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1
Guénan, Karine. "L’avion à hydrogène ZEROe : défis technologiques et impacts sur l’écosystème". Annales des Mines - Réalités industrielles Mai 2024, n. 2 (14 giugno 2024): 99–103. http://dx.doi.org/10.3917/rindu1.242.0099.
Testo completoAbstract (sommario):
L’aviation, symbole de mobilité et de rapprochement, doit réinventer son futur, pour répondre aux exigences de neutralité carbone d’ici 2050. L’hydrogène se présente comme une solution d’avenir pour la décarbonation de nombreuses industries. Cependant, son adoption dans l’aéronautique nécessitera des avancées majeures, de la production et distribution à grande échelle d’hydrogène vert, alimentées par les énergies renouvelables, à la conception de réservoirs cryogéniques sécurisés, en passant par l’adaptation des équipements et infrastructures aéroportuaires. Airbus se positionne en champion de cette transition, collaborant avec des partenaires, leaders mondiaux dans leur domaine respectif, pour concrétiser son ambition. Les concepts novateurs de l’avion à hydrogène ZEROe, propulsé par des piles à combustible ou des moteurs à combustion d’hydrogène, promettent une réduction significative des émissions de CO 2 . L’objectif est clair : transformer l’industrie aéronautique, pour un avenir plus durable, sûr et uni.
2
Mahfoudi, El-Ahcene, Abderrahmane Gahmousse, Athmane Harizi, Kamel Talbi e Abdellah Hadjadj. "Simulation numérique de l’écoulement compressible supersonique Application aux tuyères propulsives à combustible liquide hydrogène". Journal of Renewable Energies 15, n. 3 (23 ottobre 2023): 365–72. http://dx.doi.org/10.54966/jreen.v15i3.327.
Testo completoAbstract (sommario):
Ce travail porte sur la simulation numérique de l’écoulement supersonique adapté dans les tuyères propulsives où le gaz d’essai supposé parfait est le gaz de combustion de l’Hydrogène. Il vise à déterminer les paramètres de l’écoulement Eulérien supersonique dans la tuyère convergente divergente. La méthode numérique utilisée pour la résolution de l’écoulement est basée sur une approche des volumes finis en coordonnées généralisées. L’intégration du système pour les équations de conservation d’Euler s’effectue sur un volume élémentaire quadrilatère. Dans cette étude, le traitement des flux convectifs est effectué en utilisant la méthode de Roe. Pour la discrétisation temporelle des équations, un schéma explicite de type Runge-Kutta du second ordre est utilisé.
3
Studer, Etienne, Danièle Abdo, Sonia Benteboula, Gilles Bernard-Michel, Nadia Coulon, Frédéric Dabbene, Sergey Kudriakov et al. "Sûreté des réacteurs : la connaissance du risque hydrogène enrichie de 20 ans de R&D". Revue Générale Nucléaire, n. 1 (gennaio 2018): 48–53. http://dx.doi.org/10.1051/rgn/20181048.
Testo completoAbstract (sommario):
Le CEA s’est doté d’une compétence forte pour comprendre, modéliser et prévenir le risque hydrogène dans les installations nucléaires. À partir du milieu des années 1990, une approche couplée numérique et expérimental a été mise en oeuvre pour atteindre ces objectifs : le projet TONUS pour se doter d’outils numériques pour traiter de la distribution et de la combustion de l’hydrogène et le projet MISTRA pour alimenter ces modèles numériques en données expérimentales « CFD grade » pour la distribution de l’hydrogène et l’efficacité des moyens de prévention. Ces connaissances et ces outils ont conforté les démonstrations de sûreté des installations existantes tant civiles que militaires et contribuent à la conception de nouveaux réacteurs toujours plus sûrs. Enfin, elles sont valorisées pour la sûreté des installations industrielles liées à l’hydrogène vecteur d’énergie.
4
De Giorgi, M. G., G. Cinieri, G. Marseglia, Z. Ali Shah e Ghazanfar Mehdi. "Combustion Efficiency of Carbon-neutral Fuel using Micro-Combustor Designed for Aerospace Applications". Journal of Physics: Conference Series 2716, n. 1 (1 marzo 2024): 012091. http://dx.doi.org/10.1088/1742-6596/2716/1/012091.
Testo completoAbstract (sommario):
Abstract Recent advancements in the field of micro combustor research are growing for achieving high-performance systems in micro power generation and microelectromechanical devices. To mitigate the hazardous emissions from carbon fuels, as an alternative, zero-carbon-free fuels ammonia, and hydrogen are being explored in micro combustion processes. The distinctive feature of a micro combustor lies in its significantly higher area to volume ratio in comparison with traditional combustion systems, leading to accelerated combustion reaction rates. However, the small size of micro combustors poses a challenge in achieving efficient mixing of highly reactive fuels like hydrogen and ammonia with oxidizers. The unique properties of micro combustors can lead to differences in the combustion behavior of hydrogen and ammonia compared to larger-scale combustion systems. Hence, examining the performance of carbon-free fuels in micro combustors is crucial for the advancement of clean energy combustion systems. A numerical investigation on a Y-shaped micro-combustor was carried out to identify the aspects of non-premixed combustion of ammonia/air and hydrogen/air. The findings reveal that in the case of hydrogen combustion, stable flames were reached, even at low equivalence ratios. Therefore, the distinct combustion properties of hydrogen and ammonia result in varying NOx emissions, with hydrogen generally leading to higher NOx levels due to its higher flame temperature and increased thermal NOx production.
5
Serbin, Serhiy, Mykola Radchenko, Anatoliy Pavlenko, Kateryna Burunsuz, Andrii Radchenko e Daifen Chen. "Improving Ecological Efficiency of Gas Turbine Power System by Combusting Hydrogen and Hydrogen-Natural Gas Mixtures". Energies 16, n. 9 (22 aprile 2023): 3618. http://dx.doi.org/10.3390/en16093618.
Testo completoAbstract (sommario):
Currently, the issue of creating decarbonized energy systems in various spheres of life is acute. Therefore, for gas turbine power systems including hybrid power plants with fuel cells, it is relevant to transfer the existing engines to pure hydrogen or mixtures of hydrogen with natural gas. However, significant problems arise associated with the possibility of the appearance of flashback zones and acoustic instability of combustion, an increase in the temperature of the walls of the flame tubes, and an increase in the emission of nitrogen oxides, in some cases. This work is devoted to improving the efficiency of gas turbine power systems by combusting pure hydrogen and mixtures of natural gas with hydrogen. The organization of working processes in the premixed combustion chamber and the combustion chamber with a sequential injection of ecological and energy steam for the “Aquarius” type power plant is considered. The conducted studies of the basic aerodynamic and energy parameters of a gas turbine combustor working on hydrogen-containing gases are based on solving the equations of conservation and transfer in a multicomponent reacting system. A four-stage chemical scheme for the burning of a mixture of natural gas and hydrogen was used, which allows for the rational parameters of environmentally friendly fuel burning devices to be calculated. The premixed combustion chamber can only be recommended for operations on mixtures of natural gas with hydrogen, with a hydrogen content not exceeding 20% (by volume). An increase in the content of hydrogen leads to the appearance of flashback zones and fuel combustion inside the channels of the swirlers. For the combustion chamber of the combined-cycle power plant “Vodoley”, when operating on pure hydrogen, the formation of flame flashback zones does not occur.
6
Lee, Jaeyoung, Chang Bum Sohn, Young Sik Jeong e Young Bae Kim. "A Numerical Analysis of Premixed Hydrogen–Methane Flame with Three Different Header Types of Combustor". Fire 7, n. 10 (10 ottobre 2024): 361. http://dx.doi.org/10.3390/fire7100361.
Testo completoAbstract (sommario):
This study investigated the impact of thin-flame combustor design on hydrogen flame characteristics and combustion performance through numerical simulations. Differences in the flame shape and combustibility between pure methane and pure hydrogen combustion were analyzed. Three combustor header shapes (flat, concave, and convex) were modeled to assess the influence of header shape on flame behavior. The results revealed distinct flow patterns, with the concave header promoting strong central flows and the convex header dispersing the flow outward. Temperature field analysis indicated that the hydrogen flames had higher temperatures and shorter quenching distances than the methane flames. A comparative analysis of combustion products was conducted to evaluate combustion performance and NOx emissions. The findings showed that the concave header had a high combustibility, with hydrogen combustion producing greater temperatures and NOx fractions than methane combustion.
7
Franco, Alessandro, e Michele Rocca. "Industrial Decarbonization through Blended Combustion of Natural Gas and Hydrogen". Hydrogen 5, n. 3 (26 agosto 2024): 519–39. http://dx.doi.org/10.3390/hydrogen5030029.
Testo completoAbstract (sommario):
The transition to cleaner energy sources, particularly in hard-to-abate industrial sectors, often requires the gradual integration of new technologies. Hydrogen, crucial for decarbonization, is explored as a fuel in blended combustions. Blending or replacing fuels impacts combustion stability and heat transfer rates due to differing densities. An extensive literature review examines blended combustion, focusing on hydrogen/methane mixtures. While industrial burners claim to accommodate up to 20% hydrogen, theoretical support is lacking. A novel thermodynamic analysis methodology is introduced, evaluating methane/hydrogen combustion using the Wobbe index. The findings highlight practical limitations beyond 25% hydrogen volume, necessitating a shift to “totally hydrogen” combustion. Blended combustion can be proposed as a medium-term strategy, acknowledging hydrogen’s limited penetration. Higher percentages require burner and infrastructure redesign.
8
Wang, Kefu, Feng Li, Tao Zhou e Yiqun Ao. "Numerical Study of Combustion and Emission Characteristics for Hydrogen Mixed Fuel in the Methane-Fueled Gas Turbine Combustor". Aerospace 10, n. 1 (10 gennaio 2023): 72. http://dx.doi.org/10.3390/aerospace10010072.
Testo completoAbstract (sommario):
The aeroderivative gas turbine is widely used as it demonstrates many advantages. Adding hydrogen to natural gas fuels can improve the performance of combustion. Following this, the effects of hydrogen enrichment on combustion characteristics were analyzed in an aeroderivative gas turbine combustor using CFD simulations. The numerical model was validated with experimental results. The conditions of the constant mass flow rate and the constant energy input were studied. The results indicate that adding hydrogen reduced the fuel residues significantly (fuel mass at the combustion chamber outlet was reduced up to 60.9%). In addition, the discharge of C2H2 and other pollutants was reduced. Increasing the volume fraction of hydrogen in the fuel also reduced CO emissions at the constant energy input while increasing CO emissions at the constant fuel mass flow rate. An excess in the volume fraction of added hydrogen changed the combustion mode in the combustion chamber, resulting in fuel-rich combustion (at constant mass flow rate) and diffusion combustion (at constant input power). Hydrogen addition increased the pattern factor and NOx emissions at the outlet of the combustion chamber.
9
Tamang, Sajan, e Heesung Park. "Numerical investigation on the dry low NOx of hydrogen combustion". Journal of Physics: Conference Series 2968, n. 1 (1 febbraio 2025): 012009. https://doi.org/10.1088/1742-6596/2968/1/012009.
Testo completoAbstract (sommario):
Abstract Globally, energy is predominantly generated through the combustion of fossil fuels. However, the emissions from these fuels severely impact the ecological balance and environment. As a result, there is a growing emphasis on clean and renewable energy sources as alternatives. Hydrogen is a promising and clean energy source for gas turbines, transportation, and industrial applications. Nevertheless, due to significant differences in hydrogen’s thermophysical properties, it cannot be directly integrated into conventional combustion systems. Therefore, a specialized micromix combustion model must be developed to achieve stable combustion with low dry NOx emissions. In this study, a novel micromix combustor is developed based on the cross-flow mixing of air and injected hydrogen fuel. Under this concept, hydrogen combustion occurs through diffusion-type flames, with the reaction taking place in a very short time. This micromix combustor design ensures inherently stable combustion, resistant to flashback while maintaining low dry NOx emissions. The results indicate that the stability of the flame structure and thermal NOx emissions are controlled by the operating equivalence ratios. A stable hydrogen flame was particularly formed in the shear regions between the two vortices. Thermal NOx generation was strongly influenced by the flame front temperature, with measurements ranging from approximately 0.66 to 11.14 ppm (at 15% oxygen concentration). Consequently, thermal NOx emissions increased by up to 16 times under an equivalence ratio of 0.5.
10
Huang, Juan-Chen, Yu-Hsuan Lai, Jeng-Shan Guo e Jaw-Yen Yang. "Simulation of Two-Dimensional Scramjet Combustor Reacting Flow Field Using Reynolds Averaged Navier-Stokes WENO Solver". Communications in Computational Physics 18, n. 4 (ottobre 2015): 1181–210. http://dx.doi.org/10.4208/cicp.190115.210715s.
Testo completoAbstract (sommario):
AbstractThe non-equilibrium chemical reacting combustion flows of a proposed long slender scramjet system were numerically studied by solving the turbulent Reynolds averaged Navier-Stokes (RANS) equations. The Spalart-Allmaras one equation turbulence model is used which produces better results for near wall and boundary layer flow field problems. The lower-upper symmetric Gauss-Seidel implicit scheme, which enables results converge efficiently under steady state condition, is combined with the weighted essentially non-oscillatory (WENO) scheme to yield an accurate simulation tool for scramjet combustion flow field analysis. Using the WENO schemes high-order accuracy and its non-oscillatory solution at flow discontinuities, better resolution of the hypersonic flow problems involving complex shock-shock/shock-boundary layer interactions inside the flow path, can be achieved. Two types of scramjet combustor with cavity-based and strut-based fuel injector were considered as the testing models. The flow characteristics with and without combustion reactions of the two types combustor model were studied with a transient hydrogen/oxygen combustion model. The detailed results of aerodynamic data are obtained and discussed, moreover, the combustion properties of varying the equivalent ratio of hydrogen, including the concentration of reacting species, hydrogen and oxygen, and the reacting products, water, are demonstrated to study the combustion process and performance of the combustor. The comparisons of flow field structures, pressure on wall and velocity profiles between the experimental data and the solutions of the present algorithms, showed qualitatively as well as the quantitatively in good agreement, and validated the adequacy of the present simulation tool for hypersonic scramjet reacting flow analysis.
11
Waitz, Ian A., Gautam Gauba e Yang-Sheng Tzeng. "Combustors for Micro-Gas Turbine Engines". Journal of Fluids Engineering 120, n. 1 (1 marzo 1998): 109–17. http://dx.doi.org/10.1115/1.2819633.
Testo completoAbstract (sommario):
The development of a hydrogen-air microcombustor is described. The combustor is intended for use in a 1 mm2 inlet area, micro-gas turbine engine. While the size of the device poses several difficulties, it also provides new and unique opportunities. The combustion concept investigated is based upon introducing hydrogen and premixing it with air upstream of the combustor. The wide flammability limits of hydrogen-air mixtures and the use of refractory ceramics enable combustion at lean conditions, obviating the need for both a combustor dilution zone and combustor wall cooling. The entire combustion process is carried out at temperatures below the limitations set by material properties, resulting in a significant reduction of complexity when compared to larger-scale gas turbine combustors. A feasibility study with initial design analyses is presented, followed by experimental results from 0.13 cm3 silicon carbide and steel microcombustors. The combustors were operated for tens of hours, and produced the requisite heat release for a microengine application over a range of fuel-air ratios, inlet temperatures, and pressures up to four atmospheres. Issues of flame stability, heat transfer, ignition and mixing are addressed. A discussion of requirements for catalytic processes for hydrocarbon fuels is also presented.
12
Kim, Jonghyun, e Jungsoo Park. "Conceptual Approach to Combustor Nozzle and Reformer Characteristics for Micro-Gas Turbine with an On-Board Reforming System: A Novel Thermal and Low Emission Cycle". Sustainability 12, n. 24 (17 dicembre 2020): 10558. http://dx.doi.org/10.3390/su122410558.
Testo completoAbstract (sommario):
In order to implement moderate or intensive low oxygen dilution (MILD) combustion, it is necessary to extend the flame stability and operating range. In the present study, the conceptual designs of a combustor single nozzle and reformer were numerically suggested for a micro-gas turbine with an on-board reformer. The target micro-gas turbine achieved a thermal power of 150 kW and a turbine inlet temperature (TIT) of 1200 K. Studies on a nozzle and reformer applying an open-loop concept have been separately conducted. For the nozzle concept, a single down-scaled nozzle was applied based on a reference nozzle for a heavy-duty gas turbine. The nozzle can achieve a good mixture with a high swirl with a splined swirl curve lower NOx emissions and smaller pressure drop in the combustor. The concept of the non-catalytic partial-oxidation reforming reformate was designed using the combustor outlet temperature (COT) of the exhaust gas. Feasible hydrogen yields were mapped through the reformer. Based on the hydrogen yields from the reformer, hydrogen was added to the nozzle to investigate its combustion behavior. By increasing the hydrogen addition and decreasing the O2 fraction, the OH concentrations were decreased and widely distributed similar to the fundamental characteristics of MILD combustion.
13
Goldfeld, Marat, e Alexey Starov. "Scheme of Hydrogen Ignition in Duct with Shock Waves". Siberian Journal of Physics 9, n. 2 (1 giugno 2014): 116–27. http://dx.doi.org/10.54362/1818-7919-2014-9-2-116-127.
Testo completoAbstract (sommario):
In article results of the analysis of processes of self-ignition and combustion propagation are given in the multi-injector combustion chamber with high supersonic speeds of an air flow. It is established that fuel ignition at high Mach numbers, bringing to flame propagation on all volume of combustor and combustion stabilization, happens not in recirculation area behind a step, and in the field of interaction of shock waves with an boundary layer on walls or behind this area downstream near an angular point of the combustion chamber. The scheme of development of process of combustion in the combustion chamber with significantly three-dimensional configuration is in details considered
14
Ma, Yi, Wenhua Yuan, Shaomin Zhao e Hongru Fang. "Premixed Combustion Characteristics of Hydrogen/Air in a Micro-Cylindrical Combustor with Double Ribs". Energies 17, n. 20 (17 ottobre 2024): 5165. http://dx.doi.org/10.3390/en17205165.
Testo completoAbstract (sommario):
Hydrogen is a promising zero-carbon fuel, and its application in the micro-combustor can promote carbon reduction. The structural design of micro-combustors is crucial for combustion characteristics and thermal performance improvement. This study investigates the premixed combustion characteristics of hydrogen/air in a micro-cylindrical combustor with double ribs, using an orthogonal design method to assess the impact of various geometric parameters on thermal performance. The results indicate that the impact of rib height, rib position, and inclined angle is greater than rib width and their interactions, while their influence decreases in that order. Increased rib height improves mean wall temperature and exergy efficiency due to an expanded recirculation region and increased flame–wall contact, but negatively affects temperature uniformity and combustion efficiency. Although double ribs enhance performance, placing them too close may reduce heat transfer due to the low-temperature region between the ribs. When the double ribs are positioned at the axial third equinoxes of the micro-combustor, the highest mean wall temperature is achieved. Meanwhile, with a rib height of 0.3 and an inclined angle of 45°, the micro-combustor achieves optimal thermal performance, with the mean wall temperature increasing by 61.32 K.
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Carrier, D. M., e R. J. Wetton. "Prediction of Combustion Performance of Aviation Kerosines Using a Novel Premixed Flame Technique". Journal of Engineering for Gas Turbines and Power 110, n. 1 (1 gennaio 1988): 100–104. http://dx.doi.org/10.1115/1.3240071.
Testo completoAbstract (sommario):
A novel method for predicting aviation fuel combustion performance has been developed in which the sooting point of a premixed flame is detected automatically. Comparisons with full-scale combustor data confirm that the technique is a more realistic index of combustion quality than Smoke Point or hydrogen content.
16
Zvada, Branislav, Radovan Nosek, Peter Ďurčanský, Andrej Kapjor e Nikola Kantová Čajová. "Numerical Predictive Combustion Model of Hydrogen Enriched Natural Gas". MATEC Web of Conferences 369 (2022): 03003. http://dx.doi.org/10.1051/matecconf/202236903003.
Testo completoAbstract (sommario):
Hydrogen was established as one of the main pillars of energy stability in the Europe Union. One of the ways how to achieve this goal is natural gas enriched with hydrogen. Due to this is very important to know the properties of this fuel and its behaviour during combustion. The main scope of the research is to provide a better understanding of the emissions, efficiency, and performance of the heat source when combusting hydrogen and gas fuel mixture. In this paper is described hydrogen characteristics, hydrogen fuel preparation, an overview of gas fuel combustion in gas appliances with the hydrogen additive, a mathematical model for the combustion process estimation. In the conclusion, multiple predictive models were compared. We can state that, based on calculations of a numerical predictive model, as hydrogen concentration raised emissions, as nitrogen, carbon dioxide, wet exhaust, and water, are decreasing.
17
Stępień, Zbigniew, e Wiesława Urzędowska. "Tłokowe silniki spalinowe zasilane wodorem – wyzwania". Nafta-Gaz 77, n. 12 (dicembre 2021): 830–40. http://dx.doi.org/10.18668/ng.2021.12.06.
Testo completoAbstract (sommario):
W artykule opisano potencjał wodoru jako kluczowego nośnika energii w przyszłości. Wskazano przy tym, że spośród znanych paliw alternatywnych wodór stanowi najlepsze rozwiązanie w zakresie ograniczenia lub nawet całkowitego wyeliminowania niebezpiecznych emisji, w tym GHG z pojazdów. Dlatego wodór jest powszechnie postrzegany jako perspektywiczne, zrównoważone paliwo, i to zarówno do zasilania tłokowych silników spalinowych, jak i ogniw paliwowych. Ze względu na zaawansowany rozwój tłokowych silników spalinowych i ich szeroką dostępność mogą one pełnić rolę technologii pomostowej dla szerokiego rozpowszechnienia wodoru jako paliwa. W konsekwencji tłokowy silnik spalinowy zasilany wodorem może stanowić technologię przejściową wykorzystywaną jako napęd różnego typu pojazdów samochodowych, a w szczególności ciężarowych. W dalszej części artykułu szeroko opisano wyzwania, jakie w dalszym ciągu pozostają do rozwiązania, aby zasilane wodorem silniki spalinowe stały się konkurencyjną alternatywą zarówno dla silników napędzanych paliwami węglowodorowymi, jak i napędów elektrycznych. Wyzwania te podzielono na pięć obszarów. W każdym z nich opisano problemy techniczne, konstrukcyjne i materiałowe wymagające dalszych badań i poszukiwania rozwiązań bądź doskonalenia stosowanych już środków zaradczych. W pierwszym obszarze zwrócono uwagę na szkodliwe oddziaływanie wodoru na metale i ich stopy oraz inne materiały. Dyfuzja cząsteczek wodoru w głąb materiału powoduje zmiany w strukturze, a następnie może prowadzić do tzw. kruchości wodorowej, wynikających stąd mikropęknięć wewnątrz materiałów i tzw. korozji wodorowej. Ponadto bardzo niska smarność wodoru powoduje przedwczesne zużycie elementów współpracujących ze sobą, jak zawory dolotowe i przylgnie gniazd zaworowych silnika, iglice wtryskiwaczy i ich gniazda. W drugim obszarze opisano potrzebę dalszej optymalizacji procesów zasilania wodorem, jego zapłonu oraz strategii procesu spalania. Wynika to z konieczności przeciwdziałania przedwczesnemu zapłonowi paliwa i zapobiegania procesom nienormalnego spalania. W trzecim obszarze opisano problemy związane z konstrukcyjnym adaptowaniem i optymalizacją głowic cylindrowych. Jest to wymagane dla ich dostosowania do silników zasilanych wodorem. W głowicach tych muszą być umieszczone wtryskiwacze (wtrysk typu DI) o zwiększonej, w porównaniu z konwencjonalnymi silnikami, wydajności i odpowiednio ukształtowane (zoptymalizowane pod kątem większego odprowadzenia ciepła) kanały płynu chłodzącego. Zwrócono też uwagę na inne elementy konstrukcyjne silnika i systemy współdziałające z silnikiem, które muszą być dostosowane w przypadku zasilania wodorem. W czwartym obszarze przedstawiono wyzwania związane z dalszą optymalizacją wielokrotnego, precyzyjnie sterowanego bezpośredniego wtrysku wodoru do silnika. Piąty, ostatni obszar dotyczył układu smarowania silnika i oleju smarowego. Wskazano na odmiennie przebiegający proces stopniowej utraty właściwości smarnych oleju w porównaniu do oleju smarowego eksploatowanego w silnikach spalinowych zasilanych paliwami konwencjonalnymi. W przypadku silników spalinowych zasilanych wodorem olej smarowy jest szybko rozcieńczany dużą ilością wody przedostająca się do niego z procesu spalania wodoru. Ponadto możliwość jego przedostawania się do komór spalania silnika w powiązaniu z tendencją do tworzenia się osadów na powierzchniach komór spalania tworzy zagrożenie powstawania tzw. hot spots, a zatem miejsc powodujących inicjowanie nienormalnego procesu spalania.
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Fąfara, Jean-Marc, e Norbert Modliński. "Computational Fluid Dynamics (CFD) Assessment of the Internal Flue Gases Recirculation (IFGR) Applied to Gas Microturbine in the Context of More Hydrogen-Enriched Fuel Use". Energies 16, n. 18 (19 settembre 2023): 6703. http://dx.doi.org/10.3390/en16186703.
Testo completoAbstract (sommario):
Renewable energy is a promising substitute for fossil fuels when corelated with P2G technology. To optimise P2G efficiency, there is a need to increase hydrogen fraction in the fuel stream. Simultaneously gas microturbines are widely applied in many industry sectors. These devices are often equipped with diffusion combustors. This situation was investigated in this paper. The P2G and gas microturbines may be integrated together in the future leading to the application of hydrogen-enriched fuel. Hydrogen-enriched fuel causes increase in combustion temperature and velocity. In a nonadapted combustor, these phenomena could result in an increase of NOx emissions and risk of material overheating and failure. In order to adapt the combustors for hydrogen-enriched fuel, the concept of autonomous internal flue gases recirculation (IFGR) system was applied to this issue. In this paper, the IFGR system applied to gas microturbine was studied in terms of hydrogen-enriched fuel application. The obtained exhaust gases recirculation ratios were too low to affect the combustion process as it was expected. The observed combustion modifications in the combustor were hardly linked to the air flow modification in the liner, due to IFGR system implementation. After CFD studies, the proposed IFGR system does not seem to provide the expected effects.
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Naeemi, Saeed, e Seyed Abdolmehdi Hashemi. "Numerical investigations on the liftoff velocity of H2-air premixed combustion in a micro-cylindrical combustor with gradually changed section area". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, n. 17 (25 marzo 2020): 3497–508. http://dx.doi.org/10.1177/0954406220914925.
Testo completoAbstract (sommario):
Sustaining and stabilizing flames are crucial issues in micro-combustion. In some micro-electro-mechanical systems such as the micro-thermophotovoltaic system, the flame should be formed in the combustion chamber, not outside it (combustion without liftoff). So, study of the liftoff phenomenon is important and vital in these systems. The aim of this study is to evaluate effect of changing combustor section area on the critical liftoff velocity in a micro-cylindrical combustor. For this purpose, the critical liftoff velocities are numerically identified for four combustor configurations (convergent, divergent, convergent-divergent and divergent-convergent combustion chamber). Premixed mixture of hydrogen-air has been used as reactants for the current investigation. Turbulence model implemented in this paper is RNG k-epsilon and combustion reaction was modeled with 10 species and 21 steps scheme using Eddy Dissipation Concept model. Two non-dimensional numbers d1/d2 (inlet to outlet diameter ratio) and d1/d3 (inlet to throat diameter ratio) are defined. For d1/d2 > 1.0, the combustion chamber is convergent, otherwise it is divergent. When d1/d3 > 1.0, the micro combustor is convergent-divergent and for d1/d3 < 1.0, the micro combustor is divergent-convergent. The results indicate that with increasing d1/d2, the liftoff occurs in a lower inlet flow velocity. With varying d1/d3, from 0.71 (2.0/2.8) to 1.0 (2.0/2.0), the liftoff velocity is reduced. Based on the numerical results, it can be said that the use of convergent and convergent-divergent combustion chamber decreases liftoff velocity. Meanwhile, the combustor with diverging and diverging-converging structure can enhance liftoff velocity. In the same condition, critical liftoff velocity of divergent-convergent micro combustor is the highest among all cases and this configuration is appropriate for Micro Electro-Mechanical Systems that work with high inlet velocity.
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Yang, Xiao, Zhihong He, Lei Zhao, Shikui Dong e Heping Tan. "Effect of Channel Diameter on the Combustion and Thermal Behavior of a Hydrogen/Air Premixed Flame in a Swirl Micro-Combustor". Energies 12, n. 20 (10 ottobre 2019): 3821. http://dx.doi.org/10.3390/en12203821.
Testo completoAbstract (sommario):
Improving the flame stability and thermal behavior of the micro-combustor (MC) are major challenges in microscale combustion. In this paper, the micro combustions of an H2/air premixed flame in a swirl MC with various channel diameters (Din = 2, 3, 4 mm) were analyzed based on an established three-dimensional numerical model. The effects of hydrogen mass flow rate, thermal conductivity of walls, and the preferential transport of species were investigated. The results indicated that the flame type was characterized by the presence of two recirculation zones. The flame was anchored by the recirculation zones, and the anchoring location of the flame root was the starting position of the recirculation zones. The recirculation zones had a larger distribution of local equivalence ratio, especially in the proximity of the flame root, indicating the formation of a radical pool. The combustion efficiency increased with an increasing Din due to the longer residence time of the reactants. Furthermore, the MC with Din = 2 mm obtained the highest outer wall temperature distribution. However, the MC with Din = 4 mm had a better uniformity of outer wall temperature and large emitter efficiency due to the larger radiation surface. An increase in thermal conductivity boosts the thermal performance of combustion efficiency, emitter efficiency, and wall temperature uniformity. But there is a critical point of thermal conductivity that can increase the thermal performance. The above results can offer us significant guidance for designing MC with high thermal performance.
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Kanik Mittal e Sachin Srivastava. "SCRAMJET: Future High Speed Aircraft". Acceleron Aerospace Journal 3, n. 7 (30 dicembre 2024): 785. https://doi.org/10.61359/11.2106-2476.
Testo completoAbstract (sommario):
In the current era of technological advancement, the scramjet has become one of the most conventional engines for achieving supersonic speeds in aircraft. The scramjet comprises three basic components: the inlet, combustor, and nozzle. Various fuels, such as Kerosene, JP-7, JP-8, hydrocarbon-based fuels, and hydrogen, have been used in scramjets, demonstrating distinct performance characteristics. Tests have shown that hydrocarbon-fueled scramjet engines can achieve a Mach number range of 3.5 to 7, while solid-fueled scramjets have the potential to achieve combustion efficiencies of 0.7–0.9. Fuel injection and mixing techniques were applied in the combustor to enhance thrust and pressure ratios. Advanced injection methods were incorporated into the strut or walls of the combustor to improve combustion efficiency. The air intake capability of the scramjet depends on the inlet design, which should aim to minimize spillage drag and ensure adequate shock train formation. The flamelet approach has demonstrated improved combustion performance and maximized fuel efficiency through the effective placement of the flamelet. Additionally, the flamelet approach optimizes fuel mixing and injection processes within the supersonic flow. By employing a dual-mode scramjet isolator, an equivalence ratio range of 0.06–0.32 was achieved during the transition from supersonic to subsonic combustion. Combustion analysis revealed the behavior of the combustor when using jet fuels and additives. CFD data indicated that incomplete combustion releases harmful gases, such as carbon monoxide and nitrogen oxides, while complete combustion produces stable by-products like water and carbon dioxide. These issues are often attributed to inadequate air-fuel mixing or insufficient air supply. Simulations highlighted the need for improvements in combustor design to prevent thermal choking under specific conditions.
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Cameretti, Maria Cristina, Roberta De Robbio, Vincenzo Ferrara e Raffaele Tuccillo. "Performance and Emissions Evaluation of a Turbofan Burner with Hydrogen Fuel". Aerospace 12, n. 3 (12 marzo 2025): 231. https://doi.org/10.3390/aerospace12030231.
Testo completoAbstract (sommario):
This paper examines the changes in the performance level and pollutant emissions of a combustion chamber for turbofan engines. Two different fuels are compared: a conventional liquid fuel of the JET-A (kerosene) class and a hydrogen-based gaseous fuel. A turbofan engine delivering a 70 kN thrust at cruise conditions and 375 kN thrust at take-off is considered. The comparison is carried out by investigating the combustion pattern with different boundary conditions, the latter assigned along a typical flight mission. The calculations rely on a combined approach with a preliminary lumped parameter estimation of the engine performance and thermodynamic properties under different flight conditions (i.e., take-off, climbing, and cruise), and a CFD-based combustion simulation employing as boundary conditions the outputs obtained from the 0-D computations. The results are discussed in terms of performance, thermal properties, distributions throughout the combustor, and of pollutant concentration at the combustor outflow. The results demonstrate that replacing the JET-A fuel with hydrogen does not affect the overall engine performance significantly, and stable and efficient combustion takes place inside the burner, although a different temperature regime is observable causing a relevant increase in thermal NO emissions.
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Kim, Chae-Hyoung, e In-Seuck Jeung. "Forced Combustion Characteristics Related to Different Injection Locations in Unheated Supersonic Flow". Energies 12, n. 9 (8 maggio 2019): 1746. http://dx.doi.org/10.3390/en12091746.
Testo completoAbstract (sommario):
This work focuses on forced combustion with regards to the relationship between vent mixer models and several injection locations in unheated supersonic flow. A plasma jet torch was used to ignite the hydrogen-air mixture in a laboratory-scaled combustor duct. The flow field of the combustion was visualized with pressure and gas-sampling measurements. The vent mixers indicate good dispersion characteristics of the mixture for both parallel and normal 1 injections. However, forced combustion is dominantly governed by the injection rate toward the plasma jet (hot source) because the combustible region is restricted under the cold main flow. For this reason, the parallel injection, which provides the hydrogen-air mixture directly toward the plasma jet, shows good combustion performance. The normal 1 injection interacted with the vent mixers and shows slightly good combustion performance. Lastly, the normal 2 injection is little affected by the vent mixers and has poor combustion performance.
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Zian, Norhaslina Mat, Hasril Hasini e Nur Irmawati Om. "Investigation of Syngas Combustion at Variable Methane Composition in Can Combustor Using CFD". Advanced Materials Research 1016 (agosto 2014): 592–96. http://dx.doi.org/10.4028/www.scientific.net/amr.1016.592.
Testo completoAbstract (sommario):
This paper describes the analysis of the fundamental effect of synthetic gas combustion in a can-type combustor using Computational Fluid Dynamic(CFD). Emphasis is given towards the effect of variation of methane to the flame profile, temperature distribution and heat flux in the combustor. In this study, the composition of hydrogen in the syngas was fixed at 30% while methane and carbon monoxide were varied. Results show that the flame temperature and NOxemissions are highly dependent on the composition of methane in the syngas fuel. Nevertheless, the overall NOxemission for all cases is relatively lower than the conventional pure natural gas combustion.
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Beita, Jadeed, Midhat Talibi, Suresh Sadasivuni e Ramanarayanan Balachandran. "Thermoacoustic Instability Considerations for High Hydrogen Combustion in Lean Premixed Gas Turbine Combustors: A Review". Hydrogen 2, n. 1 (8 gennaio 2021): 33–57. http://dx.doi.org/10.3390/hydrogen2010003.
Testo completoAbstract (sommario):
Hydrogen is receiving increasing attention as a versatile energy vector to help accelerate the transition to a decarbonised energy future. Gas turbines will continue to play a critical role in providing grid stability and resilience in future low-carbon power systems; however, it is recognised that this role is contingent upon achieving increased thermal efficiencies and the ability to operate on carbon-neutral fuels such as hydrogen. An important consideration in the development of gas turbine combustors capable of operating with pure hydrogen or hydrogen-enriched natural gas are the significant changes in thermoacoustic instability characteristics associated with burning these fuels. This article provides a review of the effects of burning hydrogen on combustion dynamics with focus on swirl-stabilised lean-premixed combustors. Experimental and numerical evidence suggests hydrogen can have either a stabilising or destabilising impact on the dynamic state of a combustor through its influence particularly on flame structure and flame position. Other operational considerations such as the effect of elevated pressure and piloting on combustion dynamics as well as recent developments in micromix burner technology for 100% hydrogen combustion have also been discussed. The insights provided in this review will aid the development of instability mitigation strategies for high hydrogen combustion.
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Beita, Jadeed, Midhat Talibi, Suresh Sadasivuni e Ramanarayanan Balachandran. "Thermoacoustic Instability Considerations for High Hydrogen Combustion in Lean Premixed Gas Turbine Combustors: A Review". Hydrogen 2, n. 1 (8 gennaio 2021): 33–57. http://dx.doi.org/10.3390/hydrogen2010003.
Testo completoAbstract (sommario):
Hydrogen is receiving increasing attention as a versatile energy vector to help accelerate the transition to a decarbonised energy future. Gas turbines will continue to play a critical role in providing grid stability and resilience in future low-carbon power systems; however, it is recognised that this role is contingent upon achieving increased thermal efficiencies and the ability to operate on carbon-neutral fuels such as hydrogen. An important consideration in the development of gas turbine combustors capable of operating with pure hydrogen or hydrogen-enriched natural gas are the significant changes in thermoacoustic instability characteristics associated with burning these fuels. This article provides a review of the effects of burning hydrogen on combustion dynamics with focus on swirl-stabilised lean-premixed combustors. Experimental and numerical evidence suggests hydrogen can have either a stabilising or destabilising impact on the dynamic state of a combustor through its influence particularly on flame structure and flame position. Other operational considerations such as the effect of elevated pressure and piloting on combustion dynamics as well as recent developments in micromix burner technology for 100% hydrogen combustion have also been discussed. The insights provided in this review will aid the development of instability mitigation strategies for high hydrogen combustion.
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Roga, Sukanta, e Krishna Murari Pandey. "Computational Analysis of Hydrogen-Fueled Scramjet Combustor Using Cavities in Tandem Flame Holder". Applied Mechanics and Materials 772 (luglio 2015): 130–35. http://dx.doi.org/10.4028/www.scientific.net/amm.772.130.
Testo completoAbstract (sommario):
This work presents the computational analysis of scramjet combustor using cavities in tandem flame holder by means of 3D. The fuel used by scramjet combustor with cavities in tandem flame holder is hydrogen, the fluid flow and the work is based on the species transport combustion with standard k-ε viscous model. The Mach number at inlet is 2.47 and stagnation temperature and static pressure for vitiated air are 1000K and 100kPa respectively. These computational analysis is mainly aimed to study the flow structure and combustion efficiency. The computational results are compared qualitatively and quantitatively with experimental results and these are agreed as well. Due to the combustion, the recirculation region behind the cavity injector becomes larger as compared to mixing case which acts as a flame holder. From the analysis, the maximum Mach number of 2.33 is observed in the recirculation areas.
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Teodosio, Luigi, Fabio Berni, Alfredo Lanotte e Enrica Malfi. "1D/3D simulation procedure to investigate the potential of a lean burn hydrogen fuelled engine". Journal of Physics: Conference Series 2385, n. 1 (1 dicembre 2022): 012085. http://dx.doi.org/10.1088/1742-6596/2385/1/012085.
Testo completoAbstract (sommario):
Abstract In recent years hydrogen, especially the one generated by renewable energy, is gaining increasing attention as a clean fuel to support the future mobility towards efficient and low emission solutions for propulsion systems. In this scenario, the present work deals with the virtual conversion of a single-cylinder Diesel engine, conceived for marine applications, into a hydrogen Spark Ignition (SI) unit. A simulation methodology is adopted, combining 1D and 3D Computational Fluid Dynamics (CFD) methods. First, experiments are realized on the original Diesel engine mounted on a test bench, collecting main performance indicators and emissions. A complete 1D engine model (GT-Power™) is developed and validated against measurements. Then, a 3D model of the cylinder (STAR-CD) is set-up and the related combustion outcomes are compared both with 1D and experimental results, showing an overall good agreement. In the second stage, the Diesel unit is converted into a port-injected hydrogen SI engine; the 3D model is re-arranged and utilized to reproduce pre-mixed hydrogen combustions under ultra-lean air/fuel (A/F) mixtures. Also, the 1D model is partly modified and coupled to an advanced combustion sub-model integrated with fast tabulated chemical kinetics to predict the knock. In particular, 1D combustion evolution is calibrated against the results of 3D CFD hydrogen combustion simulation. Finally, the calibrated 1D model is applied to investigate the advantages of ultra-lean hydrogen combustion in terms of efficiency, NO, and unburned H2 formation at medium/high loads.
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Jeong, Seung-Min, e Jeong-Yeol Choi. "Combined Diagnostic Analysis of Dynamic Combustion Characteristics in a Scramjet Engine". Energies 13, n. 15 (4 agosto 2020): 4029. http://dx.doi.org/10.3390/en13154029.
Testo completoAbstract (sommario):
In this work, the dynamic combustion characteristics in a scramjet engine were investigated using three diagnostic data analysis methods: DMD (Dynamic Mode Decomposition), STFT (Short-Time Fourier Transform), and CEMA (Chemical Explosive Mode Analysis). The data for the analyses were obtained through a 2D numerical experiment using a DDES (Delayed Detached Eddy Simulation) turbulence model, the UCSD (University of California at San Diego) hydrogen/oxygen chemical reaction mechanism, and high-resolution schemes. The STFT was able to detect that oscillations above 50 kHz identified as dominant in FFT results were not the dominant frequencies in a channel-type combustor. In the analysis using DMD, it was confirmed that the critical point that induced a complete change of mixing characteristics existed between an injection pressure of 0.75 MPa and 1.0 MPa. A combined diagnostic analysis that included a CEMA was performed to investigate the dynamic combustion characteristics. The differences in the reaction steps forming the flame structure under each combustor condition were identified, and, through this, it was confirmed that the pressure distribution upstream of the combustor dominated the dynamic combustion characteristics of this scramjet engine. From these processes, it was confirmed that the combined analysis method used in this paper is an effective approach to diagnose the combustion characteristics of a supersonic combustor.
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Oleś, Sylwia, Jakub Mularski, Dariusz Pyka, Halina Pawlak-Kruczek e Artur Pozarlik. "Optimization of Hydrogen Supercritical Oxy-Combustion in Gas Turbines". Fuels 6, n. 1 (14 gennaio 2025): 6. https://doi.org/10.3390/fuels6010006.
Testo completoAbstract (sommario):
This study investigates the combustion of hydrogen in supercritical gas turbines, emphasizing the optimization of combustor design through computational fluid dynamics (CFD) simulations. Key parameters analysed include the number of oxygen inlets, operating pressure, excess working fluid in oxygen inlets, power output, and the use of different working fluids: supercritical argon (sAr) and supercritical xenon (sXe). The results highlight how these parameters influence temperature distribution, flame stability, and overall combustion efficiency. Findings suggest that increasing the number of oxygen inlets can significantly affect temperature profiles, while higher operating pressures lead to shorter flames. The dilution of oxygen by argon reduces the peak temperatures, and the choice of working fluid impacts cooling efficiency and flame dynamics. This study provides valuable information on optimizing the design of supercritical combustion chambers for hydrogen combustion in novel supercritical gas turbine systems.
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Wang, Taiyu, Zhenguo Wang, Zun Cai, Jian Chen, Mingbo Sun, Zeyu Dong e Bin An. "Effects of combustor geometry on the combustion process of an RBCC combustor in high-speed ejector mode". Modern Physics Letters B 33, n. 27 (30 settembre 2019): 1950330. http://dx.doi.org/10.1142/s0217984919503305.
Testo completoAbstract (sommario):
The combustion characteristics of high-speed ejector mode in a 2-dimensional strut-based RBCC (rocket-based combined cycle) combustor had been investigated numerically in a Mach 2.5 supersonic flow. The numerical approach had been validated by comparing numerical results with available experimental data. Besides, three different hydrogen-air chemical reaction mechanisms had also been compared. The effect of the combustor geometry on the combustion process was then discussed by analyzing the heat release distribution and flow field. It was found that the wall configuration, closeout angle of the converging location and converging ratio all have significant influences on the heat release distribution and flow field structures. It is demonstrated that a converging–diverging wall configuration is beneficial for the combustion process with significant heat release increase compared to the other wall configurations. In addition, the closeout angle of the converging location is also closely related to the combustion performance, and there exists an optimized closeout angle in a specific combustor geometry. It is also revealed that the major heat release region moves upstream obviously with increase in the converging ratio, leading to an enhanced combustion process. However, the converging ratio is still to be optimized to keep a balance between heat release increase and total pressure loss of the supersonic flow.
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Wang, Hongbo, Zhenguo Wang, Mingbo Sun e Haiyan Wu. "Combustion modes of hydrogen jet combustion in a cavity-based supersonic combustor". International Journal of Hydrogen Energy 38, n. 27 (settembre 2013): 12078–89. http://dx.doi.org/10.1016/j.ijhydene.2013.06.132.
Testo completo
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Suppandipillai, Jeyakumar, Jayaraman Kandasamy, R. Sivakumar, Mehmet Karaca e Karthik K. "Numerical investigations on the hydrogen jet pressure variations in a strut based scramjet combustor". Aircraft Engineering and Aerospace Technology 93, n. 4 (5 aprile 2021): 566–78. http://dx.doi.org/10.1108/aeat-08-2020-0162.
Testo completoAbstract (sommario):
Purpose This paper aims to study the influences of hydrogen jet pressure on flow features of a strut-based injector in a scramjet combustor under-reacting cases are numerically investigated in this study. Design/methodology/approach The numerical analysis is carried out using Reynolds Averaged Navier Stokes (RANS) equations with the Shear Stress Transport k-ω turbulence model in contention to comprehend the flow physics during scramjet combustion. The three major parameters such as the shock wave pattern, wall pressures and static temperature across the combustor are validated with the reported experiments. The results comply with the range, indicating the adopted simulation method can be extended for other investigations as well. The supersonic flow characteristics are determined based on the flow properties, combustion efficiency and total pressure loss. Findings The results revealed that the augmentation of hydrogen jet pressure via variation in flame features increases the static pressure in the vicinity of the strut and destabilize the normal shock wave position. Indeed, the pressure of the mainstream flow drives the shock wave toward the upstream direction. The study perceived that once the hydrogen jet pressure is reached 4 bar, the incoming flow attains a subsonic state due to the movement of normal shock wave ahead of the strut. It is noticed that the increase in hydrogen jet pressure in the supersonic flow field improves the jet penetration rate in the lateral direction of the flow and also increases the total pressure loss as compared with the baseline injection pressure condition. Practical implications The outcome of this research provides the influence of fuel injection pressure variations in the supersonic combustion phenomenon of hypersonic vehicles. Originality/value This paper substantiates the effect of increasing hydrogen jet pressure in the reacting supersonic airstream on the performance of a scramjet combustor.
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Pandey, K. M., e T. Sivasakthivel. "CFD Analysis of Mixing and Combustion of a Hydrogen Fueled Scramjet Combustor with a Strut Injector by Using Fluent Software". International Journal of Engineering and Technology 3, n. 5 (2011): 466–53. http://dx.doi.org/10.7763/ijet.2011.v3.268.
Testo completo
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Dash, Santanu Kumar, Suprava Chakraborty, Michele Roccotelli e Umesh Kumar Sahu. "Hydrogen Fuel for Future Mobility: Challenges and Future Aspects". Sustainability 14, n. 14 (6 luglio 2022): 8285. http://dx.doi.org/10.3390/su14148285.
Testo completoAbstract (sommario):
Nowadays, the combustion of fossil fuels for transportation has a major negative impact on the environment. All nations are concerned with environmental safety and the regulation of pollution, motivating researchers across the world to find an alternate transportation fuel. The transition of the transportation sector towards sustainability for environmental safety can be achieved by the manifestation and commercialization of clean hydrogen fuel. Hydrogen fuel for sustainable mobility has its own effectiveness in terms of its generation and refueling processes. As the fuel requirement of vehicles cannot be anticipated because it depends on its utilization, choosing hydrogen refueling and onboard generation can be a point of major concern. This review article describes the present status of hydrogen fuel utilization with a particular focus on the transportation industry. The advantages of onboard hydrogen generation and refueling hydrogen for internal combustion are discussed. In terms of performance, affordability, and lifetime, onboard hydrogen-generating subsystems must compete with what automobile manufacturers and consumers have seen in modern vehicles to date. In internal combustion engines, hydrogen has various benefits in terms of combustive properties, but it needs a careful engine design to avoid anomalous combustion, which is a major difficulty with hydrogen engines. Automobile makers and buyers will not invest in fuel cell technology until the technologies that make up the various components of a fuel cell automobile have advanced to acceptable levels of cost, performance, reliability, durability, and safety. Above all, a substantial advancement in the fuel cell stack is required.
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Mahjoub, Mustafa, Aleksandar Milivojevic, Vuk Adzic, Marija Zivkovic, Vasko Fotev e Miroljub Adzic. "Numerical analysis of lean premixed combustor fueled by propane-hydrogen mixture". Thermal Science 21, n. 6 Part A (2017): 2599–608. http://dx.doi.org/10.2298/tsci160717131m.
Testo completoAbstract (sommario):
A numerical investigation of combustion of propane-hydrogen mixture in a swirl premixed micro gas turbine combustor is presented. The effects of hydrogen addition into propane on temperature distribution in the combustor, reaction rates of propane and hydrogen and NOx emissions for different equivalence ratios and swirl numbers are given. The propane-hydrogen mixture of 90/10% by volume was assumed. The numerical results and measurements of NOx emissions for pure propane are compared. Excellent agreements are found for all equivalence ratios and swirl numbers, except for the highest swirl number (1.13). It is found that the addition of hydrogen into propane increases NOx emission. On the other hand, the increase of swirl number and the decrease of equivalence ratio decrease the NOx emissions.
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Medhat, Moataz, Adel Khalil e Mohamed A. Yehia. "A Numerical Study of Decarbonizing Marine Gas Turbine Emissions Through Ammonia/Hydrogen Fuel Blends". Journal of Physics: Conference Series 2304, n. 1 (1 agosto 2022): 012008. http://dx.doi.org/10.1088/1742-6596/2304/1/012008.
Testo completoAbstract (sommario):
Abstract The employment of gas turbine in combination with diesel engines and steam generators is a well-known power generation technique in modern marines and ship propulsion. Previously, it rendered its foundations in marine industry through higher power weight ratios and lower NOx emissions if compared to pure diesel engine driven marines. As climate change concerns are becoming more serious, the decarbonization of marine combustion products is becoming of environmental concern. In the present study a modified design of the burner and combustor was suggested to allow for the longer residence time required for releasing the combustion products from the ‘slow’ burning ammonia molecule. Afterwards, the more formidable challenge of relatively higher NOx emissions was treated through analysis of the effect of altering the equivalence ratio, hydrogen blending, increasing the combustor working pressure and staging the combustion. The latest tactic resulted in lowering values of exit NOx to around 30 ppmv, which is a quite promising result.
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Kim, Min-Su, In-Hoi Koo, Keon-Hyeong Lee, Eun-Sung Lee, Hyung-Seok Han, Seung-Min Jeong, Holak Kim e Jeong-Yeol Choi. "Experimental Study on the Ignition Characteristics of Scramjet Combustor with Tandem Cavities Using Micro-Pulse Detonation Engine". Aerospace 10, n. 8 (11 agosto 2023): 706. http://dx.doi.org/10.3390/aerospace10080706.
Testo completoAbstract (sommario):
This experimental investigation focused on the ignition and combustion characteristics of a tandem cavity-based scramjet combustor with side-by-side identical cavities. This study utilized the Pusan National University-direct connect scramjet combustor (PNU-DCSC), which was capable of simulating flight conditions at Mach number 4.0–5.0 and altitudes of 20–25 km using the vitiated air heater (VAH). The combustion tests were conducted under off-design point conditions corresponding to low inlet enthalpy. It is a condition in which self-ignition does not occur, and a micro pulse detonation engine (μPDE) ignitor is used. The results revealed that as the injection pressure of the gaseous hydrogen fuel (GH2) and the corresponding equivalence ratio increased, the combustion mode transitioned from the cavity-shear layer flame to the jet-wake flame. Furthermore, the measured wall static pressure profiles along the isolator and scramjet combustor indicated that the region of elevated pressure distribution caused by the shock train expanded upstream with higher equivalence ratios. When ignited from the secondary cavity, the combustion area did not extend to the primary cavity at lower equivalence ratios, while it expanded upstream faster with higher equivalence ratios. Therefore, the combustion characteristics of the tandem cavity were found to vary based on the overall equivalence ratio of the main fuel (GH2) and ignition position.
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Ciani, Andrea, Mirko Bothien, Birute Bunkute, John Wood e Gerhard Früchtel. "Superior fuel and operational flexibility of sequential combustion in Ansaldo Energia gas turbines". Journal of the Global Power and Propulsion Society 3 (21 ottobre 2019): 630–38. http://dx.doi.org/10.33737/jgpps/110717.
Testo completoAbstract (sommario):
The increasing use of renewables for energy production is also accompanied by an increasing need for flexible power production, while aiming at carbon free emissions. The potential solutions of energy storage of excess generation from renewables through hydrogen production and pre-combustion carbon capture are gaining momentum. Both scenarios require gas turbines capable of operation with hydrogen-based fuels. At the same time, the composition of natural gas considered for use within gas turbines is becoming significantly more variable due to increased use of liquefied natural gas and a wider range of gas sources and extraction methods. Fuel flexibility, both in terms of the amount of hydrogen and higher hydrocarbons is therefore of utmost importance in modern gas turbine development. This paper provides an overview of key steps taken in the design and development of an operation concept, leveraging the advantage of the GT36 Constant Pressure Sequential Combustion system (CPSC) – a premixed low emission reheat combustion technology, characterised by an extremely broad fuel range capability, composed of two combustion stages in series. The results presented in this paper clearly show that the complementarity behaviour of first and second combustion stages – extensively proven for fuels containing high concentrations of higher hydrocarbons – can be extended to hydrogen. Ultimately, this allows the achievement of ultra-low emissions at full combustor exit temperature maintaining the power and efficiency performance of F and H class engines. Recent validation performed at the high pressure combustion facility at DLR-Cologne, proved fuel flexibility with minimal or no de-rating with hydrogen contents from 0 to 50% in volume, without any modification of the standard GT36 hardware. Based on the current studies, the flexibility of the GT36 CPSC system is envisaged to enable a further increase in hydrogen content allowing this H class engine to be operated with 100% hydrogen.
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Xi, Wenxiong, Hui Xu, Tianyang Dong, Zhiyong Lin e Jian Liu. "Numerical Investigation of Combustion Mechanism with Multi-Position Injection in a Dual-Mode Combustor". Aerospace 10, n. 7 (24 luglio 2023): 656. http://dx.doi.org/10.3390/aerospace10070656.
Testo completoAbstract (sommario):
To improve the flame propagation, combustion stability, and uniformity of the temperature field, multi-position injection is applied in a dual-mode combustor by controlling heat release in different locations. Using the chemical reaction of the finite rate combustion model and the detailed reaction mechanism of hydrogen combustion as described by Jachimowski, the influence of different multi-position injection patterns in a dual-mode combustor is analyzed. The one-equation Large Eddy Simulation (LES) turbulence model was chosen to define the sublattice turbulent viscous terms in a three-dimensional scramjet model. Based on a combustion chamber, the effect of the injection equivalent ratio (0.35–0.70), the relative position of the nozzle holes, and the injection pressure on the combustion process and flow field characteristics are analyzed with multi-position injection. The combustion efficiency, total pressure recovery coefficients, and pressure distribution under different operation conditions are compared. We observed that the combustion intensity increases and the upstream combustion shock string distance becomes greater with increased equivalent ratios. When the global equivalent ratio of multi-position injection remains unchanged, the arrangement of nozzles with the small injection spacing, i.e., two injection holes arranged face to face on the upper and lower walls, or the setting of multiple injection holes with the same pressure, can effectively increase the stability rate of the combustion flow field. In addition, the combustion efficiency at the outlet and the internal pressure of the combustion chamber in the stable state are also improved, relative to the increased total pressure loss.
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Pappa, Alessio, e Ward De Paepe. "Humidification Towards Flashback Prevention in a Classical Micro Gas Turbine: Thermodynamic Performance Assessment". E3S Web of Conferences 414 (2023): 03010. http://dx.doi.org/10.1051/e3sconf/202341403010.
Testo completoAbstract (sommario):
Combustion air humidification has proven to be effective to stabilize hydrogen combustion and to avoid flashback apparition in a typical micro Gas Turbine (mGT). However, both the fuel alteration and combustion air dilution will impact the cycle performance. A complete characterization of this thermodynamic impact is essential to ensure that the mGTs become cleaner, and fully flexible to fit with the expectation of future small-scale decentralized power production. Therefore, the objective of this work is twofold: the determination of the necessary dilution for combustion stabilization, depending on the type of fuel, as well as the impact assessment on the cycle performance. In this framework, a hybrid model of the Turbec T100 mGT combustor, combining a 0D Chemical Reactor Network and 1D Laminar flame calculations, is used to first assess the flashback limits. The laminar flame speed is evaluated to predetermine the necessary minimal water dilution of the combustion air to avoid flashback for several CH4/H2 blends. Second, a thermodynamic analysis is performed to assess the impact of the flame stabilization measures on the cycle performance of the mGT using Aspen Plus. The 0D/1D simulation results show that the combustor of the Turbec T100 can operate with fuels containing up to 100% hydrogen. However, the thermodynamic analysis shows that the water dilution leads to a decreased electrical performance. Future work consists in the iterative coupling of both 0D/1D and the Aspen model to correctly predict the flashback limits, considering the altering operating conditions. To conclude, with this work, we provide a framework for future mGT operations with alternative fuels.
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Nishiguchi, Hironobu, Masatoshi Kodera e Sadatake Tomioka. "Effects of the Fuel Species on the Combustion Pressure in a Two Staged Fueled Scramjet Combustor". Aerospace 12, n. 1 (18 gennaio 2025): 66. https://doi.org/10.3390/aerospace12010066.
Testo completoAbstract (sommario):
Two-staged fuel injection configuration for scramjet combustors has been shown to be effective in distributing heat release in the combustor for preventing the unstart transition of the engine by suppressing peak pressure while increasing the pressure thrust. In this study, the effect of fuel species on combustion characteristics in a two-staged fueled scramjet combustor was investigated. Wall pressure measurements in a two-staged fueled scramjet combustor were conducted in a combustion wind tunnel facility with fuels having different reactivity, such as H2 and CH4. Reynolds-Averaged Navier–Stokes/Large Eddy Simulation (RANS/LES) hybrid simulations were performed to verify the interaction characteristics between the primary and secondary combustion zones for different fuels. The experimental results confirmed that pressure peaks at injections were clearly separated in the hydrogen case, while these interacted with each other in the methane case with a lower reactivity than H2. The RANS/LES Hybrid analysis predicted this effect of fuel reactivity on the pressure distribution, namely, the heat release delay of the first stage fuel caused the interaction with the second stage fuel heat release. The results indicate that the need to design the staged fueled combustor, i.e., the injection stage interval accordingly to the reactivity of the fuel.
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Wang, Cheng Jun, Xin Xin, Ping Jiang e Wen Zeng. "Analysis of Fuel Properties Effects on Flame Radiation in a Gas Turbine Combustor". Applied Mechanics and Materials 385-386 (agosto 2013): 196–99. http://dx.doi.org/10.4028/www.scientific.net/amm.385-386.196.
Testo completoAbstract (sommario):
The influence of fuel properties on flame radiation transfer was investigated with numerical method under certain combustor fuel-air ratio and inlet air temperature in a gas turbine combustor. The numerical results show that the fuel properties affected the fuel pulverization quality, evaporation efficiency and combustion efficiency, which caused the flame temperature and its distribution change. Meanwhile, it has an effect on the formation and concentration distribution of soot, resulting in the changes of inner flame radiation heat flux and temperature caused by flame emitting radiation. Furthermore, the gas temperature change caused by the fuel properties more but the hydrogen content effect is relatively small, has an influence on the generation of NO which caused the change of the combustion efficiency.
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V. Starov, Alexey. "Determination of the limits of stable combustion at high supersonic flow velocities in a channel". Siberian Journal of Physics 3, n. 2 (1 luglio 2008): 47–60. http://dx.doi.org/10.54362/1818-7919-2008-3-2-47-60.
Testo completoAbstract (sommario):
In this paper, analysis of existing methods application of criterial description of ignition conditions and combustion break-out for summarizing of experimental results is carried out. Experimental results are obtained at investigations of hydrogen combustion in combustor with high supersonic speed of airflow. For these conditions selection of several criterions was substantiated and they have a good agreement with new experimental results. At the same time complexity of determination of experimental physical parameters, which are included in criterions, do not allow confidently to apply them for prediction of steady-state combustion limits. Therefore further accumulation of experimental data and development of measurement methods are necessary for accurate criterions obtaining.
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Xiong, Yuefei, Jiang Qin, Kunlin Cheng, Silong Zhang e Yu Feng. "Quasi-One-Dimensional Model of Hydrocarbon-Fueled Scramjet Combustor Coupled with Regenerative Cooling". International Journal of Aerospace Engineering 2022 (8 agosto 2022): 1–14. http://dx.doi.org/10.1155/2022/9931498.
Testo completoAbstract (sommario):
In order to rapidly predict the performance of hydrocarbon-fueled regeneratively cooled scramjet engine in system design, a quasi-one-dimensional model has been developed. The model consists of a supersonic combustor model with finite-rate chemistry and a cooling channel model with real gas working medium, which are governed by two sets of ordinary differential equations separately. Additional models for wall friction, heat transfer, sonic fuel injection, and mixing efficiency are also included. The two sets of ordinary differential equations are coupled and iteratively solved. The SUNDIALS code is used since the equations for supersonic combustion flow are stiff mathematically. The cooling channel model was verified by electric heating tube tests, and the supersonic combustor model was verified by experimental results for both hydrogen and hydrocarbon-fueled scramjet combustors. Three cases were comparatively studied: (1) scramjet combustor with an isothermal wall, (2) scramjet combustor with an adiabatic wall, and (3) scramjet combustor with regenerative cooling. Results showed that the model could predict the axial distributions of flow parameters in the supersonic combustor and cooling channel. Differences on ignition delay time and combustion efficiency for the three cases were observed.
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Wang, Yuhui, Wenyou Qiao e JialingLe. "Combustion Characteristics in Rotating Detonation Engines". International Journal of Aerospace Engineering 2021 (13 marzo 2021): 1–17. http://dx.doi.org/10.1155/2021/8839967.
Testo completoAbstract (sommario):
A lot of studies on rotating detonation engines have been carried out due to the higher thermal efficiency. However, the number, rotating directions, and intensities of rotating detonation waves are changeful when the flow rate, equivalence ratio, inflow conditions, and engine schemes vary. The present experimental results showed that the combustion mode of a rotating detonation engine was influenced by the combustor scheme. The annular detonation channel had an outer diameter of 100 mm and an inner diameter of 80 mm. Air and hydrogen were injected into the combustor from 60 cylindrical orifices in a diameter of 2 mm and a circular channel with a width of 2 mm, respectively. When the air mass flow rate was increased by keeping hydrogen flow rate constant, the combustion mode varied. Deflagration and diffusive combustion, multiple counterrotating detonation waves, longitudinal pulsed detonation, and a single rotating detonation wave occurred. Both longitudinal pulsed detonation and a single rotating detonation wave occurred at different times in the same operation. They could change between each other, and the evolution direction depended on the air flow rate. The operations with a single rotating detonation wave occurred at equivalence ratios lower than 0.60, which was helpful for the engine cooling and infrared stealth. The generation mechanism of longitudinal pulsed detonation is developed.
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Ullah, Lutf, Sehrish Munsif, Long Cao, Palle Ramana Murthy, Jing-Cai Zhang e Wei-Zhen Li. "Hydrogen Co-Combustion of Aromatic Volatile Organic Compounds over Pd/Al2O3 Catalyst". Catalysts 14, n. 9 (26 agosto 2024): 563. http://dx.doi.org/10.3390/catal14090563.
Testo completoAbstract (sommario):
Catalytic combustion is an effective strategy for alleviating volatile organic compounds (VOCs), including hydrocarbons and aromatic compounds, mostly derived from the petrochemical and pharmaceutical industries. We employed Pd/Al2O3 as a catalyst for combusting aromatic VOCs via hydrogen catalytic combustion. It differs from conventional approaches that do not necessitate additional electric heating. Briefly, when hydrogen (H2) is introduced below its lower explosive limit of 4% on the Pd/Al2O3 catalyst, it completely oxidizes important aromatic VOCs like benzene, toluene, ethyl benzene, and xylene to carbon dioxide and water. The catalytic performance of the integrated system remains stable even after long-term use. Therefore, hydrogen co-combustion on the Pd/Al2O3 catalyst can provide onsite heating for a facility without needing external electric heat. The catalytic performance shows no significant dependence on the sizes of Pd nanoparticles in both fresh and spent conditions, as demonstrated by XRD, XPS, and STEM analyses. Therefore, renewable green hydrogen can effectively reduce aromatic VOC pollutants, providing a more energy-efficient alternative. Our findings suggest that this integrated process is promising for converting aromatic VOCs into carbon dioxide and water without electric heating.
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Shi, Deyong, Wenyan Song, Jingfeng Ye, Bo Tao, Yanhua Wang e Qiang Fu. "Experimental Investigation of Reacting Flow Characteristics in a Dual-Mode Scramjet Combustor". International Journal of Turbo & Jet-Engines 35, n. 4 (19 dicembre 2018): 321–30. http://dx.doi.org/10.1515/tjj-2015-0014.
Testo completoAbstract (sommario):
Abstract In this work, a hydrogen fueled dual-mode scramjet combustor was investigated experimentally. Clean and dry air was supplied to the combustor through a Mach 2 Nozzle with a total temperature of 800 K and a total pressure of 800 kPa. The high enthalpy air was provided by an electricity resistance heater. Room temperature hydrogen was injected with sonic speed from injector orifices vertically, and downstream the injector a tandem cavity flame holder was mounted. Except wall pressure profiles, velocity and temperature profiles in and at exit of the combustor were also measured using hydroxyl tagging velocimetry (HTV) and tunable diode laser absorption spectroscopy (TDLAS) respectively. Results showed that combustion occurred mainly at the bottom side of the combustor. And there were also an extreme disparity of the velocity and temperature profiles along the Y direction, i.e. the transverse direction.
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Dharavath, Malsur, P. Manna e Debasis Chakraborty. "Thermochemical exploration of hydrogen combustion in generic scramjet combustor". Aerospace Science and Technology 24, n. 1 (gennaio 2013): 264–74. http://dx.doi.org/10.1016/j.ast.2011.11.014.
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Wu, Hui, Qin Chen, Weiwei Shao, Yongliang Zhang, Yue Wang e Yunhan Xiao. "Combustion of hydrogen in an experimental trapped vortex combustor". Journal of Thermal Science 18, n. 3 (settembre 2009): 256–61. http://dx.doi.org/10.1007/s11630-009-0256-5.
Testo completo