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[EN] In this paper, the unsteady behaviour of a compression-ignited (CI) engine combustion chamber is studied by analysing the results of a Computational Fluid Dynamics (CFD) model through the application of different flow decomposition techniques, aiming to resolve the underlying modal structure of the process. Experimental validation for the combustion simulation is provided, and a methodology for extracting coherent pressure information is proposed in order to provide a suitable input for different analysis methods. These range from straightforward Fourier transform techniques to more sophisticated modal decomposition approaches. In particular Proper Orthogonal Decomposition (POD) is shown to provide valuable insight into the time-spatial structure of the combustion flow field, allowing the establishment of correlations between pressure modes and physical parameters of the combustion, such as the injection timing or the chamber geometry. Dynamic Mode Decomposition (DMD) on the other hand is proven to successfully highlight the link between the frequency of the unsteady energy components and their spatial distribution within the chamber. Advantage is then taken of the modal characterization of the unsteady behaviour in the chamber to showcase how physical parameters such as the spray angle can be modified to optimize the acoustic signature of the combustion process, helping CI internal combustion engines reduce their acoustic environmental impact (C) 2017 The Combustion Institute. Published by Elsevier Inc. All rights reserved. ; The equipment used in this work has been partially supported by FEDER project funds "Dotacidn de infraestructuras cientifico tecnicas para el Centro Integral de Mejora Energetica y Medioambiental de Sistemas de Transporte (CiMeT)" [grant number FEDER-ICTS-2012-06], framed in the operational program of unique scientific and technical infrastructure of the Spanish Government. ; Torregrosa, AJ.; Broatch, A.; Garcia Tiscar, J.; Gómez-Soriano, J. (2018). Modal decomposition of the unsteady ...

In the combustion chamber, temperatures up to 2000K are reached, which exceeds by far the melting point of the liner materials. In order to protect the liner, cool air from the combustion chamber outer casing is injected into the combustor through a large number of sub-millimeter closely-spaced holes (effusion cooling). However, strict environmental legislation has led jet-engine manufacturers to consider techniques that reduce the quantity of air available for cooling. Therefore, cooling system must be carefully designed.However, the size of the holes makes detailed numerical simulations unaffordable. Aerothermal models that mimic effusion cooling behavior are a promising solution. On the other hand, up to now, far too little attention has been paid to a novel effusion cooling technique (compound angle effusion cooling), where cold air injection is not aligned with the hot air flow direction. ; Dans la chambre de combustion, les températures auxquelles les parois sont soumises sont supérieures aux températures de fusion des matériaux. Afin de protéger les parois, une partie de l'air froid provenant du compresseur est injectée par des milliers de perforations (multiperforation).Cependant, face à l'enjeu de la pollution, les motoristes considèrent des solutions qui limitent la quantité d'air disponible pour le refroidissement. Son optimisation s'avère donc capital. Néanmoins, la très petite taille des perforations rend les simulations numériques coûteuses, et des modèles homogènes permettant de s'affranchir du maillage des trous ont gagné de l'importance. De plus, des études récentes ont mis en évidence l'intérêt d'une injection d'air de refroidissement non-alignée avec l'écoulement chaud (solution baptisée dilution giratoire).Cette thèse se propose, d'une part de développer un modèle homogène adapté à ce type nouveaud'injection et d'autre part de contribuer à la compréhension de la multiperforation giratoire.

In the combustion chamber, temperatures up to 2000K are reached, which exceeds by far the melting point of the liner materials. In order to protect the liner, cool air from the combustion chamber outer casing is injected into the combustor through a large number of sub-millimeter closely-spaced holes (effusion cooling). However, strict environmental legislation has led jet-engine manufacturers to consider techniques that reduce the quantity of air available for cooling. Therefore, cooling system must be carefully designed.However, the size of the holes makes detailed numerical simulations unaffordable. Aerothermal models that mimic effusion cooling behavior are a promising solution. On the other hand, up to now, far too little attention has been paid to a novel effusion cooling technique (compound angle effusion cooling), where cold air injection is not aligned with the hot air flow direction. ; Dans la chambre de combustion, les températures auxquelles les parois sont soumises sont supérieures aux températures de fusion des matériaux. Afin de protéger les parois, une partie de l'air froid provenant du compresseur est injectée par des milliers de perforations (multiperforation).Cependant, face à l'enjeu de la pollution, les motoristes considèrent des solutions qui limitent la quantité d'air disponible pour le refroidissement. Son optimisation s'avère donc capital. Néanmoins, la très petite taille des perforations rend les simulations numériques coûteuses, et des modèles homogènes permettant de s'affranchir du maillage des trous ont gagné de l'importance. De plus, des études récentes ont mis en évidence l'intérêt d'une injection d'air de refroidissement non-alignée avec l'écoulement chaud (solution baptisée dilution giratoire).Cette thèse se propose, d'une part de développer un modèle homogène adapté à ce type nouveaud'injection et d'autre part de contribuer à la compréhension de la multiperforation giratoire.

The aim of the work is to create new computer technologies for 3D modelling of heat and mass transfer processes in high-temperature physicochemically reacting environments that will allow to determine the aerodynamics of the flow and heat and mass transfer characteristics of technological processes occurring in the combustion chambers in existing coal-fired thermal power plants of the Republic of Kazakhstan. The novelty of the research lies in the use of the latest information technologies of 3D modelling, which will enable project participants to obtain new data on complex heat and mass transfer processes when burning pulverized coal in real combustion chambers operating in Kazakhstan's Thermal Power Plants (TPP). A numerical simulation, including thermodynamic, kinetic and threedimensional computer simulation of heat and mass transfer processes when burning low-grade fuel, will allow finding optimal conditions for setting adequate physical, mathematical and chemical models of the technological process of combustion of burning high ash coals. The computer modelling methods proposed for the development are new and technically feasible, since coal-fired power plants all over the world use all types of coal. The developed technologies will allow replacing or eliminating the conduct of expensive and labour-consuming natural experiments on coal-fired power plants.

"January 23, 1952." ; Includes bibliographical references (p. 6). ; Mode of access: Internet.

Since combustion efficiency in modern jet engines has stabilized, attention has turned to improving the combustor by improving the thrust-to-weight ratio. The Ultra Compact Combustor (UCC) is a means to reduce the weight of the combustor while ensuring exhaust meets increasingly stringent government emission standards. Combustion occurs within the UCC under a g-load in the circumferential direction, which maintains combustion efficiency while decreasing axial combustor length. Previous analysis optimized the combustion chamber flame characteristics with a common upstream air source. Previously, issues for the UCC were inspired by integration into a traditional axial turbojet. The focus of this investigation was to increase migration of the hot combustion products to the middle of the hybrid vane's exit plane. This was done by varying the dimensions of the UCC combustion cavity, the air driver configuration into the cavity, as well as adding a radial vane cavity into the center-body guide vanes. In order to accomplish this, a temperature measurement collection technique called thin filament pyrometry was implemented to obtain high fidelity data. Also, the AFIT UCC required an accurate initial emissions baseline to be established; this baseline consisted of collecting five different gaseous species for each considered geometry. These data points were then compared against each other and previously collected temperature values. Optimal exit efficiency and temperature profiles were obtained through modifications to the hybrid vane passage and the air driver geometry.

In this paper the authors present a 0D-3D approach for numerical modelling of a waste-to-energy plant located in Italy in different operating conditions. This innovative methodology combines a 0D lumped parameters model, able to describe the processes of solid and gaseous combustion and the heat transfer within the first radiant channel, with a detailed 3D CFD simulation of the thermo-fluid-dynamic field within the plant combustion chamber. Results from the 0D model allow the definition of input data and boundary conditions for detailed 3D CFD simulation of the thermo-fluid-dynamic field within the plant combustion chamber. In this way, the T2S temperature can be determined according to actual definition of European legislation. The developed numerical tool is generally applicable to any waste-to-energy plant, and is here applied for the characterization of different operating conditions of an Italian WTE plant. The analysis allows the verification of the constraints imposed by the European legislation on the temperature of the combustion products and the identification of any issues related to the plant operation. In order to demonstrate the performance of the proposed numerical modelling approach, in this paper the authors present and discuss the results obtained by applying the model to one day-averaged operating condition of a WTE plant in Italy. Input parameters are obtained from available measurements and numerical results are validated against experiments showing a good agreement. Data and results in this paper are presented in a normalized form for confidentiality.

This paper presents an analysis of the gas turbine real process (with all losses included) before and after a major maintenance. The analysis of both gas turbine operating regimes is based on data measured during its exploitation. Contrary to authors' expectations, the major maintenance process did not result either in any decrease in losses or increase in efficiencies for the majority of the gas turbine components. However, the major maintenance influenced positively the gas turbine combustion chambers (reduction in losses and increase in the combustion chambers efficiency). After the major maintenance, the overall process efficiency decreased from 43.796% to 41.319% due to a significant decrease in the air mass flow rate and to an increase in the fuel mass flow rate in combustion chambers. A decrease in the gas turbine produced cumulative and useful power after a major maintenance also increased the specific fuel consumption.

In India, Silk industry plays an important part in textile industry. Muga silk, the golden yellow silk is quite unique to Assam, North-east India where its production is regarded as an important tool for economic development. But, outdated manufacturing technology is followed during the silk production in Assam. The existing cooking process of silk cocoons consists of boiling of silk cocoons in a stainless steel vessel along with water and soda in an open fireplace which is highly energy inefficient. Therefore, two modified systems have been designed; one having cylindrical boiling chamber (vessel) and the other having spherical boiling chamber (vessel). Both the chambers are having a cocoon heating chamber associated with them for cooking and drying of silk cocoons simultaneously. These designs are further classified into two types of designs based on channel and nozzle type combustion chambers. Therefore, the main objective of this paper is to improve the existing designs to maximize the utilization of heat carried by the combustion gases. These modified systems are analysed by using Computational Fluid Dynamics (CFD) selecting standard k–є model. From the analysis, it is seen that these new systems having nozzle type combustion chambers are more efficient than the systems having cylindrical combustion chambers and if these systems are used in silk production, it will be very beneficial for the silk industry as well as for our society.

"Enclosure." ; Evaluation Report 110. 15th June 1945-- page 1. ; Target No. 4/48e, 5/111-- page 1. ; File number 60057. ; "Note: the Publication Board, in approving and disseminating this report, hopes that it will be of direct benefit to U.S. science and industry. Interested parties should realize that some products and processes described may also be the subject of U.S. patents. Accordingly, it is recommended that the usual patent study be made before pursuing practical applications." ; "This report has been declassified and released to the Office of Publication Board by the War and Navy Departments." ; "Combined Intelligence Objectives Sub-Committee"--P. 1. ; At head of title: Office of the Publication Board, Department of Commerce. ; Reproduced from typewritten copy. ; Cover title. ; Mode of access: Internet.

The primary purpose of this study is to evaluate the ability of LES, with a turbulent combustion model based on steady flamelets, to predict the flame stabilization mechanisms in an industrial can combustor at full load conditions. The test case corresponds to the downscaled Siemens can combustor tested in the high pressure rig at the DLR. The effects of the wall temperature on the prediction capabilities of the codes is investigated by imposing several heat transfer conditions at the pilot and chamber walls. The codes used for this work are Alya and OpenFOAM, which are well established CFD codes in the fluid mechanics community. Prior to the simulation, results for 1-D laminar flames at the operating conditions of the combustor are compared with the detailed solutions. Subsequently, results from both codes at the mid-plane are compared against the experimental data available. Acceptable results are obtained for the axial velocity, while discrepancies are more evident for the mixture fraction and the temperature, particularly with Alya. However, both codes showed that the heat losses influence the size and length of the pilot and main flame. ; The research leading to these results has received funding through the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7, 2007-2013) under the grant agreement No. FP7-290042 for the project COPA-GT and the European Union's Horizon 2020 Programme (2014-2020) and from Brazilian Ministry of Science, Technology and Innovation through Rede Nacional de Pesquisa (RNP) under the HPC4E Project, grant agreement No. 689772. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Red Española de Supercomputación (RES). ; Peer Reviewed ; Postprint (author's final draft)

The primary purpose of this study is to evaluate the ability of LES, with a turbulent combustion model based on steady flamelets, to predict the flame stabilization mechanisms in an industrial can combustor at full load conditions. The test case corresponds to the downscaled Siemens can combustor tested in the high pressure rig at the DLR. The effects of the wall temperature on the prediction capabilities of the codes is investigated by imposing several heat transfer conditions at the pilot and chamber walls. The codes used for this work are Alya and OpenFOAM, which are well established CFD codes in the fluid mechanics community. Prior to the simulation, results for 1-D laminar flames at the operating conditions of the combustor are compared with the detailed solutions. Subsequently, results from both codes at the mid-plane are compared against the experimental data available. Acceptable results are obtained for the axial velocity, while discrepancies are more evident for the mixture fraction and the temperature, particularly with Alya. However, both codes showed that the heat losses influence the size and length of the pilot and main flame. ; The research leading to these results has received funding through the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7, 2007-2013) under the grant agreement No. FP7-290042 for the project COPA-GT and the European Union's Horizon 2020 Programme (2014-2020) and from Brazilian Ministry of Science, Technology and Innovation through Rede Nacional de Pesquisa (RNP) under the HPC4E Project, grant agreement No. 689772. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Red Española de Supercomputación (RES). ; Peer Reviewed ; Postprint (author's final draft)

[EN] Cylinder resonance phenomenon in reciprocating engines consists of high-frequency pressure oscillations excited by the combustion. The frequency of these oscillations is proportional to the speed of sound on pent-roof combustion chambers and henceforth the resonance frequency can be used to estimate the trapped mass, but in bowl-in-piston chambers a geometrical factor must be added in order to deal with the bowl disturbance. This paper applies the finite element method (FEM) to provide a resonance calibration for new design combustion chambers, which are commonly dominated by the bowl geometry near the top dead centre. The resonance calibration does not need any sensor information when it is solved by a FEM procedure, and consequently, is free from measurement errors. The calibration is proven to be independent of the chamber conditions and the results obtained are compared with experimental data by using spectral techniques and measuring precisely the trapped mass.[EN] ; This research has been partially supported by the European Union in framework of the POWERFUL project, seventh framework program FP7/2007-2013, theme 7, sustainable surface transport (grant agreement number SCP8-GA-2009-234032). ; Broatch Jacobi, JA.; Guardiola, C.; Bares-Moreno, P.; Denia Guzmán, FD. (2016). Determination of the resonance response in an engine cylinder with a bowl-in-piston geometry by the finite element method for inferring the trapped mass. International Journal of Engine Research. 17(5):534-542. https://doi.org/10.1177/1468087415589701 ; S ; 534 ; 542 ; 17 ; 5 ; Powell, J. D. (1993). Engine Control Using Cylinder Pressure: Past, Present, and Future. Journal of Dynamic Systems, Measurement, and Control, 115(2B), 343-350. doi:10.1115/1.2899074 ; Desantes, J. M., Galindo, J., Guardiola, C., & Dolz, V. (2010). Air mass flow estimation in turbocharged diesel engines from in-cylinder pressure measurement. Experimental Thermal and Fluid Science, 34(1), 37-47. doi:10.1016/j.expthermflusci.2009.08.009 ; Finol, C. A., & ...