peter T. Ireland, Paul Denman et Vivek Savarianandam. « Experimental and Numerical Investigation of Combustor-Turbine Interaction Using an Isothermal, Nonreacting Tracer ». Journal of Engineering for Gas Turbines and Power 134, no 8 (11 juin 2012). http://dx.doi.org/10.1115/1.4005815.
Texte intégralRésumé :
Understanding the interaction between the combustor and turbine subsystems of a gas turbine engine is believed to be key in developing focused strategies for improving turbine performance. Past studies have approached the problem starting with an existing turbine rig with inlet conditions provided by “representative” hardware which attempts to mimic some key flow features exiting the combustor. In this paper, experiments are performed which center around complete engine hardware of the combustor, including engine geometry turbine nozzle guide vanes (NGVs) to solely represent the upstream impact of the complete turbine. This domain ensures that the traditional interface between combustor and turbine is sufficiently encompassed and not compromised by obfuscating or limiting effects due to approximating combustor hardware. The full-annular experimental measurements include all components of the velocity and pressure fields at various planar sections perpendicular to the primary flow direction. These include detailed, two-dimensional measurements both upstream and downstream of the NGVs. The combustor is a classic rich-burn design. Passive scalar (CO2) tracing measurements are performed to gain insight into the flow responsible for the temperature fields in the coupled system, including the impact of the NGVs on the upstream flow at the conventional combustor-turbine interface. CFD simulations are used to develop a complete picture of the combustor-turbine interface and the coupling between the two subsystems. The complementary experimental and simulation datasets are together intended to provide a benchmark for future, more traditional turbine rig tests and turbine CFD simulations where inlet conditions are at the exit plane of the combustor.
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Andreini, A., T. Bacci, M. Insinna, L. Mazzei et S. Salvadori. « Hybrid RANS-LES Modeling of the Aerothermal Field in an Annular Hot Streak Generator for the Study of Combustor–Turbine Interaction ». Journal of Engineering for Gas Turbines and Power 139, no 2 (20 septembre 2016). http://dx.doi.org/10.1115/1.4034358.
Texte intégralRésumé :
The adoption of lean-burn technology in modern aero-engines influences the already critical aerothermal conditions at turbine entry, where the absence of dilution holes preserves the swirl component generated by burners and prevents any control on pattern factor. The associated uncertainty and lack of confidence entail the application of wide safety margins in turbine cooling design, with a detrimental effect on engine efficiency. Computational fluid dynamics (CFD) can provide a deeper understanding of the physical phenomena involved in combustor–turbine interaction, especially with hybrid Reynolds-averaged Navier–Stokes (RANS) large eddy simulation (LES) models, such as scale adaptive simulation (SAS), which are proving to overcome the well-known limitations of the RANS approach and be a viable approach to capture the complex flow physics. This paper describes the numerical investigation on a test rig representative of a lean-burn, effusion cooled, annular combustor developed in the EU Project Full Aerothermal Combustor-Turbine interactiOns Research (FACTOR) with the aim of studying combustor–turbine interaction. Results obtained with RANS and SAS were critically compared to experimental data and analyzed to better understand the flow physics, as well as to assess the improvements related to the use of hybrid RANS-LES models. Significant discrepancies are highlighted for RANS in predicting the recirculating region, which has slight influence on the velocity field at the combustor outlet, but affects dramatically mixing and the resulting temperature distribution. The accuracy of the results achieved suggests the exploitation of SAS model with a view to the future inclusion of the nozzle guide vanes in the test rig.
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Lo Presti, Federico, Marwick Sembritzky, Benjamin Winhart, Pascal Post, Francesca di Mare, Alexander Wiedermann, Johannes Greving et Robert Krewinkel. « NUMERICAL INVESTIGATION OF UNSTEADY COMBUSTOR TURBINE INTERACTION FOR FLEXIBLE POWER GENERATION ». Journal of Turbomachinery, 12 août 2021, 1–22. http://dx.doi.org/10.1115/1.4052137.
Texte intégralRésumé :
Abstract In the present study low-frequency disturbances introduced by a periodic load variation have been simulated and superimposed to the inhomogeneous, unsteady flow entering a 3-stage, high-pressure industrial gas turbine fed by a can-type combustion chamber comprising 6 silo-burners. The effects of the unsteadiness realized at the combustor exit have been investigated by means of Detached Eddy Simulations, whereby a density-based solution approach with detailed thermodynamics has been employed. The periodic disturbances at the turbine inlet have been obtained by means of an artificially generated, unsteady field, resulting from a two-dimensional snapshot of the flow field at the combustor exit. Also, a combustor failure has been mimicked by reducing (respectively increasing) the mean temperature in some of the turbine inlet regions corresponding to the outlet of two burners. The propagation and amplitude changes of temperature fluctuations have been analyzed in the frequency domain. Tracking of the temperature fluctuations' maxima at the lowest frequencies revealed characteristic migration patterns indicating that the corresponding fluctuations persist with a non-negligible amplitude up to the last rows. A distinct footprint could also be observed at the same locations when a combustor failure was simulated, showing that, in principle, the early detection of combustor failures is indeed possible.
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Notaristefano, Andrea, et Paolo Gaetani. « The role of turbine operating conditions on combustor-turbine interaction - part 1 : change in expansion ratio ». Journal of Turbomachinery, 16 septembre 2022, 1–43. http://dx.doi.org/10.1115/1.4055642.
Texte intégralRésumé :
Abstract Aeroengine lean-burn combustors release vorticity and temperature perturbations that, interacting with the first turbine stage, impact the stage aerodynamics, blade cooling and noise production. The first of these issues is addressed in this paper that is part 1 of a two-fold contribution. A detailed experimental analysis is carried out to study the impact on the combustor-turbine interaction of the off-design conditions experienced by aero-engines in their duty. Engine-representative disturbances are generated by a combustor simulator able to produce swirling entropy waves. Two injection positions and four injection cases are studied. Experimental measurements are carried out at three traverses: upstream of the stator, at the interstage, and downstream of the rotor. This paper analyses the effect of the stage expansion ratio: two values are studied, namely 1.4 and 1.76, representative of subsonic and transonic flow conditions. They are chosen imposing similar velocity triangles at the rotor inlet. Results show that the swirl profile considerably impacts the stage aerodynamics. The aerothermal flow field downstream of the stator is modified significantly by the combustor disturbances. Conversely, downstream of the rotor, the differences in aerodynamics lessen. However, the entropy wave persists at the stage outlet and its transport depends on both the operating point and the injection position.
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Cubeda, S., L. Mazzei, T. Bacci et A. Andreini. « Impact of Predicted Combustor Outlet Conditions on the Aerothermal Performance of Film-Cooled High Pressure Turbine Vanes ». Journal of Engineering for Gas Turbines and Power 141, no 5 (12 décembre 2018). http://dx.doi.org/10.1115/1.4041038.
Texte intégralRésumé :
Turbine inlet conditions in lean-burn aeroengine combustors are highly swirled and present nonuniform temperature distributions. Uncertainty and lack of confidence associated with combustor-turbine interaction affect significantly engine performance and efficiency. It is well known that only Large-eddy and scale-adaptive simulations (SAS) can overcome the limitations of Reynolds-averaged Navier–Stokes (RANS) in predicting the combustor outlet conditions. However, it is worth investigating the impact of such improvements on the predicted aerothermal performance of the nozzle guide vanes (NGVs), usually studied with RANS-generated boundary conditions. Three numerical modelling strategies were used to investigate a combustor-turbine module designed within the EU Project FACTOR: (i) RANS model of the NGVs with RANS-generated inlet conditions; (ii) RANS model of the NGVs with scale-adaptive simulation (SAS)-generated inlet conditions; (iii) SAS model inclusive of both combustor and NGVs. It was shown that estimating the aerodynamics through the NGVs does not demand particularly complex approaches, in contrast to situations where turbulent mixing is key. High-fidelity predictions of the turbine entrance conditions proved very beneficial to reduce the discrepancies in the estimation of adiabatic temperature distributions. However, a further leap forward can be achieved with an integrated simulation, capable of reproducing the transport of unsteady fluctuations generated from the combustor through the turbine, which play a key role in presence of film cooling. This work, therefore, shows how separate analysis of combustor and NGVs can lead to a poor estimation of the thermal loads and ultimately to a wrong thermal design of the cooling system.
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Kianpour, E., Nor Azwadi Che Sidik et Mohsen Agha Seyyed Mirza Bozorg. « Dynamic Analysis of Flow Field at the End of Combustor Simulator ». Jurnal Teknologi 58, no 2 (15 juillet 2012). http://dx.doi.org/10.11113/jt.v58.1540.
Texte intégralRésumé :
This study was carried out in order to extend database knowledge about the flow field characteristics and define the various flow field contours inside a combustor simulator. The modern gas turbine industries try to get higher engine efficiencies. Brayton cycle is a key to achieve this purpose. According to this cycle industries should increase the turbine inlet temperature to get more engine efficiency and power. However the turbine inlet temperature increasing creates an extremely harsh environment for the downstream critical components such as turbine vanes. In this research a three-dimensional representation of a true Pratt and Whitney aero-engine which studied before in Virginia University was simulated and analyzed to collect essential data. This combustor simulator combined the interaction of two rows of dilution jets, which were staggered in the stream wise direction and aligned in the span wise direction, with that of filmcooling along the combustor liner walls. The overall findings of the study indicate that three-component velocity measurements showed the dilution jet-mainstream interaction produced shear forces and as a result a counter-rotating vortex pair was created. The highest turbulent kinetic energy was found at the top of recirculating region due to the interaction of the second row of dilution jets and mainstream flow. Furthermore, the centers of the counter-rotating vortex pair were spread relatively far apart due to the opposing dilution jets. Along the dilution jet centerline, negative stream wise velocities were measured indicating the recirculation region just downstream of the jet. Into the combustor exit, the acceleration of the flow increased and thereby the uniformity of the velocity profile enhancement was found as well.
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Adams, Maxwell G., Thomas Povey, Benjamin F. Hall, David N. Cardwell, Kam S. Chana et Paul F. Beard. « Commissioning of a Combined Hot-Streak and Swirl Profile Generator in a Transonic Turbine Test Facility ». Journal of Engineering for Gas Turbines and Power 142, no 3 (29 janvier 2020). http://dx.doi.org/10.1115/1.4044224.
Texte intégralRésumé :
Abstract By enhancing the premixing of fuel and air prior to combustion, recently developed lean-burn combustor systems have led to reduced NOx and particulate emissions in gas turbines. Lean-burn combustor exit flows are typically characterized by nonuniformities in total temperature, or so-called hot-streaks, swirling velocity profiles, and high turbulence intensity. While these systems improve combustor performance, the exiting flow-field presents significant challenges to the aerothermal performance of the downstream turbine. This paper presents the commissioning of a new fully annular lean-burn combustor simulator for use in the Oxford Turbine Research Facility (OTRF), a transonic rotating facility capable of matching nondimensional engine conditions. The combustor simulator can deliver engine-representative turbine inlet conditions featuring swirl and hot-streaks either separately or simultaneously. To the best of our knowledge, this simulator is the first of its kind to be implemented in a rotating turbine test facility.The combustor simulator was experimentally commissioned in two stages. The first stage of commissioning experiments was conducted using a bespoke facility exhausting to atmospheric conditions (Hall and Povey, 2015, “Experimental Study of Non-Reacting Low NOx Combustor Simulator for Scaled Turbine Experiments,” ASME Paper No. GT2015-43530.) and included area surveys of the generated temperature and swirl profiles. The survey data confirmed that the simulator performed as designed, reproducing the key features of a lean-burn combustor. However, due to the hot and cold air mixing process occurring at lower Reynolds number in the facility, there was uncertainty concerning the degree to which the measured temperature profile represented that in OTRF. The second stage of commissioning experiments was conducted with the simulator installed in the OTRF. Measurements of the total temperature field at turbine inlet and of the high-pressure (HP) nozzle guide vane (NGV) loading distributions were obtained and compared to measurements with uniform inlet conditions. The experimental survey results were compared to unsteady numerical predictions of the simulator at both atmospheric and OTRF conditions. A high level of agreement was demonstrated, indicating that the Reynolds number effects associated with the change to OTRF conditions were small. Finally, data from the atmospheric test facility and the OTRF were combined with the numerical predictions to provide an inlet boundary condition for numerical simulation of the test turbine stage. The NGV loading measurements show good agreement with the numerical predictions, providing validation of the stage inlet boundary condition imposed. The successful commissioning of the simulator in the OTRF will enable future experimental studies of lean-burn combustor–turbine interaction.