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1
Ran, Jing Yu, Li Juan Liu, Chai Zuo Li e Li Zhang. "Numerical Study on Optimum Designing of the Air Distribution Structure of a New Cyclone Combustor". Advanced Materials Research 347-353 (ottobre 2011): 3005–14. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.3005.
Testo completoAbstract (sommario):
A new type of cyclone combustor is designed based on the traditional pulverized coal liquid slag combustor in this paper. According to the characteristics of swirl combustion and flow, numerical simulation of pulverized coal combustion in a new cyclone combustor has carried out using Realizable k-ε equation model with swirl modified to gas phase and stochastic trajectory model under Lagrange coordinate system to particle phase. Flows and combustion characteristics under different working conditions are mainly studied by changing the angles of primary and secondary air inlets, and then structural characteristics of the combustor are analyzed. Results show that structural characteristics of the primary and secondary air have great influence on internal flow and combustion characteristics of the combustor. When the pitch angle, the rotation angle of the secondary air and the expansion angle of the primary air respectively are 20°, 51° and 60°, the combustion efficiency of the combustor can reach up to 98.1% and it is conducive to high-temperature liquid slagging. It is also helpful to prevented pulverized coal depositing and accumulating near the wall and then plugging the combusting channel during the starting stage in low temperature region.
2
Li, Shou-Zhe, Yu-Long Niu, Shu-Li Cao, Jiao Zhang, Jialiang Zhang e Xuechen Li. "The effect of plasma discharge on methane diffusion combustion in air assisted by an atmospheric pressure microwave plasma torch". Journal of Physics D: Applied Physics 55, n. 23 (11 marzo 2022): 235203. http://dx.doi.org/10.1088/1361-6463/ac50cb.
Testo completoAbstract (sommario):
Abstract An atmospheric pressure air microwave plasma torch is employed to assist methane diffusion combustions using a combination of a combustor and burner. Experimentally, the effect of the air microwave plasma on combustion is investigated with respect to the flame morphology and the variation of gas components in the exhaust with the fuel equivalence ratio φ or the methane flow rate by comparing plasma-assisted combustion (PAC) and natural combustion (NC) without plasma application. The combustion degree of CH4 in PACs is found to be much enhanced in rich fuel combustion than in NC in both types of burners, which is measured by Fourier transformation infrared spectrometer (FTIR). In PACs, with the use of an air microwave plasma torch, the radicals originating from excitation, ionization, and dissociation of N2 and O2 and the high gas temperature induced in the plasma discharge play an important role in assisting the combustion.
3
Yang, Xiaojian, e Guoming G. Zhu. "A control-oriented hybrid combustion model of a homogeneous charge compression ignition capable spark ignition engine". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 226, n. 10 (31 maggio 2012): 1380–95. http://dx.doi.org/10.1177/0954407012443334.
Testo completoAbstract (sommario):
To implement the homogeneous charge compression ignition combustion mode in a spark ignition engine, it is necessary to have smooth mode transition between the spark ignition and homogeneous charge compression ignition combustions. The spark ignition–homogeneous charge compression ignition hybrid combustion mode modeled in this paper describes the combustion mode that starts with the spark ignition combustion and ends with the homogeneous charge compression ignition combustion. The main motivation of studying the hybrid combustion mode is that the percentage of the homogeneous charge compression ignition combustion is a good parameter for combustion mode transition control when the hybrid combustion mode is used during the transition. This paper presents a control oriented model of the spark ignition–homogeneous charge compression ignition hybrid combustion mode, where the spark ignition combustion phase is modeled under the two-zone assumption and the homogeneous charge compression ignition combustion phase under the one-zone assumption. Note that the spark ignition and homogeneous charge compression ignition combustions are special cases in this combustion model. The developed model is capable of simulating engine combustion over the entire operating range, and it was implemented in a real-time hardware-in-the-loop simulation environment. The simulation results were compared with those of the corresponding GT-Power model, and good correlations were found for both spark ignition and homogeneous charge compression ignition combustions.
4
Ozawa, Y., J. Hirano, M. Sato, M. Saiga e S. Watanabe. "Test Results of Low NOx Catalytic Combustors for Gas Turbines". Journal of Engineering for Gas Turbines and Power 116, n. 3 (1 luglio 1994): 511–16. http://dx.doi.org/10.1115/1.2906849.
Testo completoAbstract (sommario):
Catalytic combustion is an ultralow NOx combustion method, so it is expected that this method will be applied to a gas turbine combustor. However, it is difficult to develop a catalytic combustor because catalytic reliability at high temperature is still insufficient. To overcome this difficulty, we designed a catalytic combustor in which premixed combustion was combined. By this device, it is possible to obtain combustion gas at a combustion temperature of 1300°C while keeping the catalytic temperature below 1000°C. After performing preliminary tests using LPG, we designed two types of combustor for natural gas with a capacity equivalent to one combustor used in a 20 MW class multican-type gas turbine. Combustion tests were conducted at atmospheric pressure using natural gas. As a result, it was confirmed that a combustor in which catalytic combustor segments were arranged alternately with premixing nozzles could achieve low NOx and high combustion efficiency in the range from 1000°C to 1300°C of the combustor exit gas temperature.
5
Li, Chaolong, Zhixun Xia, Likun Ma, Xiang Zhao e Binbin Chen. "Numerical Study on the Solid Fuel Rocket Scramjet Combustor with Cavity". Energies 12, n. 7 (31 marzo 2019): 1235. http://dx.doi.org/10.3390/en12071235.
Testo completoAbstract (sommario):
Scramjet based on solid propellant is a good supplement for the power device of future hypersonic vehicles. A new scramjet combustor configuration using solid fuel, namely, the solid fuel rocket scramjet (SFRSCRJ) combustor is proposed. The numerical study was conducted to simulate a flight environment of Mach 6 at a 25 km altitude. Three-dimensional Reynolds-averaged Navier–Stokes equations coupled with shear stress transport (SST) k − ω turbulence model are used to analyze the effects of the cavity and its position on the combustor. The feasibility of the SFRSCRJ combustor with cavity is demonstrated based on the validation of the numerical method. Results show that the scramjet combustor configuration with a backward-facing step can resist high pressure generated by the combustion in the supersonic combustor. The total combustion efficiency of the SFRSCRJ combustor mainly depends on the combustion of particles in the fuel-rich gas. A proper combustion organization can promote particle combustion and improve the total combustion efficiency. Among the four configurations considered, the combustion efficiency of the mid-cavity configuration is the highest, up to about 70%. Therefore, the cavity can effectively increase the combustion efficiency of the SFRSCRJ combustor.
6
Kinoshita, Y., J. Kitajima, Y. Seki e A. Tatara. "Experimental Studies on Methane-Fuel Laboratory Scale Ram Combustor". Journal of Engineering for Gas Turbines and Power 117, n. 3 (1 luglio 1995): 394–400. http://dx.doi.org/10.1115/1.2814108.
Testo completoAbstract (sommario):
The laboratory scale ram combustor test program has been investigating fundamental combustion characteristics of a ram combustor, which operates from Mach 2.5 to 5 for the super/hypersonic transport propulsion system. In our previous study, combustion efficiency had been found poor, less than 70 percent, due to a low inlet air temperature and a high velocity at Mach 3 condition. To improve the low combustion efficiency, a fuel zoning combustion concept was investigated by using a subscale combustor model first. Combustion efficiency more than 90 percent was achieved and the concept was found very effective. Then a laboratory scale ram combustor was fabricated and combustion tests were carried out mainly at the simulated condition of Mach 5. A vitiation technique was used to simulate a high temperature of 1263 K. The test results indicate that ignition, flame stability, and combustion efficiency were not significant, but the NOx emissions are a critical problem for the ram combustor at Mach 5 condition.
7
Chein, Reiyu, Yen-Cho Chen, Jui-Yu Chen e J. N. Chung. "Premixed Methanol–Air Combustion Characteristics in a Mini-scale Catalytic Combustor". International Journal of Chemical Reactor Engineering 14, n. 1 (1 febbraio 2016): 383–93. http://dx.doi.org/10.1515/ijcre-2014-0061.
Testo completoAbstract (sommario):
AbstractMethanol catalytic combustion in a mini-scale tubular quartz-made combustor is investigated in this study. An alumina sphere was employed as the support for the platinum catalyst. The experimental results showed that the combustion can be self-ignited at room temperature. Using the combustor wall temperature to characterize the combustor performance, it was found that the combustion temperature can reach a high value within a short time. The experimental results indicated that the combustor performance depends greatly on the fuel/air supply. A higher temperature can be obtained with a higher fuel/air flow rate. The insulated and non-insulated combustor experimental results indicated that heat loss to the environment is an important factor in governing the combustion characteristics due to the large surface/volume ratio. A higher temperature can also be obtained when the combustor is insulated. Because most of the combustion took place at the combustor entrance region, the experimental result suggested that the combustor length can be shortened, leading to a more compact design allowing the combustor integration with various applications. A simple numerical model was built to provide a greater understanding of the combustion characteristics and examine the heat loss effect on combustor performance.
8
Ding, Shibin, Qingzhi Wang e Weizhuo Hua. "Study on Plasma Combustion in Aeroengine Combustor". Journal of Physics: Conference Series 2483, n. 1 (1 maggio 2023): 012054. http://dx.doi.org/10.1088/1742-6596/2483/1/012054.
Testo completoAbstract (sommario):
Abstract To explore the plasma combustion affect the performance of the aircraft engine combustor, 16 components in the aviation kerosene 25-step reaction mechanism on the basis of considering step 9 simplify the plasma reaction mechanism, set up considering plasma electron collision reaction excited state relaxation and excited states participate in the process of chemical reaction kerosene combustion reaction model, The numerical calculation of the combustion process in the combustor is carried out, and the numerical calculation results of the combustion process with or without plasma combustion are compared and analyzed. The results show that the core reaction zone of the combustion chamber fuel is relatively forward under the conventional mechanism condition, and the average temperature of the combustion chamber outlet is 1910K. The temperature and high-temperature zone of the combustor where the plasma mechanism is applied are mainly distributed in the combustor outlet, mixing hole and main combustion hole, and the average temperature is 2050K. Meanwhile, the kerosene combustion efficiency also increases from 82.4% to 90.1%, increasing by about 7.7%. The results show that the addition of a plasma mechanism can deepen the chemical reaction degree of kerosene and release more heat to improve the combustion efficiency of kerosene.
9
Sing Mei, Sim, Aslina Anjang Ab Rahman, Mohd Shukur Zainol Abidin e Nurul Musfirah Mazlan. "d2 Law and Penetration Length of Jatropha and Camelina Bio-Synthetic Paraffinic Kerosene Spray Characteristics at Take-Off, Top of Climb and Cruise". Aerospace 8, n. 9 (4 settembre 2021): 249. http://dx.doi.org/10.3390/aerospace8090249.
Testo completoAbstract (sommario):
A comparison of d2 law and penetration length of biofuels with Jet–A through the incorporation of fuel properties and actual combustor inlet data at various flight trajectories is presented. This study aims to identify fuel properties and flight operating conditions that most influence droplet characteristics accurately. The study comprises two phases involving a simulation using GSP to predict combustor inlet data for the respective flight operating conditions and a simulation using ANSYS Fluent V18.1 to obtain combustion characteristics of biofuels and Jet–A. The biofuels chosen in this study are Jatropha Bio-synthetic Paraffinic Kerosene (JSPK) and Camelina Bio-synthetic Paraffinic Kerosene (CSPK), evaluated as pure (100%) and blend (50%) with Jet–A. Thrust specific fuel consumption (TSFC) of biofuels is improved due to lower fuel consumed by the engine. The d2 law curve shows a heat-up period that takes place at the early stage of the combustion process. The penetration length of the fuels is shorter at take-off. Combusting biofuels reduce combustion temperature and the penetration length of the droplet.
10
Erdiwansyah, Mahidin, Husni Husin, Nasaruddin, Muhtadin, Muhammad Faisal, Asri Gani, Usman e Rizalman Mamat. "Combustion Efficiency in a Fluidized-Bed Combustor with a Modified Perforated Plate for Air Distribution". Processes 9, n. 9 (24 agosto 2021): 1489. http://dx.doi.org/10.3390/pr9091489.
Testo completoAbstract (sommario):
Combustion efficiency is one of the most important parameters especially in the fluidized-bed combustor. Investigations into the efficiency of combustion in fluidized-bed combustor fuels using solid biomass waste fuels in recent years are increasingly in demand by researchers around the world. Specifically, this study aims to calculate the combustion efficiency in the fluidized-bed combustor. Combustion efficiency is calculated based on combustion results from the modification of hollow plates in the fluidized-bed combustor. The modified hollow plate aims to control combustion so that the fuel incorporated can burn out and not saturate. The combustion experiments were tested using palm oil biomass solid waste fuels such as palm kernel shell, oil palm midrib, and empty fruit bunches. The results of the measurements showed that the maximum combustion temperature for the palm kernel shell fuel reached 863 °C for M1 and 887 °C for M2. The maximum combustion temperature measurements for M1 and M2 from the oil palm midrib fuel testing reached 898 °C and 858 °C, respectively, while the maximum combustion temperature for M1 and M2 from the empty fruit bunches fuel was 667 °C and M2 847 °C, respectively. The rate of combustion efficiency with the modification of the hole plate in the fluidized-bed combustor reached 96.2%. Thermal efficiency in fluidized-bed combustors for oil palm midrib was 72.62%, for PKS was 70.03%, and for empty fruit bunches was 52.43%. The highest heat transfer rates for the oil palm midrib fuel reached 7792.36 W/m2, palm kernel shell 7167.38 W/m2, and empty fruit bunches 5127.83 W/m2. Thus, the modification of the holed plate in the fluidized-bed combustor chamber showed better performance of the plate than without modification.
11
PRISACARIU, Vasile, e Alexandru TUDOSIE. "CONSIDERATIONS REGARDING JET ENGINE COMBUSTOR PARAMETERS". Review of the Air Force Academy XX, n. 1 (22 dicembre 2022): 53–63. http://dx.doi.org/10.19062/1842-9238.2022.20.1.6.
Testo completoAbstract (sommario):
The thermo-gas dynamics of fuel combustion in the combustor of aircraft engines involves thermochemical activity and combustion dynamics, but also the geometric volume of the combustion process. Research around the topic provides clues regarding the fluctuations of the combustor’s performance depending on the fuels used and the kinetics of the gas mixture determined by the internal geometry of the combustor, clues that can help initiate numerical approaches regarding the optimization of the mixture and combustion temperatures. The article proposes an approach to the combustion process in jet engines both from the perspective of the fuels used and from the perspective of combustion thermo-gas dynamics through numerical analyzes designed to highlight the relevant parameters and performances of the jet engine combustor.
12
Lee, Dae Hoon, Dae-Eun Park, Euisik Yoon e Sejin Kwon. "A MEMS Piston-Cylinder Device Actuated by Combustion". Journal of Heat Transfer 125, n. 3 (20 maggio 2003): 487–93. http://dx.doi.org/10.1115/1.1565095.
Testo completoAbstract (sommario):
Combustion measurement in a cylindrical micro combustor, the construction procedure and test run of a MEMS reciprocating device are described. The sizing of the MEMS device was based on the findings of combustion measurements. Thermodynamic analysis of the pressure measurement resulted in available work up to 2.4 Joules in a combustor height of 2 mm and more with combustion efficiency of 0.6∼0.7. With combustor height less than 2 mm, combustion was incomplete due to excessive heat loss to the wall. In order to achieve the chamber height imposed by the combustion measurement, a fabrication process and wafer material that allow deeper etching was used.
13
Liu, C. H., R. M. Perez-Ortiz e J. H. Whitelaw. "Vaporizer Performance". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 206, n. 4 (luglio 1992): 265–73. http://dx.doi.org/10.1243/pime_proc_1992_206_126_02.
Testo completoAbstract (sommario):
Measured values of fuel droplet velocity, size and flux are presented for a vaporizer based on a T-shaped duct with upstream atomization by a single axial jet and by six radial jets. They were obtained for a practical range of kerosene and air flowrates and inlet air temperatures with the vaporizer in free air and in a sector of an annular combustor with combustion. Phase Doppler velocimetry was used to measure droplet velocity and size distributions and was complemented by photographic visualization of the flames within the combustor. The results obtained outside the combustor, and without combustion, showed that the Sauter mean diameter of the droplets ranged from 20 to 60 μm and the liquid-fuel flux from 0.2 to 30 per cent of the total fuel as the inlet air temperature was increased from that of ground-idle to that of full power. The droplet size and liquid-fuel flux also diminished with an increase in air flowrate, and an arrangement of six radial jets resulted in better atomization than an axial arrangement. The corresponding fluxes with combustion were in the range between 0.1 and 8 per cent as a consequence of heat transfer from combusting gases to the vaporizer tubes. Experience with the vaporizer operating within the combustor at fuel flowrates and inlet air temperatures representative of take-off showed that the vaporizer performance could deteriorate rapidly due to the formation of carbon deposits, particularly in the region where the flow impinged on the cross tube. The deposits led to reduced heat transfer and vaporization with a consequently larger proportion of larger droplets and a tendency for the region of intense combustion to move downstream.
14
Cheng, Zhe, Wen Jun Wang, Wen Qing Shen, Ai Wu Fan e Wei Liu. "Flame Stability of Methane/Air Mixture in a Heat-Recirculating-Type Mesoscale Channel with a Bluff-Body". Applied Mechanics and Materials 325-326 (giugno 2013): 12–15. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.12.
Testo completoAbstract (sommario):
To extend the stable combustion range of micro-combustor, a heat-recirculating-type planar micro-combustor fitted with a bluff-body was proposed in the present work. Numerical simulation on CH4/air premixed combustion in this combustor was performed and the stable combustion range was determined, which showed that the blow-off limit increases with the equivalence ratio and the lower flammability limit was extended. Effect of the equivalence ratio and inlet velocity on combustion efficiency and maximum temperature were investigated. The numerical results showed that combustion efficiencies were higher than 99%, and the maximum temperatures were larger than the corresponding adiabatic flame temperature due to the excess enthalpy combustion effect. However, flashback emerged when the inlet velocity was too small and the equivalence ratio is relatively high.
15
Zhang, Qun, Hua Sheng Xu, Tao Gui, Shun Li Sun, Yue Wu e Dong Bo Yan. "Investigation on Reaction Flow Field of Low Emission TAPS Combustors". Applied Mechanics and Materials 694 (novembre 2014): 45–48. http://dx.doi.org/10.4028/www.scientific.net/amm.694.45.
Testo completoAbstract (sommario):
A twin annular premixing swirler (TAPS) combustor model of low emissions was developed in this study. And computational studies on combustion process in the combustor model were carried out. Standard k-ε Turbulence Model, PDF non-premixed combustion model, Zeldovich thermal NOx formation model and DPM two-phase model were employed. The distributions of some key performance parameters such as gas temperature, flow velocity, concentrations of NOx and CO emissions were obtained and analyzed. At the same time, combustion mechanics inside the TAPS combustor model were investigated. The computational results indicated that the TAPS combustor employed in this study does a better job of improving key combustion performances such as combustion efficiency, total pressure recovery and outlet temperature distribution factor, and reducing NOx and CO emissions at the same time.
16
Cowell, L. H., R. T. LeCren e C. E. Tenbrook. "Two-Stage Slagging Combustor Design for a Coal-Fueled Industrial Gas Turbine". Journal of Engineering for Gas Turbines and Power 114, n. 2 (1 aprile 1992): 359–66. http://dx.doi.org/10.1115/1.2906599.
Testo completoAbstract (sommario):
A full-size combustor for a coal-fueled industrial gas turbine engine has been designed and fabricated. The design is based on extensive work completed through one-tenth scale combustion tests. Testing of the combustion hardware will be completed with a high pressure air supply in a combustion test facility before the components are integrated with the gas turbine engine. The combustor is a two-staged, rich-lean design. Fuel and air are introduced in the primary combustion zone where the combustion process is initiated. The primary zone operates in a slagging mode inertially removing coal ash from the gas stream. Four injectors designed for coal water mixture (CWM) atomization are used to introduce the fuel and primary air. In the secondary combustion zone, additional air is injected to complete the combustion process at fuel lean conditions. The secondary zone also serves to reduce the gas temperatures exiting the combustor. Between the primary and secondary zones is a Particulate Rejection Impact Separator (PRIS). In this device much of the coal ash that passes from the primary zone is inertially separated from the gas stream. The two-staged combustor along with the PRIS have been designated as the combustor island. All of the combustor island components are refractory-lined to minimize heat loss. Fabrication of the combustor has been completed. The PRIS is still under construction. The combustor hardware is being installed at the Caterpillar Technical Center for high pressure test evaluation. The design, test installation, and test plan of the full-size combustor island are discussed.
17
Anand, M. S., e F. C. Gouldin. "Combustion Efficiency of a Premixed Continuous Flow Combustor". Journal of Engineering for Gas Turbines and Power 107, n. 3 (1 luglio 1985): 695–705. http://dx.doi.org/10.1115/1.3239791.
Testo completoAbstract (sommario):
Experimental data in the form of radial profiles of mean temperature, gas composition and velocity at the combustor exit and combustion efficiency are reported and discussed for a swirling flow, continuous combustor. The combustor is composed of two confined, concentric independently swirling jets: an outer, annular air jet and a central premixed fuel-air jet, the fuel being propane or methane. Combustion is stabilized by a swirl-generated central recirculation zone. The primary objective of this research is to determine the effect of fuel substitution and of changes in outer flow swirl conditions on combustor performance. Results are very similar for both methane and propane. Changes in outer flow swirl cause significant changes in exit profiles, but, surprisingly, combustion efficiency is relatively unchanged. A combustion mechanism is proposed which qualitatively explains the results and identifies important flow characteristics and physical processes determining combustion efficiency. It is hypothesized that combustion occurs in a thin sheet, similar in structure to a premixed turbulent flame, anchored on the combustor centerline just upstream of the recirculation zone and swept downstream with the flow. Combustion efficiency depends on the extent of the radial propagation, across mean flow streamtubes, of this reaction sheet. It is concluded that, in general, this propagation and hence efficiency are extremely sensitive to flow conditions.
18
Evita Leninda Fahriza Ayuni, Andinusa Rahmandhika, Daryono, Ardi Lesmawanto, Krisna Bayu Rizkyawan, Ali Mokhtar e Achmad Fauzan Hery Soegiharto. "The Effect of Insulation Thickness on Heat Transfer Characteristics and Flammability in Tube Mesoscale Combustors". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 116, n. 2 (4 maggio 2024): 157–71. http://dx.doi.org/10.37934/arfmts.116.2.157171.
Testo completoAbstract (sommario):
Micropower generator is a micro-scale energy source that has two main components, namely a micro/mesoscale combustor and thermophotovoltaics (TPV). The micro-scale combustor is one part that functions as a combustion chamber that produces heat in micropower plants. Heptane is used as fuel, while the combustor combustion chamber with a diameter of 3.5 mm is made from duraluminium-quart glass tube. Combustion stability in the combustion chamber is influenced by several factors, such as temperature, geometry, and combustion chamber design. In order to maintain flame stability, mesh is added to the combustion chamber. One way to minimize heat loss in the combustion chamber is to add an insulating layer to the combustion chamber. This research aims to prove the role of adding an insulating layer in flame stability in mesoscale burners. It is necessary to add an appropriate insulating layer to minimize heat loss so that it remains stable in the mesoscale burner. This experimental test shows that the temperature distribution when adding an insulation layer with a thickness of 3 mm has a higher temperature on the outside compared to a thickness of 6 mm. Meanwhile, the temperature inside the combustor chamber with a thickness of 6 mm is superior to that with a thickness of 3 mm. The flame limit of the combustor with a mesh distance of 5 mm for liquid heptane fuel was successfully stable at an equivalent ratio of ɸ0.97 – 1.5 with a maximum speed of 31.7.
19
Hwang, Won-Sub, Bu-Kyeng Sung, Woojoo Han, Kang Y. Huh, Bok Jik Lee, Hee Sun Han, Chae Hoon Sohn e Jeong-Yeol Choi. "Real-Gas-Flamelet-Model-Based Numerical Simulation and Combustion Instability Analysis of a GH2/LOX Rocket Combustor with Multiple Injectors". Energies 14, n. 2 (13 gennaio 2021): 419. http://dx.doi.org/10.3390/en14020419.
Testo completoAbstract (sommario):
A large eddy simulation (LES) and combustion instability analysis are performed using OpenFOAM for the multiple shear-coaxial injector combustor DLR-BKD (in German Deutsches Zentrum für Luft–Brennkammer D, German Aerospace Center–Combustion Chamber D), which is a laboratory-scale combustor operating in a real-gas environment. The Redlich–Kwong–Peng–Robinson equation of state and steady-laminar flamelet model are adopted in the simulation to accurately capture the real-gas combustion effects. Moreover, the stable combustion under the LP4 condition is numerically analyzed, and the characteristics of the combustion flow field are investigated. In the numerical simulation of the combustion instability, the instability is generated by artificially superimposing the 1st transverse standing wave solution on the stable combustion solution. To decompose the combustion instability mode, the dynamic mode decomposition method is applied. Several combustion instability modes are qualitatively and quantitatively identified through contour plots and graphs, and the sustenance process of the limit cycle is investigated.
20
Qian, Yu Fen, Yan Ying Xu e Ti Hai Xu. "Combustion Characteristics of a Helmholtz-Type Valveless Self-Excited Pulse Combustor". Applied Mechanics and Materials 291-294 (febbraio 2013): 1719–22. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.1719.
Testo completoAbstract (sommario):
Combustion characteristics of a Helmholtz-type valveless self-excited pulse combustor with continuous supply of gas and air were studied. The physical and mathematical models are established based on the actual pulse combustor, and the combustion characteristics are simulated with CFD. The results show that the possible re-ignition sources for the pulse combustion may be three. The first source may be the hot remnant gas near gas/air mixture. The second re-ignition source may be the high-temperature combustion chamber wall. The third ignition source is the unburned mixture. The pressure, temperature and mass fraction of propane in the combustion chamber have the phase relations and the combustion process stimulates the acoustic oscillation.
21
Yang, Yao, Gaofeng Wang, Yuanqi Fang, YIfan Xia e Liang Zhong. "IMAGING DIAGNOSTICS OF COMBUSTION INSTABILITY IN PREMIXED SWIRLING COMBUSTION". Journal of the Global Power and Propulsion Society 4 (22 maggio 2020): 80–93. http://dx.doi.org/10.33737/jgpps/120536.
Testo completoAbstract (sommario):
An experimental study on combustion instability is presented with focus on propane-air premixed swirling flames. Swirling flames under self-excited oscillation are studied by imaging of visible light and OH* chemiluminescence filter under several typical conditions. The dynamical characteristics of swirling flames were analysed by Dynamic Mode Decomposition (DMD) method. Three types of unstable modes in the combustor system were observed, which correspond to typical acoustic resonant modes (LF mode, C1/4 mode and P1/2 mode) of the combustor system. The combustion instability is in the longitudinal mode. Furthermore, the structure of downstream hot burnt gas under stable combustion and unstable combustion is studied by imaging of visible light and near-infrared light. Results show that there is a significant difference in the downstream flow under stable combustion and unstable combustion. The DMD spectrum of the flame and the downstream hot burnt gas obtained is the same, which is close to the characteristic frequency of acoustic pressure captured by the microphone signal. The visible light and near-infrared light imaging observation method adopted in this paper provides a new imaging method for the investigation of thermo-acoustic instability.
22
Liu, Aiguo, Ruiyang Fan, Qiaochu Liu, Lei Xi e Wen Zeng. "Numerical and Experimental Study on Combustion Characteristics of Micro-Gas Turbine Biogas Combustor". Energies 15, n. 21 (7 novembre 2022): 8302. http://dx.doi.org/10.3390/en15218302.
Testo completoAbstract (sommario):
The use of biogas in land-based gas turbines for power generation is a promising approach to reducing greenhouse gases and our dependence on fossil fuels. The focus of this research was to investigate the fuel/air mixing and combustion performance in an DLE (dry low emission) type can combustor designed for a micro-gas turbine. The fuel and air mixing uniformity was studied considering the air flow characteristic and fuel injection performance through the numerical simulation. The influence of the fuel/air mixing characteristics on the combustion characteristics was studied by numerical simulation and experimental tests. The combustion characteristics studied included the temperature field in the combustor, the pattern factor at the combustor outlet, combustion efficiency, and pollutant emission characteristics. The results show the position of the fuel nozzle has little effect on the mixing uniformity due to the limited mixing space for the micro-gas turbine combustor, while there are optimal fuel nozzle diameters to generate the suitable fuel jet momentum for the mixing process. The fuel/air mixing characteristics had an obvious influence on the combustion performance for the studied DLE combustor. The increase in the fuel air mixing uniformity can decrease the NOx emissions and generate a better temperature distribution at the combustor outlet. The increased mixing uniformity may decrease the combustion efficiency and increase the CO emissions of the micro-gas turbine combustor.
23
Cao, H. L., J. N. Zhao, K. Zhang, D. B. Wang e X. L. Wei. "Diffusion Combustion Characteristics of H2/Air in the Micro Porous Media Combustor". Advanced Materials Research 455-456 (gennaio 2012): 413–18. http://dx.doi.org/10.4028/www.scientific.net/amr.455-456.413.
Testo completoAbstract (sommario):
In order to improve thermal to-electric energy conversion efficiency of the micro gas turbine power generation system, a novel micro porous media combustor is designed and experimental investigation on the H2/air diffusion combustion is performed to obtain its combustion characteristics. High efficiency diffusion combustion of H2/air can be stabilized in the very wide operating range, especially at higher excess air ratio. Exhaust gas temperature is markedly improved and meanwhile heat loss ratio is evidently decreased. Moreover, in the certain operating ranges, the greater the combustion thermal power and excess air ratio, the smaller heat loss of the micro combustor will be. The micro porous media combustor should be a preferred micro combustor for developing the micro gas turbine power generation system.
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Seume, J. R., N. Vortmeyer, W. Krause, J. Hermann, C. C. Hantschk, P. Zangl, S. Gleis, D. Vortmeyer e A. Orthmann. "Application of Active Combustion Instability Control to a Heavy Duty Gas Turbine". Journal of Engineering for Gas Turbines and Power 120, n. 4 (1 ottobre 1998): 721–26. http://dx.doi.org/10.1115/1.2818459.
Testo completoAbstract (sommario):
During the prototype shop tests, the Model V84.3A ring combustor gas turbine unexpectedly exhibited a noticeable “humming” caused by self-excited flame vibrations in the combustion chamber for certain operating conditions. The amplitudes of the pressure fluctuations in the combustor were unusually high when compared to the previous experience with silo combustor machines. As part of the optimization program, the humming was investigated and analyzed. To date, combustion instabilities in real, complex combustors cannot be predicted analytically during the design phase. Therefore, and as a preventive measure against future surprises by “humming,” a feedback system was developed which counteracts combustion instabilities by modulation of the fuel flow rate with rapid valves (active instability control, AIC). The AIC achieved a reduction of combustion-induced pressure amplitudes by 86 percent. The Combustion instability in the Model V84.3A gas turbine was eliminated by changes of the combustor design. Therefore, the AIC is not required for the operation of customer gas turbines.
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Som, S. K., e N. Y. Sharma. "Energy and Exergy Balance in the Process of Spray Combustion in a Gas Turbine Combustor". Journal of Heat Transfer 124, n. 5 (11 settembre 2002): 828–36. http://dx.doi.org/10.1115/1.1484393.
Testo completoAbstract (sommario):
A theoretical model of exergy balance based on availability transfer and flow availability in the process of spray combustion in a gas turbine combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions, for fuels with different volatilities. The velocity, temperature and concentration fields in the combustor, required for the evaluation of the flow availabilities and process irreversibilities, have been computed numerically from a two phase separated flow model of spray combustion. The total thermodynamic irreversibility in the process of spray combustion has been determined from the difference in the flow availability at inlet and outlet of the combustor. The irreversibility caused by the gas phase processes in the combustor has been obtained from the entropy transport equation, while that due to the inter-phase transport processes has been obtained as a difference of gas phase irreversibilities from the total irreversibility. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions for fuels with different volatilities has been made to throw light on the trade off between the effectiveness of combustion and the lost work in the process of spray combustion in a gas turbine combustor.
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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.
27
Wang, Fei, Xueming Li, Shuai Feng e Yunfei Yan. "Influence of Porous Media Aperture Arrangement on CH4/Air Combustion Characteristics in Micro Combustor". Processes 9, n. 10 (29 settembre 2021): 1747. http://dx.doi.org/10.3390/pr9101747.
Testo completoAbstract (sommario):
Micro-electro-mechanical systems (MEMS) occupy an important position in the national economy and military fields, and have attracted great attention from a large number of scholars. As an important part of the micro-electromechanical system, the micro-combustor has serious heat loss due to its small size, unstable combustion and low combustion efficiency. Aiming at enhancing the heat transfer of the micro-combustor, improving the combustion stability and high-efficiency combustion, this paper embedded porous media in the combustor, and the effects of different parameters on the combustion characteristics were numerically studied. The research results showed that the layout of porous media should be reasonable, and the small and large pore porous media embedded in the inner and outer layers, respectively, can bring better combustion performance. Meanwhile, A: 10–30 has a high and uniform temperature distribution, and its methane conversion rate reached 97.4%. However, the diameter ratio of the inner layer to the outer layer (d/D) of the porous medium should be maintained at 0.4–0.6, which brings a longer gas residence time, and further enables the pre-mixed gas to preheat and burn completely. At a d/D of 0.5, the combustor has the highest outer wall temperature and CH4 conversion efficiency. Besides, compared with the pore size increasing rate of Δn = 10 PPI and Δn = 10 PPI, the radial temperature distribution of the Δn = 10 PPI combustor is more uniform, meanwhile avoids the occurrence of local high temperature. Under the condition of Δn = 10 PPI, A: 20–30 layout maintains excellent thermal and combustion performance. In addition, the lean flammable limits of MC-U20, MC-10/30-0.8, and MC-20/30-0.5 were compared, at an inlet velocity of 0.5 m/s, the corresponding lean flammable limits are 0.5, 0.4, and 0.3, respectively, among them MC-20/30-0.5 has a wider flammable limit range, showing excellent combustion stability. This research has guiding significance for the combustion stability of the micro combustor.
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Najib Aminu Ismail, Mazlan Abdul Wahid, Aminuddin Sa'at, Abubakar Shitu e Mohammed Bashir Abdulrahman. "Effect of Recirculation Ratio on the Combustion Characteristics of an Asymmetric Swirling Flameless Combustor using Biogas". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 108, n. 1 (7 settembre 2023): 52–65. http://dx.doi.org/10.37934/arfmts.108.1.5265.
Testo completoAbstract (sommario):
This study investigates the influence of recirculation ratio on the combustion characteristics of an asymmetric swirling flameless combustor. The recirculation ratio, defined as the ratio of the total recirculation mass flow rate to the primary air mass flow rate, plays a crucial role in determining the performance and emission characteristics of combustion systems. The asymmetric swirling flameless combustor offers potential advantages in terms of enhanced fuel flexibility, reduced pollutant emissions, and improved combustion stability. Through varying the recirculation ratio, the combustion performance and emission characteristics can be optimized to meet specific requirements. In this research, experimental investigations were conducted to analyse the effect of recirculation ratio on the combustion stability, temperature field and emission of the asymmetric swirling flameless combustion. From the results obtained, it was observed that recirculation ratio has significant effect on the performance of the combustor i.e., as the recirculation ratio increases due to decrease in the exhaust area, more uniform temperature and less emission was observed. At 30mm exhaust diameter and lean condition, average recirculation of 7.21 was obtained with 2ppm NOx emission and 118ppm CO emission along with uniform temperature in the combustion zone.
29
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.
30
Castro, Zamir Sánchez, Hugo Reinel García Bernal e Oscar Andrés Mendieta Menjura. "Efecto del precalentamiento del aire primario y la humedad del bagazo de caña de azúcar durante la combustión en lecho fijo". Corpoica Ciencia y Tecnología Agropecuaria 14, n. 1 (24 maggio 2013): 5. http://dx.doi.org/10.21930/rcta.vol14_num1_art:263.
Testo completoAbstract (sommario):
<p>Los hornos utilizados para la elaboración de panela presentan pérdidas energéticas debido a una combustión incompleta del bagazo de caña de azúcar y al calor sensible en los gases de chimenea. Durante el proceso de producción de panela, el bagazo de caña de azúcar se utiliza como combustible, con fracciones másicas de humedad entre 30% y 50%, las cuales afectan el rendimiento de la combustión de una biomasa en lecho fijo. Gracias a que el precalentamiento del aire disminuye el tiempo de secado, su implementación en muchos sistemas de combustión de biomasa ha incrementado la eficiencia del proceso. Por tanto, en la presente investigación se estudió la influencia del contenido de humedad y el precalentamiento del aire primario sobre la temperatura, la composición del gas y la tasa de combustión, mediante un diseño experimental factorial mixto 3x2. Los resultados demostraron que el aumento en la humedad del bagazo de caña reduce la tasa de combustión y la conversión de carbono a CO2, y por tanto, el rendimiento del proceso. Cuando se precalentó el aire primario hasta una temperatura de 120 ºC, la tasa de combustión aumentó, sin embargo sólo significó un incremento en el rendimiento de la combustión para una fracción másica de humedad de 30%.</p><p><strong>Effect of primary air preheating and moisture sugarcane bagasse during fixed bed combustion</strong></p><p>Furnaces used to making jaggery have energy losses due to incomplete combustion of sugarcane bagasse and sensible heat in the flue gases. During jaggery production process, sugarcane bagasse is used as fuel, with mass fractions of humidity between 30% and 50%, which affect the combustion efficiency of a biomass in a fixed bed. Because the air preheating decreases the drying time, its implementation in many biomass combustion systems increases process efficiency. Therefore, in this investigation we studied the influence of the moisture content and the preheating of the primary air on the combustion of bagasse in a fixed bed furnace, by analyzing the profiles of temperature and concentration of the combustion gas. Results showed that increasing in bagasse moisture reduces the rate of combustion and conversion of carbon to CO2, diminishing the yield of process. When the primary air is preheated to a temperature of 120 ºC, the combustion rate increased, however, only meant an increase in combustion efficiency to a mass fraction of 30% humidity.</p>
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Nair, Vineeth, e R. I. Sujith. "Multifractality in combustion noise: predicting an impending combustion instability". Journal of Fluid Mechanics 747 (23 aprile 2014): 635–55. http://dx.doi.org/10.1017/jfm.2014.171.
Testo completoAbstract (sommario):
AbstractThe transition in dynamics from low-amplitude, aperiodic, combustion noise to high-amplitude, periodic, combustion instability in confined, combustion environments was studied experimentally in a laboratory-scale combustor with two different flameholding devices in a turbulent flow field. We show that the low-amplitude, irregular pressure fluctuations acquired during stable regimes, termed ‘combustion noise’, display scale invariance and have a multifractal signature that disappears at the onset of combustion instability. Traditional analysis often treats combustion noise and combustion instability as acoustic problems wherein the irregular fluctuations observed in experiments are often considered as a stochastic background to the dynamics. We demonstrate that the irregular fluctuations contain useful information of prognostic value by defining representative measures such as Hurst exponents that can act as early warning signals to impending instability in fielded combustors.
32
Isvoranu, Dragos D., e Paul G. A. Cizmas. "Numerical Simulation of Combustion and Rotor-Stator Interaction in a Turbine Combustor". International Journal of Rotating Machinery 9, n. 5 (2003): 363–74. http://dx.doi.org/10.1155/s1023621x03000344.
Testo completoAbstract (sommario):
This article presents the development of a numerical algorithm for the computation of flow and combustion in a turbine combustor. The flow and combustion are modeled by the Reynolds-averaged Navier-Stokes equations coupled with the species-conservation equations. The chemistry model used herein is a two-step, global, finite-rate combustion model for methane and combustion gases. The governing equations are written in the strong conservation form and solved using a fully implicit, finite-difference approximation. The gas dynamics and chemistry equations are fully decoupled. A correction technique has been developed to enforce the conservation of mass fractions. The numerical algorithm developed herein has been used to investigate the flow and combustion in a one-stage turbine combustor.
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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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Serbin, Sergey. "THERMO ACOUSTIC PROCESSES IN LOW EMISSION COMBUSTION CHAMBER OF GAS TURBINE ENGINE CAPACITY 25 MW". Science Journal Innovation Technologies Transfer, n. 2019-2 (5 maggio 2019): 86–90. http://dx.doi.org/10.36381/iamsti.2.2019.86-90.
Testo completoAbstract (sommario):
The appliance of modern tools of the computational fluid dynamics for the investigation of the pulsation processes in the combustion chamber caused by the design features of flame tubes and aerodynamic interaction compressor, combustor and turbine is discussed. The aim of the research is to investigate and forecast the non-stationary processes in the gas turbine combustion chambers. The results of the numerical experiments which were carried out using three-dimensional mathematical models in gaseous fuels combustion chambers reflect sufficiently the physical and chemical processes of the unsteady combustion and can be recommended to optimize the geometrical and operational parameters of the low-emission combustion chamber. The appliance of such mathematical models are reasonable for the development of new samples of combustors which operate at the lean air-fuel mixture as well as for the modernization of the existing chambers with the aim to develop the constructive measures aimed at reducing the probability of the occurrence of the pulsation combustion modes. Keywords: gas turbine engine, combustor, turbulent combustion, pulsation combustion, numerical methods, mathematical simulation.
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Brookes, S. J., R. S. Cant, I. D. J. Dupere e A. P. Dowling. "Computational Modeling of Self-Excited Combustion Instabilities". Journal of Engineering for Gas Turbines and Power 123, n. 2 (1 gennaio 2001): 322–26. http://dx.doi.org/10.1115/1.1362662.
Testo completoAbstract (sommario):
It is well known that lean premixed combustion systems potentially offer better emissions performance than conventional non-premixed designs. However, premixed combustion systems are more susceptible to combustion instabilities than non-premixed systems. Combustion instabilities (large-scale oscillations in heat release and pressure) have a deleterious effect on equipment, and also tend to decrease combustion efficiency. Designing out combustion instabilities is a difficult process and, particularly if many large-scale experiments are required, also very costly. Computational fluid dynamics (CFD) is now an established design tool in many areas of gas turbine design. However, its accuracy in the prediction of combustion instabilities is not yet proven. Unsteady heat release will generally be coupled to unsteady flow conditions within the combustor. In principle, computational fluid dynamics should be capable of modeling this coupled process. The present work assesses the ability of CFD to model self-excited combustion instabilities occurring within a model combustor. The accuracy of CFD in predicting both the onset and the nature of the instability is reported.
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Sanata, Andi, Nasrul Ilminnafik, Muhammad Maulana Asyhar, Hendry Y. Nanlohy, Franciscus Xaverius Kristianta e Imam Sholahuddin. "Characterization of Combustion in Cylindrical Meso-Scale Combustor with Wire Mesh Flame Holder as Initiation of Energy Source for Future Vehicles". Automotive Experiences 7, n. 1 (27 aprile 2024): 97–110. http://dx.doi.org/10.31603/ae.10715.
Testo completoAbstract (sommario):
The research aims to analyze and reveal combustion characteristics in a Cylindrical Meso Scale (CMS) Combustor with a wire mesh flame holder as a reference for designing a compact, efficient, and high-density energy source for future vehicles. This experiment analyzes the combustion ’s of a butane gas (C4H10)-air mixture in a cylindrical meso-scale (CMS) combustor with the addition of wire mesh flame holder on the stability of the combustion flame, as initiation of future vehicle energy source. The diameter of the CMS combustor with wire mesh flame holder is varied to give an idea of the effect of heat loss on the combustion flame's characteristics. The results show that the wire mesh as a flame holder is essential in the combustion stabilization mechanism. A stable flame can be stabilized in a CMS combustor with wire mesh. Variations in the diameter of the CMS combustor will result in variations in the surface-to-volume ratio, heat loss, and contact area of the wire mesh flame holder. At a large diameter, it produces the characteristics of a combustion flame with a more stable flame stability limit than a smaller diameter, a dimmer flame visualization than a smaller diameter at the same air and fuel discharge, a more distributed flame mode map area than the smaller diameter, lower flame temperature and combustor wall temperature than the smaller diameter, and relatively higher energy output than the smaller diameter.
37
Colantonio, R. O. "The Applicability of Jet-Shear-Layer Mixing and Effervescent Atomization for Low-NOx Combustors". Journal of Engineering for Gas Turbines and Power 120, n. 1 (1 gennaio 1998): 17–23. http://dx.doi.org/10.1115/1.2818073.
Testo completoAbstract (sommario):
An investigation has been conducted to develop appropriate technologies for a low-NOx, liquid-fueled combustor. The combustor incorporates an effervescent atomizer used to inject fuel into a premixing duct. Only a fraction of the combustion air is used in the premixing process. This fuel-rich mixture is introduced into the remaining combustion air by a rapid jet-shear-layer mixing process involving radial fuel–air jets impinging on axial air jets in the primary combustion zone. Computational modeling was used as a tool to facilitate a parametric analysis appropriate to the design of an optimum low-NOx combustor. A number of combustor configurations were studied to assess the key combustor technologies and to validate the three-dimensional modeling code. The results from the experimental testing and computational analysis indicate a low-NOx potential for the jet-shear-layer combustor. Key features found to affect NOx emissions are the primary combustion zone fuel–air ratio, the number of axial and radial jets, the aspect ratio and radial location of the axial air jets, and the radial jet inlet hole diameter. Each of these key parameters exhibits a low-NOx point from which an optimized combustor was developed. Also demonstrated was the feasibility of utilizing an effervescent atomizer for combustor application. Further developments in the jet-shear-layer mixing scheme and effervescent atomizer design promise even lower NOx with high combustion efficiency.
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Hosseini, Seyed, Evan Owens, John Krohn e James Leylek. "Experimental Investigation into the Effects of Thermal Recuperation on the Combustion Characteristics of a Non-Premixed Meso-Scale Vortex Combustor". Energies 11, n. 12 (4 dicembre 2018): 3390. http://dx.doi.org/10.3390/en11123390.
Testo completoAbstract (sommario):
In small-scale combustors, the ratio of area to the combustor volume increases and hence heat loss from the combustor’s wall is significantly enhanced and flame quenching occurs. To solve this problem, non-premixed vortex flow is employed to stabilize flames in a meso-scale combustion chamber to generate small-scale power or thrust for propulsion systems. In this experimental investigation, the effects of thermal recuperation on the characteristics of asymmetric non-premixed vortex combustion are studied. The exhaust gases temperature, emissions and the combustor wall temperature are measured to evaluate thermal and emitter efficiencies. The results illustrate that in both combustors (with/without thermal recuperator), by increasing the combustion air mass flowrate, the wall temperature increases while the wall temperature of combustor with thermal recuperator is higher. The emitter efficiency calculated based on the combustor wall temperature is significantly increased by using thermal recuperator. Thermal efficiency of the combustion system increases up to 10% when thermal recuperator is employed especially in moderate Reynolds numbers (combustion air flow rate is 120 mg/s).
39
Som, S. K., S. S. Mondal e S. K. Dash. "Energy and Exergy Balance in the Process of Pulverized Coal Combustion in a Tubular Combustor". Journal of Heat Transfer 127, n. 12 (25 luglio 2005): 1322–33. http://dx.doi.org/10.1115/1.2101860.
Testo completoAbstract (sommario):
A theoretical model of exergy balance, based on availability transfer and flow availability, in the process of pulverized coal combustion in a tubular air-coal combustor has been developed to evaluate the total thermodynamic irreversibility and second law efficiency of the process at various operating conditions. The velocity, temperature, and concentration fields required for the evaluation of flow availability have been computed numerically from a two-phase separated flow model on a Eulerian-Lagrangian frame in the process of combustion of pulverized coal particles in air. The total thermodynamic irreversibility in the process has been determined from the difference in the flow availability at the inlet and outlet of the combustor. A comparative picture of the variations of combustion efficiency and second law efficiency at different operating conditions, such as inlet pressure and temperature of air, total air flow rate and inlet air swirl, initial mean particle diameter, and length of the combustor, has been provided to shed light on the trade-off between the effectiveness of combustion and the lost work in the process of pulverized coal combustion in a tubular combustor.
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Lefebvre, A. H. "Fuel Effects on Gas Turbine Combustion—Ignition, Stability, and Combustion Efficiency". Journal of Engineering for Gas Turbines and Power 107, n. 1 (1 gennaio 1985): 24–37. http://dx.doi.org/10.1115/1.3239693.
Testo completoAbstract (sommario):
An analytical study is made of the substantial body of experimental data acquired during recent Wright-Patterson Aero Propulsion Laboratory sponsored programs on the effects of fuel properties on the performance and reliability of several gas turbine combustors, including J79-17A, J79–17C (Smokeless), F101, TF41, TF39, J85, TF33, and F100. Quantitative relationships are derived between certain key aspects of combustion, notably combustion efficiency, lean blowout limits and lean light-off limits, and the relevant fuel properties, combustor design features, and combustor operating conditions. It is concluded that combustion efficiency, lean blowout limits, and lean lightoff limits are only slightly dependent on fuel chemistry, but are strongly influenced by the physical fuel properties that govern atomization quality and spray evaporation rates.
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Claeys, J. P., K. M. Elward, W. J. Mick e R. A. Symonds. "Combustion System Performance and Field Test Results of the MS7001F Gas Turbine". Journal of Engineering for Gas Turbines and Power 115, n. 3 (1 luglio 1993): 537–46. http://dx.doi.org/10.1115/1.2906741.
Testo completoAbstract (sommario):
This paper presents the results of the combustion system test of the MS7001F installed at the Virginia Power Chesterfield station. Tests of water and steam injection for NOx control were performed. Results of emissions, combustor dynamics, and combustor hardware performance are presented. Emissions test results include NOx, CO, unburned hydrocarbons, VOC, and formaldehyde levels. Combustor dynamic activity over a range of diluent injection ratios, and the performance of an actively cooled transition duct are also discussed. Combustion system mechanical performance is described following the first combustion system inspection.
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Chand, Dharmahinder Singh, Daamanjyot Barara, Gautam Ganesh e Suraj Anand. "Comparison of Efficiency of Conventional Shaped Circular and Elliptical Shaped Combustor". MATEC Web of Conferences 151 (2018): 02002. http://dx.doi.org/10.1051/matecconf/201815102002.
Testo completoAbstract (sommario):
There have been concerted efforts towards improving the fuel efficiency of the jet engines in the past, with an aim of reducing the incomplete combustion. The process of combustion in a jet engine takes place in the combustor. A study was conducted for enhancement of air-fuel mixing process by computational analysis of an elliptically shaped combustor for a gas turbine engine. The results of computational analysis of an elliptical shape combustor were compared with a circular shape combustor used in gas turbine engines with a identical cross sectional area. The comparison of the computationally derived parameters of the two combustors i.e. temperature, pressure, and velocity are studied and analyzed. The study intends towards the comparison of the combustion efficiencies of the circular and elliptically shaped combustors. The combustion efficency of elliptical chamber is found to be 98.72% at the same time it was observed 56.26% in case of circular type combustor.
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Cheng, Yuwei, Qian Chen, Xiaofei Niu e Shufeng Cai. "Large Eddy Simulation and Dynamic Mode Decomposition of Supersonic Combustion Instability in a Strut-Based Scramjet Combustor". Aerospace 10, n. 10 (29 settembre 2023): 857. http://dx.doi.org/10.3390/aerospace10100857.
Testo completoAbstract (sommario):
Supersonic combustion instability studies are crucial for the future maturation of scramjet engines. In the present paper, the supersonic combustion instability in a strut-based scramjet combustor is investigated through large eddy simulation and dynamic mode decomposition. The results show significant pressure oscillation in the strut-based scramjet combustor when the air parameters at the combustor inlet and the fuel parameters at the injector outlet are under certain conditions, and these pressure oscillation situations correspond to supersonic combustion instability. The oscillations have multiple dominant frequencies, including relatively low frequency of 2984 Hz, high frequency of 62,180 Hz, and very high frequency of 110,562 Hz. Large pressure oscillations in the strut-based scramjet combustor are closely related to wake instability, shear layer instability, shear layer and wave interactions, and combustion. Reducing the air total temperature at the combustor inlet can attenuate the pressure oscillations, and reducing the fuel flow rate at the injector outlet can also attenuate the pressure oscillations.
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Wakabayashi, T., S. Ito, S. Koga, M. Ippommatsu, K. Moriya, K. Shimodaira, Y. Kurosawa e K. Suzuki. "Performance of a Dry Low-NOx Gas Turbine Combustor Designed With a New Fuel Supply Concept". Journal of Engineering for Gas Turbines and Power 124, n. 4 (24 settembre 2002): 771–75. http://dx.doi.org/10.1115/1.1473154.
Testo completoAbstract (sommario):
This paper describes the performance of a dry low-NOx gas turbine combustor designed with a new fuel supply concept. This concept uses automatic fuel distribution achieved by an interaction between the fuel jet and the airflow. At high loads, most of the fuel is supplied to the lean premixed combustion region for low-NOx, while at low loads, it is supplied to the pilot combustion region for stable combustion. A numerical simulation was carried out to estimate the equivalence ratio in the fuel supply unit. Next, through the pressurized combustion experiments on the combustor with this fuel supply unit using natural gas as fuel, it was confirmed that NOx emissions were reduced and stable combustion was achieved over a wide equivalence ratio range.
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Yang, Pengnian, Zhixun Xia, Likun Ma, BinBin Chen, Yunchao Feng, Chaolong Li e Libei Zhao. "Influence of the Multicavity Shape on the Solid Scramjet". International Journal of Aerospace Engineering 2021 (26 ottobre 2021): 1–14. http://dx.doi.org/10.1155/2021/9718537.
Testo completoAbstract (sommario):
In this paper, a modular solid scramjet combustor with multicavity was proposed. The influence of multicavity shape on the performance of solid scramjet was investigated by the direct-connected tests. The experiments simulated a flight Mach 5.5 at 25 km. The boron-based fuel-rich propellant was used. The microstructure of combustion products was analyzed by SEM. The experimental results show that the fuel-rich mixture produced by the gas generator would ignite rapidly in the solid scramjet combustor. The combustion process showed a typical characteristic of establishment-development-maintenance-attenuation. Compared to the flame-holding cavity, the other shapes of cavities, e.g., narrow and lobe, can improve mixing and combustion. In our experiment, the combustion efficiency increased from 0.41 to 0.48, and the total pressure recovery was 0.36. In summary, the proposed solid scramjet combustor can effectively solve the ignition delay problem of the fuel-rich mixture, and the narrow/lobe cavity shows the ability to improve the mixing and combustion of the fuel-rich mixture.
46
Wang, Yue, Minqi Zhang, Shuhang Chang, Shengji Li e Xuefeng Huang. "Laser-Induced Ignition and Combustion Behavior of Individual Graphite Microparticles in a Micro-Combustor". Processes 8, n. 11 (19 novembre 2020): 1493. http://dx.doi.org/10.3390/pr8111493.
Testo completoAbstract (sommario):
Microscale combustion has potential application in a micro power generator. This paper studied the ignition and combustion behavior of individual graphite microparticles in a micro-combustor to explore the utilization of carbon-based fuels at the microscale system. The individual graphite microparticles inside the micro-combustor were ignited by a highly focused laser in an air flow with natural convection at atmospheric temperature and pressure. The results show that the ignition of graphite microparticles was heterogeneous. The particle diameter had a small weak effect on ignition delay time and threshold ignition energy. The micro-combustor wall heat losses had significant effects on the ignition and combustion. During combustion, flame instability, photophoresis, repetitive extinction and reignition were identified. The flame structure was asymmetric, and the fluctuation of flame front and radiation intensity showed combustion instability. Photophoretic force pushed the graphite away from the focal point and resulted in extinction. Owing to large wall heat loss, the flame quickly extinguished. However, the graphite was inductively reignited by laser.
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Chen, Yi, Li Fei, Liming He, Lei Zhang, Chunchang Zhu e Jun Deng. "The Influence of Dielectric Barrier Discharge Plasma on the Characteristics of Aero-Engine Combustion Chamber". Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, n. 2 (aprile 2019): 369–77. http://dx.doi.org/10.1051/jnwpu/20193720369.
Testo completoAbstract (sommario):
A test platform was developed to investigate the performance of aero-engine combustor by the dielectric barrier discharge (DBD) plasma assisted combustion (PAC) in the simulated maximum condition. Conventional combustion experiments and plasma-assisted combustion conditions were conducted to study the effect of PAC on the performances including average outlet temperature, combustion efficiency and pattern factor under four different excessive air coefficients five different voltages. The comparative experiment shows that the combustion efficiency is improved after PAC compared with the normal conditions, the combustion efficiency of PAC increases 2.31% in the fuel-rich condition when Up-p is 40 kV. The uniformity of the outlet temperature field is also improved after PAC, the decrease of the pattern factor is more than 5% in the fuel-rich condition. These results offer certain reference value for the future application of PAC in aero-engine combustor and improving its performance.
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Mat Zian, Norhaslina, Hasril Hasini e Nur Irmawati Om. "Preliminary CFD Investigation of Syngas Combustion at Different Operating Pressures". Applied Mechanics and Materials 786 (agosto 2015): 215–19. http://dx.doi.org/10.4028/www.scientific.net/amm.786.215.
Testo completoAbstract (sommario):
Study on the flow and combustion behavior inside gas turbine combustor used in thermal power plant is described in this paper. The combustion process takes place using synthetic gas and emphasis is given to the effect of pressure variation on flame profile, temperature distribution and emissions as compared to the conventional combustion using methane. The operating pressure of the can-type combustor varies in the range of 1-10 atm. while the syngas composition is assumed to have fixed values of 10% CH4, 55% CO, 30% H2 and 5% N2. Preliminary result shows that the flow inside the can-combustor is highly swirling which indicates good mixing of fuel and air prior to the entrance of the mixture to the main combustion zone. The temperature distribution at combustor mid plane show identical pattern for pressure range between 1-10 atm for both maximum and average temperature magnitude.
49
Mat Zian, Norhaslina, Hasril Hasini e Nur Irmawati Om. "Preliminary CFD Investigation of Syngas Combustion at Different Operating Pressure". Applied Mechanics and Materials 819 (gennaio 2016): 277–81. http://dx.doi.org/10.4028/www.scientific.net/amm.819.277.
Testo completoAbstract (sommario):
Study on the flow and combustion behavior inside gas turbine combustor used in thermal power plant is described in this paper. The combustion process takes place using synthetic gas and emphasis is given to the effect of pressure variation on flame profile, temperature distribution and emissions as compared to the conventional combustion using methane. The operating pressure of the can-type combustor varies in the range of 1-10 atm. while the syngas composition is assumed to have fixed values of 10% CH4, 55% CO, 30% H2 and 5% N2. Preliminary result shows that the flow inside the can-combustor is highly swirling which indicates good mixing of fuel and air prior to the entrance of the mixture to the main combustion zone. The temperature distribution at combustor mid plane show identical pattern for pressure range between 1-10 atm for both maximum and average temperature magnitude.
50
Pan, J. F., Z. Y. Hou, Y. X. Liu, A. K. Tang, J. Zhou, X. Shao, Z. H. Pan e Q. Wang. "Design and working performance study of a novel micro parallel plate combustor with two nozzles for micro thermophotovotaic system". Thermal Science 19, n. 6 (2015): 2185–94. http://dx.doi.org/10.2298/tsci141109069p.
Testo completoAbstract (sommario):
Micro-combustors are a key component in combustion-driven micro power generators, and their performance is significantly affected by their structure. For the application of micro-thermophotovoltaic (MTPV) system, a high and uniform temperature distribution along the walls of the micro combustor is desired. In this paper, a three-dimensional numerical simulation has been conducted on a new-designed parallel plate micro combustor with two nozzles. The flow field and the combustion process in the micro combustor, and the temperature distribution on the wall as well as the combustion efficiency were obtained. The effects of various parameters such as the inlet angle and the fuel volumetric flow rate on the performance of the micro combustor were studied. It was observed that a swirl formed in the center of the combustor and the radius of the swirl increased with the increase of the inlet rate, and the best working condition was achieved at the inlet angle ?=20?. The results indicated that the two-nozzle combustion chamber had a higher and more uniform mean temperature than the conventional combustor under the same condition.