Статті в журналах: "Fuel-air mixture"

1

Shayler, P. J., R. M. Isaacs, and T. H. Ma. "The variation of in-Cylinder Mixture Ratios during Engine Cranking at Low Ambient Temperatures." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 206, no. 1 (January 1992): 55–62. http://dx.doi.org/10.1243/pime_proc_1992_206_160_02.

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The development of mixture conditions in the cylinder of a fuel-injected spark ignition engine during engine cranking has been investigated at ambient temperatures down to —20°C. Mixtures near to the spark plug location were sampled and analysed to determine the air-fuel ratio and the relative proportions of light, medium and heavy components in the fuel. At low temperatures, the local air-fuel ratio varies substantially during the compression stroke, as does mixture composition. The change in mixture ratio over successive cycles of cranking depends on the fuel injected per cycle and the fuel-transfer characteristics of the intake port. The success or failure of combustion initiation is observed to depend only on the mixture air-fuel ratio at the spark plug. The upper limit on this mixture ratio for successful first-fire appears to be near to 35 : 1 by mass. Air-borne fuel in the cylinder accounts for only a small percentage of that supplied by the injector.

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2

Raide, Veljo, Risto Ilves, and Jüri Olt. "Air-Fuel Mixture Temperatures with Light and Heavy Fuels for Effective Spark Ignition Engine Work." Advances in Military Technology 16, no. 2 (December 15, 2021): 289–307. http://dx.doi.org/10.3849/aimt.01501.

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This research resulted from military interest in finding methods to provide distributed electricity generation in order to support comprehensive state defence measures. The aim of the study was to investigate the effect of a heated air-fuel mixture on the combustion process of a spark ignition (SI) engine, and to highlight the maximum temperatures to be applied to air-fuel mixtures with different fuel fractions in order to avoid any detonation of the fuel mixture in the engine. Tests were carried out with a petrol engine generator (GENSET) so that an investigation could be conducted into the effect of the air-fuel mixture on the engine’s combustion. It turned out that heating the air-fuel mixture permits the use of heavier fraction fuels than engine petrol in SI engines does, including diesel fuel and biodiesel fuel, and also that the use of heavy fraction fuels in SI engines is effective mainly under low and middle loads.

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3

Булат, П. В., К. Н. Волков, Л. П. Грачев, И. И. Есаков та П. Б. Лавров. "Воспламенение топливной смеси с помощью многоточечного импульсного искрового разряда при различных начальных условиях". Журнал технической физики 91, № 9 (2021): 1339. http://dx.doi.org/10.21883/jtf.2021.09.51212.92-21.

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The development of efficient and reliable systems for the ignition of air/fuel mixtures is of interest for many practical applications associated with the use of combustion devices. To increase the total surface of the flame, ensure the reliability of ignition, increase the rate of combustion in the volume of the chamber and the completeness of combustion of the combustible mixture, multi-point ignition of the air/fuel mixture using several pulsed spark discharges is used. A comparison of the characteristics of combustion products in the working chamber when using different numbers of igniting spark discharges is made based on the data of a physical experiment. Measurements are carried out at various ignition points of the mixture, initial mixture pressures, and air/fuel ratios. The values of the air/fuel ratio used in the experiment are in the range, the boundaries of which are the lower and upper concentration limits of the ignition of the propane-air mixture.

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4

Hamidi, Nurkholis. "Carbon Dioxide Effects on the Flammability Characteristics of Biogas." Applied Mechanics and Materials 493 (January 2014): 129–33. http://dx.doi.org/10.4028/www.scientific.net/amm.493.129.

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Flammability limits and flame speed of methane-carbon dioxide-air mixtures have been studied to understand the effect of carbondioxide on the flammability characteristic of biogas. The fuel of biogas discussed in this study was made by mixing gases of methane and carbon dioxide. The carbon dioxide was varied from 0% (by volume) untill reach the flammability limit of the stoikhiometri biogas-air mixtures. The observation was done using a cubic combustion bomb with the dimension of 500 mm x 200 mm x 10 mm with the initial condition being at room temperature and atmospheric pressure. The ignitor was set at the top of combustion bomb, so the flame propagated downward. Base on the observation results, the presence of carbon dioxide in the fuel ofbiogas caused the flammability limits of biogasair mixture narrower. The biogas-air mixture was still flammable with the highest content of carbon dioxide of 62.5 %vol when the mixture was sthoichiometri. Compared to methane-air mixture, the presence of carbon dioxide in biogas caused a reduction in the flame speed. The stoichiometri mixture has the highest flame speed when the carbon dioxide was not present in the fuel. However, when the carbon dioxide was added in the fuel, the rich mixture has the highest flame speed. This is a consequence of the rich biogas-air mixture having a higher fraction of the carbon dioxide components from the fuel compared to the stoichiometri and lean biogas-air mixture. The result also indicated that at the upper limit the flame still propagated downward to closed to the endwall. However, at the lower limit (lean mixtures), the flame did not intend to propagate downward, it was just at the top and propagate sideward.

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5

Asoyan, Arthur R., Igor K. Danilov, Igor A. Asoyan, and Georgy M. Polishchuk. "Hydrogen application in internal combustion engines." RUDN Journal of Engineering Researches 21, no. 1 (December 15, 2020): 14–19. http://dx.doi.org/10.22363/2312-8143-2020-21-1-14-19.

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A technical solution has been proposed to reduce the consumption of basic hydrocarbon fuel, to improve the technical, economic and environmental performance of internal combustion engines by affecting the combustion process of the fuel-air mixture with a minimum effective mass fraction of hydrogen additive in the fuel-air mixture. The burning rate of hydrogen-air mixtures is an order of magnitude greater than the burning rate of similar mixtures based on gasoline or diesel fuel, compared with the former, they are favorably distinguished by their greater detonation stability. With minimal additions of hydrogen to the fuel-air charge, its combustion time is significantly reduced, since hydrogen, having previously mixed with a portion of the air entering the cylinder and burning itself, effectively ignites the mixture in its entirety. Issues related to the accumulation of hydrogen on board the car, its storage, explosion safety, etc., significantly inhibit the development of mass production of cars using hydrogen fuel. The described technical solution allows the generation of hydrogen on board the car and without accumulation to use it as an additive to the main fuel in internal combustion engines. The technical result is to reduce the consumption of hydrocarbon fuels (of petroleum origin) and increase the environmental friendliness of the car due to the reduction of the emission of harmful substances in exhaust gases.

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6

Cernat, Alexandru, Constantin Pana, and Niculae Negurescu. "Aspects of in-Cylinder Mixture Formation Study for a Diesel Engine Fuelled with LPG by Diesel-Gas Method." Applied Mechanics and Materials 809-810 (November 2015): 1043–48. http://dx.doi.org/10.4028/www.scientific.net/amm.809-810.1043.

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The Liquid Petroleum Gas can be use for diesel engine fuelling with significant result in term of pollutant emissions improvement, with important reduction of nitrous oxides and smoke for a LPG dual fuelled diesel engine. Beside this the LPG fuelling affects the combustion process inside the cylinder and also the mixture forming. High degree of homogeneity of the air-LPG mixtures will accelerate the in-cylinder mixture forming between air-LPG and diesel fuel jets, since the LPG-air mixture combustion starts. The paper presents the results of a zero-dimensional, one-zone thermodynamic model developed by authors for diesel fuel jets vaporization and combustion at dual fuelling. The model shows the diesel fuel jet characteristic, the break-up period, the mass flow of vaporized substance on the particle surface, drops vaporization time, air-fuel mixture forming speed, drops combustion time and flame position, showing a significant influence of LPG cycle dose on their characteristic parameters. The drops vaporization and combustion duration decrease for dual fuelling and the flame radius increases. Thus, based on the experimental data, an evaluation model for mixture forming was developed for an automotive diesel engine fuelled with LPG and diesel fuel by diesel-gas method.

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7

Kessler, D. A., V. N. Gamezo, and E. S. Oran. "Gas-phase detonation propagation in mixture composition gradients." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, no. 1960 (February 13, 2012): 567–96. http://dx.doi.org/10.1098/rsta.2011.0342.

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The propagation of detonations through several fuel–air mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, inside of which the gradient of mixture composition is oriented normal to the direction of propagation. The simulations are performed using a two-component, single-step reaction model calibrated so that one-dimensional detonation properties of model low- and high-activation-energy mixtures are similar to those observed in a typical hydrocarbon–air mixture. In the low-activation-energy mixture, the reaction zone structure is complex, consisting of curved fuel-lean and fuel-rich detonations near the line of stoichiometry that transition to decoupled shocks and turbulent deflagrations near the channel walls where the mixture is extremely fuel-lean or fuel-rich. Reactants that are not consumed by the leading detonation combine downstream and burn in a diffusion flame. Detonation cells produced by the unstable reaction front vary in size across the channel, growing larger away from the line of stoichiometry. As the size of the channel decreases relative to the size of a detonation cell, the effect of the mixture composition gradient is lessened and cells of similar sizes form. In the high-activation-energy mixture, detonations propagate more slowly as the magnitude of the mixture composition gradient is increased and can be quenched in a large enough gradient.

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8

Korohodskyi, Volodymyr, Andrii Rogovyi, Oleksandr Voronkov, Andrii Polivyanchuk, Pavlo Gakal, Oleksii Lysytsia, Igor Khudiakov, Tamara Makarova, Mariіa Hnyp, and Yevhen Haiek. "Development of a three-zone combustion model for stratified-charge spark-ignition engine." Eastern-European Journal of Enterprise Technologies 2, no. 5 (110) (April 30, 2021): 46–57. http://dx.doi.org/10.15587/1729-4061.2021.228812.

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A thermodynamic model for calculating the operating process in the cylinder of a spark-ignition engine with internal mixture formation and stratified air-fuel charge based on the volume balance method was developed. The model takes into account the change in the working fluid volume during the piston movement in the cylinder. The equation of volume balance of internal mixture formation processes during direct fuel injection into the engine cylinder was compiled. The equation takes into account the adiabatic change in the volume of the stratified air-fuel charge, consisting of fuel-air mixture volume and air volume. From the heat balance equation, the change in the fuel-air mixture volume during gasoline evaporation in the fuel stream and from the surface of the fuel film due to external heat transfer was determined. Basic equations of combustion-expansion processes of the stratified air-fuel charge were derived, taking into account three zones corresponding to combustion products, fuel-air mixture and air volumes. The equation takes into account the change in the working fluid volume due to heat transfer and heat exchange between the zones and the walls of the above-piston volume. Dependences for determining the temperature in the three considered zones and pressure in the cylinder were obtained. Graphs of changes in the volumes of the combustion products, fuel-air mixture and air zones with the change of the above-piston volume in partial load modes (n=3,000 rpm) were plotted. With increasing load from bmep=0.144 MPa to bmep=0.322 MPa, at the moment of fuel ignition, the volume of the fuel-air mixture increases from 70 % to 92 % of the above-piston volume. At the same time, the air volume decreases from 30 % to 8 %. Analysis of theoretical and experimental indicator diagrams showed that discrepancies in the maximum combustion pressure do not exceed 5 %

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9

Green, H. G., J. H. Whitelaw, and K. Y. Wong. "Air-Fuel Mixture Characteristics of Reciprocating Engines." Combustion Science and Technology 59, no. 4-6 (June 1988): 225–46. http://dx.doi.org/10.1080/00102208808947098.

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10

OKAJIMA, Satoshi. "Measurement of burning velocity on DME fuel-air mixtures using microgravity technique." Combustion Engines 122, no. 3 (July 1, 2005): 56–60. http://dx.doi.org/10.19206/ce-117400.

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Experiment has been carried out to examine the fundamental combustion characteristics of DME fuel-air mixtures using micro-gravity technique, which is achieved in freely falling chamber. The initial conditions of temperature and pressure are 293 K and 0.10 MPa, respectively and the equivalence ratio is the range from stoichiometoric proportion to near the lower flammability limit. The results obtained in the study are as follows:(1) micro-gravity technique is very useful to analyze the flame behavior even at very lean mixtures, and (2) the burning velocity of DME fuel- air mixture is nearly the same with that of methane-air mixture at the range of all the equivalence ratios investigated and those values of DME fuel are 10.0 cm/s and 32.0 cm/s at 0.62 and 0.90 of equivalence ratio, respectively, and (3) from these experimental data it is suggested that the application to the engine combustion of DME fuel is not so impossible.

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11

Dodds, W. J., and E. E. Ekstedt. "Evaluation of Fuel Preparation Systems for Lean Premixing-Prevaporizing Combustors." Journal of Engineering for Gas Turbines and Power 108, no. 2 (April 1, 1986): 391–95. http://dx.doi.org/10.1115/1.3239917.

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A series of tests was conducted to provide data for the design of premixing-prevaporizing fuel-air mixture preparation systems for aircraft gas turbine engine combustors. Fifteen configurations of four different fuel-air mixture preparation system design concepts were evaluated to determine fuel-air mixture uniformity at the system exit over a range of conditions representative of cruise operation for a modern commercial turbofan engine. Operating conditions, including pressure, temperature, fuel-air ratio, and velocity had no clear effect on mixture uniformity in systems which used low-pressure fuel injectors. However, performance of systems using pressure atomizing fuel nozzles and large-scale mixing devices was shown to be sensitive to operating conditions. Variations in system design variables were also evaluated and correlated. Mixture uniformity improved with increased system length, pressure drop, and number of fuel injection points per unit area. A premixing system compatible with the combustor envelope of a typical combustion system and capable of providing mixture nonuniformity (standard deviation/mean) below 15% over a typical range of cruise operating conditions was demonstrated.

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12

Торба, Юрій Іванович, Дмитро Вікторович Павленко та Віталій Вікторович Манжос. "Моделювання якісного складу паливно-повітряної суміші у факельному запальнику камер згоряння ГТД". Aerospace technic and technology, № 5 (6 жовтня 2021): 39–47. http://dx.doi.org/10.32620/aktt.2021.5.05.

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The qualitative composition of the fuel-air mixture, which is formed in the torch igniter of the combustion chamber of the gas turbine engine (GTE), determines the efficiency and reliability of their work. The main task of the study is to determine the qualitative composition of the fuel-air mixture near the electric spark plug of the GTE torch igniter depending on its geometric features and engine operation condition. The composition of the mixture was evaluated using analytical, experimental, and numerical methods. According to the analytical model, a significant over-enrichment of the fuel-air mixture in the igniter housing was established and confirmed experimentally. A numerical model was used to determine the fields of mass concentration of fuel particles in the fuel-air mixture in the torch igniter housing, considering the peculiarities of airflow and fuel supply for different combinations of GTE design features and operating conditions. The influence of geometric parameters of the housing and external factors was investigated using the numerical model of stationary combustion of fuel-air mixture, which was prepared in the torch igniter housing of GTE combustion chamber by evaporation and spraying of aviation kerosene particles in the air stream. The implementation of a small-factor experiment allowed to establish the degree of influence of each factor under study and their interaction on the excess air coefficient. The correlation coefficient between the coefficient of excess air near the spark plug and the average flame temperature is set. Given the absence of serial designs of controller torch ignites, it is proposed to use a pulsed fuel supply to control the quality of the fuel-air mixture. Further ways of research to increase the reliability of ignition of both the torch igniter from the electric spark plug and the combustion chamber of GTE from the flame is outlined.

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13

Wierzba, I., and K. Kar. "Flame Flashback Within Turbulent Streams of Lean Homogeneous Fuel Mixtures and Air." Journal of Energy Resources Technology 114, no. 2 (June 1, 1992): 142–45. http://dx.doi.org/10.1115/1.2905933.

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The flame flashback limit represents the minimum concentration of the fuel in the stream of homogeneous mixtures of fuel and air at which a flame can propagate upstream against the direction of the flow. Information about these limits is important in the assessment of the safety of operation in situations where a flowing homogeneous fuel-air mixture is present. The present work examines the flame flashback in turbulent homogeneous fuel-air streams with Reynolds number up to 16,000. The flashback limits were established for a number of common gaseous fuels, such as methane, propane, hydrogen, ethylene, and their binary mixtures. Taking into consideration the wide use of low heating value fuels, the effect of the presence of diluents (nitrogen and carbon dioxide) in the fuel on the flashback limit was also investigated. Correlations were proposed to calculate the flashback limits of fuel mixtures and their accuracy is discussed.

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14

Wang, Dong, Yang Du, Xin Sheng Jiang, Jian Jun Liang, and Jian Zhong Zhou. "Experimental Study on Dispersion and Explosion Process of Fuel-Air Mixture in Underground Fuel Depot." Applied Mechanics and Materials 590 (June 2014): 261–65. http://dx.doi.org/10.4028/www.scientific.net/amm.590.261.

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In this paper, the fuel-air dispersion and explosion experimental system was designed and experimental simulation on fuel-air mixture spreading and exploding in long-narrow underground fuel depot was carried out. The special phenomena of fuel-air mixture dispersion and explosion process, the characteristic feature of the pressure curve and mechanism were analyzed. The explosion process can be divided into three stages: flame accelerating section, oscillating reaction section and wave dissipating section. And under the same initial conditions, if the ignition time advanced, there is a significant intermittent and large fluctuations phenomenon.

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15

Kislov, Oleh, Maya Ambrozhevich, and Mykhailo Shevchenko. "Development of a method to improve the calculation accuracy of specific fuel consumption for performance modeling of air-breathing engines." Eastern-European Journal of Enterprise Technologies 2, no. 8 (110) (April 30, 2021): 23–30. http://dx.doi.org/10.15587/1729-4061.2021.229515.

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Determination of specific fuel consumption of air-breathing engines is one of the problems of modeling their performance. As a rule, the estimation error of the specific fuel consumption while calculating air-breathing engine performance is greater than that of thrust. In this work, this is substantiated by the estimation error of the fuel-air ratio, which weakly affects thrust but significantly affects the specific fuel consumption. The presence of a significant error in the fuel-air ratio is explained by the use of simplified methods, which use the dependence of enthalpy as a function of mixture temperature and composition without taking into account the effect of pressure. The developed method to improve the calculation accuracy of specific fuel consumption of air-breathing engines is based on the correction of the fuel-air ratio in the combustor, determined by the existing mathematical models. The correction of the fuel-air ratio is made using the dependences of enthalpy on mixture temperature, pressure and composition. The enthalpy of the mixture is calculated through the average isobaric heat capacity obtained by integrating the isobaric heat capacity, depending on mixture temperature, pressure and composition. The calculation accuracy of the fuel-air ratio was verified by comparing it with the known experimental data on the combustion chamber of the General Electric CF6-80A engine (USA). The average calculation error of the fuel-air ratio does not exceed 3 %. The developed method was applied for correcting the specific fuel consumption for calculating the altitude-airspeed performance of the D436-148B turbofan engine (Ukraine), which made it possible to reduce the estimation error of the fuel-air ratio and specific fuel consumption to an average of 3 %

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16

Klimov, V. N., D. Ya Dud’ev, V. Ya Sigaylo, N. I. Klimov, and Yu K. Mashkov. "Research of the operability of an air-fuel lubrication and cooling system of gas turbine engine rotor bearings." VESTNIK of Samara University. Aerospace and Mechanical Engineering 18, no. 1 (April 16, 2019): 55–66. http://dx.doi.org/10.18287/2541-7533-2019-18-1-55-66.

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The article is devoted to the problem of ensuring the operability of air-fuel lubrication and cooling systems for gas turbine engine (GTE) rotor bearings. The paper considers one of the advanced designs of a GTE in which an air-fuel mixture obtained in a special mixer is fed to a bearing installed in the turbine support and then through a hollow shaft to the bearing of the compressor support and then directed to the engine input. It is difficult to implement such a GTE scheme because of the necessity to ensure the operability of bearings lubricated with an air-fuel mixture for a predetermined period of time. It is impossible to determine the thermal state of the bearings and the friction regime in them with sufficient accuracy. The solution of the problems requires carrying out experimental work to determine the coefficients of friction and convective heat transfer in the bearings, as well as their full service life under various operating conditions and parameters of the air-fuel mixture blown through the bearings. The paper presents the results of testing a 45-126205РЯ radial thrust bearing lubricated with an air-fuel mixture, МС-8П oil and a non-lubricated bearing of the same kind. The operability of the GTE rotor bearings lubricated with the air-fuel mixture is analyzed, the area of efficient application of the gas turbine engine with an air-fuel lubrication system is determined.

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17

Du, Yang, Jian Feng Gao, and Xin Sheng Jiang. "Studies of Fuel-Air Mixture Explosion Characteristics and Structure Fracture and Damage in Large-Scale Metal Oil Storage Tank." Key Engineering Materials 324-325 (November 2006): 1031–34. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.1031.

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The fuel-air mixture explosion incidents in the large-scale metal oil storage tank are frequent occurrence and rapidly extend because of the tank structure being fractured and damaged by the fuel-air mixture explosion. In this paper, the simulation experiment and numerical simulation has been carried out for the fuel-air mixture explosion in the large-scale metal storage tank. The shock waves characteristic of the explosive pressure has been studied and discussed. The fracture and damage effects caused by the shock waves characteristic to the tank structure has been analyzed and discussed too.

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18

Feng, Li Yan, Chun Hua Zhang, Jiang Ping Tian, Wu Qiang Long, Jun Li, Jin Cheng Li, and Yan Feng Gong. "Combustion System Optimization of a Gasoline Direct Injection Engine." Advanced Materials Research 354-355 (October 2011): 419–28. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.419.

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With the purpose of optimizing the combustion system of a homogeneous charged gasoline direct injection engine, its working process was simulated with a 3-D CFD software package. The authors investigated the influence of injection timings and combustion chamber shapes on the charge motion, fuel injection and their influence on fuel-air mixture formation. With the comparisons of fuel-air mixture quality and combustion processes between two typical injection timings, the optimal injection strategy was chosen. To further improve the mixture quality, configuration on piston crown was optimized and analysis on mixture formation processes of the new configurations was made. Simulation results indicate that the new configurations have faster fuel evaporation rate and better mixture homogeneity.

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19

Ikpe, A. E., and I. B. Owunna. "A 3D modelling of the in-cylinder combustion dynamics of two stroke internal combustion engine in its service condition." Nigerian Journal of Technology 39, no. 1 (April 3, 2020): 161–72. http://dx.doi.org/10.4314/njt.v39i1.18.

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In this study, a two stroke internal combustion engine was successfully modeled as a closed cycle with the intake, compression, expansion and exhaust processes considered in two strokes of the reciprocating piston. The in-cylinder combusted gases with respect to air-fuel mixture of 14.4:1 in the two stroke engine model were analyzed, showing the dynamics of the combusted gases, the flame pressure and temperature trajectories. It was observed that provided compression and expansion takes place at air-fuel mixture near ideal condition (14.7:1), the combusted gas temperature which occurred in the range of 293.92-3000.60 K is directly proportional to the cylinder gas pressure which occurred in the range of 60.76-80.20 bar. With a heat transfer coefficient of 581.236 W/m2K, the maximum temperature of the IC engine material was found to be 2367.56K at equilibrium and the maximum shear stress was found to be 176 x 102 MPa (1.76 x 105 bar). The 14.4:1 air-fuel mixture implies that 26% O2, 73% N2 and 1% trace gases are the in-cylinder air constituent that will react with 1 mole of hydrocarbon to form the combusted products of 96.2% CO2, 3.2% H2O and 0.6% N2. This will vary in conditions where the air-fuel mixture changes. Keywords: Modelling, Gas dynamics, Two stroke, IC engine, Air-fuel mixture.

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20

Wierzba, I., and G. A. Karim. "The Flammability of Fuel Mixtures in Air Containing Propane and Butane." Journal of Energy Resources Technology 111, no. 2 (June 1, 1989): 100–103. http://dx.doi.org/10.1115/1.3231403.

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The behavior of the lean and rich flammability limits of various fuel mixture combinations involving propane, n-butane, propylene and ethylene, which feature prominently in a variety of industrial and natural fuel gases such as liquefied petroleum gases (LPGs), was examined. It was found that the lean limits of such mixtures can be predicted well by using Le Chatelier’s Rule. This rule can also predict the rich flammability limits of propane-n-butane mixtures. However, its application to calculate the rich limits of mixtures such as propane-propylene, propane-ethylene, butane-ethylene, propylene-ethylene mixtures carries a significant error with certain mixtures composition. The effect of the dilution of such fuel mixtures with nitrogen or carbon dioxide was also investigated and a predictive procedure is described.

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21

Khalid, Amir, Christian Yohan M. Jaat, Izzuddin Zaman, B. Manshoor, and M. F. M. Ali. "Effect of Preheated Fuel on Mixture Formation of Biodiesel Spray." Applied Mechanics and Materials 393 (September 2013): 493–98. http://dx.doi.org/10.4028/www.scientific.net/amm.393.493.

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The key issue in using vegetable oil-based fuels is oxidation stability, stoichiometric point, bio-fuel composition, antioxidants on the degradation and viscosity thus influences to the different spray atomization and fuel air mixing characteristics. Purpose of this study is to investigate the effect of preheated biodiesel on fuel properties, spray characteristics and mixture formation. The detail behavior of mixture formation was investigated using the direct photography system with a digital color camera. This method can capture spray evaporation, spray length and mixture formation clearly with real images. Increased preheated fuel is found to enhance the spray penetration, resulting in increased the spray area and enhanced fuel-air premixing.

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22

Kakuho, A., Y. Hashizume, T. Urushihara, T. Itoh, and T. Mansion. "Infrared absorption technique for measuring local fuel concentration near the spark plug of a port injection gasoline engine." International Journal of Engine Research 10, no. 4 (June 17, 2009): 265–74. http://dx.doi.org/10.1243/14680874jer03609.

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The mixture concentration in the vicinity of the spark plug at the time of spark ignition is a critical parameter for the performance of SI engines. Infrared absorption is often used to measure this parameter in firing cycles. Although it is well known that the mixture concentration near the spark plug is a primary factor explaining combustion stability in direct injection engines, the effect of the local mixture concentration has not been confirmed for nearly homogeneous mixtures. In this research, the mixture concentration in the vicinity of the spark plug was measured quantitatively using infrared absorption with an optical fibre sensor built into the spark plug of a port injection engine. Measurements were made across a range of air—fuel ratios for both steady state conditions at three different overall air—fuel ratios and for a rich-to-lean transient condition. It was experimentally confirmed that the mixture concentration near the spark plug has little impact on combustion stability for steady state operation with a homogeneous mixture distribution. It has also been confirmed that fibre-sensor-based infrared absorption can be used for cycle-by-cycle analysis of the local mixture concentration even for a homogeneous mixture distribution.

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23

Popa, Cătălin Mihai, Silviu Marin Nan, Mihaela Părăian, Adrian Jurca, and Florin Păun. "Aspects of laboratory tests for the determination of the minimum ignition energy of the fuel / dust mixture." MATEC Web of Conferences 342 (2021): 04004. http://dx.doi.org/10.1051/matecconf/202134204004.

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During the technological processes of processing, production, handling and storage of combustible dusts, complex explosive mixtures may occur, the characteristics of which, in most cases, cannot be assimilated with the existing data in the specialized literature. If these combustible dusts are mixed with air in appropriate proportions and are initiated by an efficient source of ignition, they can burn rapidly and with considerable explosive force. One of the most common sources of ignition of potentially explosive atmospheres generated by the dust / air mixture is static electricity, materialized by electrostatic discharges. In order to assess the risk of ignition of an explosive mixture of air / dust, it is necessary to know the sensitivity of the explosive atmosphere to ignition, ie the value of the minimum ignition energy of the explosive mixture, which is then compared with the energy resulting from an electrostatic discharge. The paper presents a comparative analysis regarding the methods of determining the minimum ignition energy for air / fuel dust mixtures, using different devices, on the same type of dust.

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24

MORITA, Shigeyuki, and Takeshi TAKIYAIMA. "Air fuel ratio control for a lean mixture combustion." Transactions of the Japan Society of Mechanical Engineers Series B 52, no. 484 (1986): 4075–78. http://dx.doi.org/10.1299/kikaib.52.4075.

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25

OHTOMO, Mitsuaki, Seiji YAMAMOTO, and Hiroshi MIYAGAWA. "Effect of fuel-air mixture dilution on knock intensity." Transactions of the JSME (in Japanese) 82, no. 844 (2016): 16–00185. http://dx.doi.org/10.1299/transjsme.16-00185.

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26

TATEMICHI, Satoru, Atsuyoshi TAKAYAMA, Ikumi SHIGEMATSU, and Yuta KAMIRYO. "Combustion Characteristics of Air Mixture Fuel Using Distilled BDF." Proceedings of the National Symposium on Power and Energy Systems 2019.24 (2019): E213. http://dx.doi.org/10.1299/jsmepes.2019.24.e213.

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27

Yoon, Sung Pil, Hyun Jae Kim, Byung-Tak Park, Suk Woo Nam, Jonghee Han, Tae-Hoon Lim, and Seong-Ahn Hong. "Mixed-Fuels Fuel Cell Running on Methane-Air Mixture." Journal of Fuel Cell Science and Technology 3, no. 1 (August 23, 2005): 83–86. http://dx.doi.org/10.1115/1.2134741.

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In order to develop solid oxide fuel cells (SOFCs) running on hydrocarbon fuels, we have focused on a new method of improving electrode performance and reducing carbon deposition by coating thin films of samaria-doped ceria (SDC) within the pores of electrode by a sol-gel coating technique. The SDC coating on the pores of anode made it possible to have a good stability for long-term operation due to low carbon deposition and nickel sintering. In this study, we demonstrated a new method of improving electrode performance and reducing carbon deposition by coating thin films of samaria-doped ceria and applied the modification technique to two different types of fuel cell structures, anode-supported SOFC and comb-shaped SOFC. From our results, the maximum power density of an anode-supported cell (electrolyte; 8 mol% YSZ and thickness of 30μm, and cathode; La0.85Sr0.15MnO3) with the modified anode was ∼300mW∕cm2 at 700°C in the mixture of methane (25%) and air (75%) as the fuel, and air as the oxidant. The cell was operated for 500hr without significant degradation of cell performance. For the comb-shaped SOFCs operated in the mixed-fuels fuel cell conditions, the cell performance was 40mW∕cm2 at 700°C in the CH4∕O2 ratio of 1.

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28

Tamanini, Francesco, and Jeffrey L. Chaffee. "Mixture reactivity in explosions of stratified fuel/air layers." Process Safety Progress 19, no. 4 (2000): 219–27. http://dx.doi.org/10.1002/prs.680190407.

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29

Wang, T., Z. Peng, S.-L. Liu, H.-D. Xiao, and H. Zhao. "Optimization of stratification combustion in a spark ignition engine by double-pulse port fuel injection." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 221, no. 7 (July 1, 2007): 845–57. http://dx.doi.org/10.1243/09544070jauto376.

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The potential of lean burn in a spark-ignition (SI) engine with optimized fuel injection was experimentally investigated and numerically simulated. The experiments were carried out on a production SI engine which has a port fuel injection (PFI) system. The previous port electronic fuel injection system was modified and the technique of double-pulse fuel injection (DFI) was employed. By regulating injection timings and proportions of DFI, the air-fuel mixture stratification was significantly improved and the expected lean burn was implemented. The experimental results showed that the reduction of fuel consumption with DFI could be above 10 per cent over quite a wide load range, compared to single fuel injection. With optimized fuel injection timings and double-pulse proportions, the ideal engine performance and emissions can be achieved with a two to three times higher air-fuel ratio (AFR) than single fuel injection. With numerical simulation, the effects of mixture stratification formed by different fuel injection amounts and timings were analysed using a phenomenological model. The mixture in the cylinder was divided into different regions that distribute spherically around the spark plug and consist of a central region of stoichiometric air-fuel mixture and a gradually leaner outside region. Simulation results demonstrated that the improvements in fuel economy and emissions with DFI were mainly attributed to increased stratification zones and a reduced AFR gradient in the stratification zones.

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30

Egorushkin, E. A., A. V. Shabanov, and A. A. Shabanov. "Ignition of poor fuel-air mixtures in gasoline-driven ICEs - problems, solutions." Izvestiya MGTU MAMI 11, no. 2 (June 15, 2017): 72–77. http://dx.doi.org/10.17816/2074-0530-66923.

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The article deals with the development of technologies in the field of improving the organization of the combustion process in internal combustion engines in order to solve the problem of protecting the environment and increasing the efficiency of fuel resources. The carried out analysis has shown the increased interest of researchers and automotive experts in the problem of ignition of poor mixtures in ICE by the method of fuel-air charge separation in the combustion chamber. The directions of intensification of combustion of poor mixtures in internal combustion engines are considered due to application of various methods of fuel-air charge separation in the combustion chamber of internal combustion engines. Combustion of poor mixtures ensures low emissions of harmful substances with exhaust gases of the internal combustion engine and improved fuel economy. The advantage of an internal combustion engine using poor fuel-air mixtures is its operation with little or no charge throttling at the inlet. At the same time, fuel consumption and, correspondingly, CO2 emissions are reduced to 25%. Low concentrations of harmful emissions also reduce the efficiency requirements of the neutralizer. The process of combustion of poor mixtures is carried out due to the technologies of direct electronic fuel injection into the combustion chamber under high pressure and catalytic neutralization of combustion products of poor mixtures. Effective combustion of fuel-air mixtures is achieved with an excess air factor of less than 1.7. The article also contains the results of tests of the prechamber-flare internal combustion engine, which showed the possibility of using qualitative engine power regulation due to work on poor mixtures and a significant reduction in emissions of harmful substances with exhaust gases. It is shown that the use of an electronic ignition system with an increased discharge energy and a system of homogeneous mixture formation leads to an intensification of combustion of poor mixtures in the internal combustion engine, and allows the engine to operate at superhigh mixtures with an air excess factor of 3.5 with stable combustion of fuel-air mixtures.

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31

Green, R. K., and C. C. Zavier. "Charge Stratification in a Spark Ignition Engine." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 206, no. 1 (February 1992): 59–64. http://dx.doi.org/10.1243/pime_proc_1992_206_008_02.

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The effect of charge stratification on lean mixture combustion in a Ricardo E6 single-cylinder four-stroke reciprocating engine has been investigated. To do this, a commercially available spark plug was modified so that small amounts of pure methane gas could be injected, via the spark electrode, into a lean mixture within the combustion chamber prior to ignition. The effect on engine performance of variations in the methane injection process were analysed. The research has led to the following conclusions: 1. The lean limit of a homogeneous air-fuel mixture is extended by this relatively simple charge stratification process. 2. The effectiveness of charge stratification is most noticeable at lean air-fuel ratios in terms of improved brake specific fuel consumption. 3. Unburnt hydrocarbon emission levels are higher with the stratified charge process when compared to normal homogeneous mixture operation. 4. Carbon monoxide levels with stratified charge combustion are almost the same or a little lower than normal operation at the leanest air-fuel ratios.

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32

KOVAR, Zdenek, Celestyn SCHOLZ, Stanislav BEROUN, Milan NYDRLE, Hynek DROZDA, Josef BLAZEK, and Miroslav SVOBODA. "Hydrogen piston engines: R&D, experiences." Combustion Engines 125, no. 2 (May 1, 2006): 28–36. http://dx.doi.org/10.19206/ce-117350.

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Results of experimental works on hydrogen testing engines are presented in the paper: mixture forming, burning of air-hydrogen mixtures with different air/fuel ratio, NOx production, power parameters. The R&D works were realized on a single cylinder test engine (both natural aspirated and supercharged) and on a turbocharged six cylinder test engine as well.

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33

Jairam, Karthick, Feroskhan Mohammed Musthafa, Kishorre Annanth Vijayan, and Manimaran Renganathan. "Computational investigations on port injected DEE in a biogas inducted HCCI engine." International Journal for Simulation and Multidisciplinary Design Optimization 12 (2021): 9. http://dx.doi.org/10.1051/smdo/2021010.

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Owing to global climate change and atmospheric pollution, several automobile manufacturing companies look for homogeneously charged engines to satisfy strict emission levels. In the present work, computational fluid dynamics (CFD) investigations have been carried out to showcase the homogeneity of air-fuel mixture formation by port fuel injection and manifold fuel injection of a Biogas-Diethyl Ether (DEE) homogeneous charge compression engine (HCCI). The distributions of equivalence ratio based on fuel and the total air-fuel mixture is formulated and found to be in close agreement with the literature. Earlier investigations have shown that the use of biogas as a single fuel causes lower power output compared to other alternative fuels. Hence the present study is planned to use biogas with DEE as an ignition improver via fuel injection systems to find the best suitable fuel injection system. In the mesh independent study, port injection mode is found to perform better against the manifold injection mode when compared with the homogeneity factor. Iso-volumes of excess-air ratio based on biogas, diethyl ether and other variables such as the density, turbulent kinetic energy, turbulent dissipation rate of air-fuel mixture influencing the homogeneity and equivalence ratio are studied for better in-cylinder distribution under the port injection mode.

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34

Narcizo, G. G., and D. A. Miranda. "NUMERICAL ANALYSIS OF THE AIR-FUEL MIXTURE IN INDIRECT AND DIRECT INJECTION OF FOUR-STROKE ENGINES." Revista de Engenharia Térmica 18, no. 2 (December 16, 2019): 89. http://dx.doi.org/10.5380/reterm.v18i2.70799.

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The quality of the air-fuel mixture in internal combustion engines directly affects the combustion efficiency, therefore a good design of the combustion chamber combined with the correct fuel injection system, can provide a better use of this mixture and increase the efficiency of the engine. Considering these aspects, this scholarly work presents a comparative study of the indirect injection system and direct fuel injection, analyzing the way the mixture behaves in these two conditions. For this, the Ansys Fluent simulation software was used, in which were applied computational fluid dynamics simulations of the air-fuel mixture. The objective of this scholarly work is to contribute to the development of the injection systems, enabling the improvement of new studies and developments of new nozzle models can be performed.

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35

Huang, Q., B. Jones, and N. J. Leighton. "Hybrid Solid State Fluidic Technique in Engine Fuel Injection Systems." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 207, no. 1 (January 1993): 35–41. http://dx.doi.org/10.1243/pime_proc_1993_207_157_02.

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This paper describes a multi-point fuel injection system utilizing fiuidic devices as fuel injector stages for spark ignition engines. The novel fuel injector unit consists of no-moving-part fluidic devices controlled by a solenoid valve interface and unique air/fuel mixing nozzles for good fuel atomization. The results of laboratory tests show that the fluidic device stage has a fast dynamic response and its on/off switching delay to the control flow signal is within 1 ms. A balanced fuel distribution at the four fluidic injector stages (for a four-cylinder engine) and well-atomized air/fuel mixture at the mixing nozzles were obtained from this injection system. The engine tests show that this fuel injection system provides an extended lean limit of the air/fuel mixture, 7 per cent improvement in fuel economy and 10 per cent reduction in hydrocarbon (HC) emissions compared with a base-line carburetted fuelling system due to the improved fuel distribution and air/fuel mixing quality by the multi-point fluidic injection system.

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36

Yuniarto Agus Winoko, Santoso, and Khambali. "PENGARUH SUHU BAHAN BAKAR TERHADAP EMISI GAS BUANG PADA MESIN BENSIN 1800 cc." Jurnal Teknik Ilmu Dan Aplikasi 9, no. 2 (April 28, 2021): 4–7. http://dx.doi.org/10.33795/jtia.v9i2.24.

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The perfect combustion process can occur if the high compression pressure, proper ignition time, and suitable fuel air mixture. Suitable fuel air mixture can be obtained by heating the fuel to reduce its viscosity so the mixture is more homogeneous. Fuel heating can be done in various ways, such as by utilizing the heat of radiator water coming out of the engine. The purpose of the study is determine effect of the fuel heating to exhaust emission of gasoline engine 1800cc. The study uses experimental with the variable used pertamax with temperature 40°, 50°, 60°, and 70°. The dependent variable in the study is exhaust emission of gasoline engine. The results of the study indicate that fuel heating affects exhaust emissions. Temperature that affects the exhaust gas emissions at 60o C with the use of pertamax fuel.

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37

Soroka, B. S., and N. V. Vorobyov. "Efficiency of the Use of Humidified Gas Fuel and Oxidizing Mixture." ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, no. 6 (November 29, 2019): 547–64. http://dx.doi.org/10.21122/1029-7448-2019-62-6-547-564.

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The influence of hydration of the components of combustion (air-oxidizer and – in some cases – fuel) including hydration in the conditions of substitution of natural gas by alternative gas fuels, viz. by coke blast furnace mixture and natural blast furnace mixture – on energy efficiency of the use of different fuels has been determined. Calculations of fuel saving for substitution of natural gas (NG) by wet process gas (blast furnace gas (BFG), coke gas (CG), their mixtures) were performed taking into account real technological parameters (on the example of a specific metallurgical plant). All the calculations were performed within the framework of the author’s methodology on fuel substitution grounded on the 1st and the 2nd laws of thermodynamics. The analysis of possibility for saving or overspending NG is performed in the conditions of preservation of the flow of the used total enthalpy (as the main requirement of the methodology that had been proposed) and of taking into account the corresponding efficiency of fuel use. The calculation of the required heat flow of natural gas combustion depending on the content of wet blast furnace gas in NG + BFG mixtures for the cases of NG substitution by process gases has been carried out. It is established that the presence of moisture in the fuel-oxidation mixture always reduces the efficiency of the combustion chamber or the energy process and the unit. In order to increase the efficiency of a high-temperature furnace (boiler), it is necessary to provide heating of combustion components when utilizing the heat of the outgoing combustion products. It is shown that the efficiency of the fuel-using system can be significantly increased when the potential (excess total enthalpy) of the working fluid (combustion products) is activated. There are additiоnal benefits due to the fact that the existing heat of products of combustion with humid air in a full range of temperatures – from the theoretical combustion temperature to ambient temperature under conditions of equilibrium, including account of the heat of condensation – increases with increasing moisture content of the initial components of combustion, viz. air-oxidizer and/or fuel gas.

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38

Frolov, S. M., V. I. Zvegintsev, V. S. Aksenov, I. V. Bilera, M. V. Kazachenko, I. O. Shamshin, P. A. Gusev, and M. S. Belotserkovskaya. "Deflagration-to-detonation transition in air mixtures of polypropylene pyrolysis products." Доклады Академии наук 488, no. 2 (September 24, 2019): 162–66. http://dx.doi.org/10.31857/s0869-56524882162-166.

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A new method for determining the detonability of fuel is proposed based on the measured values of the detonation run-up distance and time in the standard pulsed detonation tube (PDT). Granulated polypropylene (GP) was used as a fuel. A test bench with the PDT and a gas generator was designed and manufactured for the preparation of the GP pyrolysis products at a decomposition temperature of up to 800 °C. Experiments on deflagration-to-detonation transition in air mixtures of pyrolysis products of the GP showed that such mixtures exhibit detonability close to that of liquefied hydrocarbon gas (LPG) of the propane-butane automobile brand in a stoichiometric mixture with air under normal conditions.

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39

Filipovic, Ivan, Boran Pikula, and Goran Kepnik. "Impact of physical properties of mixture of diesel and biodiesel fuels on hydrodynamic characteristics of fuel injection system." Thermal Science 18, no. 1 (2014): 143–53. http://dx.doi.org/10.2298/tsci130513010f.

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One of the alternative fuels, originating from renewable sources, is biodiesel fuel, which is introduced in diesel engines without major construction modifications on the engine. Biodiesel fuel, by its physical and chemical properties, is different from diesel fuel. Therefore, it is expected that by the application of a biodiesel fuel, the characteristic parameters of the injection system will change. These parameters have a direct impact on the process of fuel dispersion into the engine cylinder, and mixing with the air, which results in an impact on the quality of the combustion process. Method of preparation of the air-fuel mixture and the quality of the combustion process directly affect the efficiency of the engine and the level of pollutant emissions in the exhaust gas, which today is the most important criterion for assessing the quality of the engine. The paper presents a detailed analysis of the influence of physical properties of a mixture of diesel and biodiesel fuels on the output characteristics of the fuel injection system. The following parameters are shown: injection pressure, injection rate, the beginning and duration of injection, transformation of potential into kinetic energy of fuel and increase of energy losses in fuel injection system of various mixtures of diesel and biodiesel fuels. For the analysis of the results a self-developed computer program was used to simulate the injection process in the system. Computational results are verified using the experiment, for a few mixtures of diesel and biodiesel fuels. This paper presents the verification results for diesel fuel and biodiesel fuel in particular.

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40

Murray, E. Perry, S. J. Harris, J. Liu, and S. A. Barnett. "Direct Solid Oxide Fuel Cell Operation Using a Dimethyl Ether/Air Fuel Mixture." Electrochemical and Solid-State Letters 8, no. 10 (2005): A531. http://dx.doi.org/10.1149/1.2033622.

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41

Ishii, Eiji, Yoshihiro Sukegawa, Hiroshi Yamada, and Yoshihito Yasukawa. "414 Simulation of Fuel Spray with Air/Fuel Mixture Using A Particle Method." Proceedings of The Computational Mechanics Conference 2008.21 (2008): 195–96. http://dx.doi.org/10.1299/jsmecmd.2008.21.195.

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42

ZENIYA, Yoji, and Tomoyasu AIHARA. "Molecular Dynamics Study of Vaporization Behavior of Hydrocarbon Fuel in Air-Fuel Mixture." Proceedings of Mechanical Engineering Congress, Japan 2016 (2016): J0540405. http://dx.doi.org/10.1299/jsmemecj.2016.j0540405.

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43

Anggono, Willyanto, I. N. G. Wardana, M. Lawes, K. J. Hughes, Slamet Wahyudi, and Nurkholis Hamidi. "Laminar Burning Velocity and Flammability Characteristics of Biogas in Spark Ignited Premix Combustion at Reduced Pressure." Applied Mechanics and Materials 376 (August 2013): 79–85. http://dx.doi.org/10.4028/www.scientific.net/amm.376.79.

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Biogas as a “Powergas” is an alternative fuel produced in digestion facilities, that is sustainable and renewable. Based on chemical analysis, the composition of the biogas produced in East Java is 66.4% methane, 30.6% carbon dioxide and 3% nitrogen. Methane is a flammable gas, whereas, nitrogen and carbon dioxide are inhibitors. Given it has a different composition to traditional fuels, a fundamental study of biogas flame propagation characteristics is desirable to quantify this important fuel property. Spherically expanding flames propagating at constant pressure are employed to measure the laminar burning velocity and flammability characteristics as mixture function of the mixture composition. These important parameters were measured using a photographic technique in a high pressure fan-stirred bomb. The characteristics of biogas-air flames were initially studied at reduced pressure and at various equivalence ratios from the lower flammable limit to the upper flammable limit. The results were compared with those from biogas-air flames at atmospheric pressure. Based on this experimental investigation, the laminar burning velocities of biogas-air mixtures at reduced pressure were 0.218 m/s for ϕ=0.75, 0.246 m/s for ϕ=0.80 and 0.269 m/s for ϕ=0.85 respectively and only for these biogas mixtures propagated at reduced pressure. At the same equivalence ratio (ϕ), the laminar burning velocities of the biogas-air mixtures at reduced pressure are higher than those at atmospheric pressure. The flammable region of biogas became narrower by reducing initial pressure. The dilution effect is stronger at reduced pressure. Therefore, the flammable composition mixture areas of biogas-air mixtures are more limited at reduced pressure than those at atmospheric pressure.

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44

Jamrozik, A., and W. Tutak. "Theoretical analysis of air-fuel mixture formation in the combustion chambers of the gas engine with two-stage combustion system." Bulletin of the Polish Academy of Sciences Technical Sciences 62, no. 4 (December 1, 2014): 779–90. http://dx.doi.org/10.2478/bpasts-2014-0085.

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Abstract The results of theoretical analysis of a mixture formation process during the compression stroke in a prechamber of the IC (internal combustion) gas engine with the stratified mixtures two-stage combustion system were presented in the paper. The course of excess air-fuel ratio changes in prechamber at ignition time λkz in function of degree of the mixture condensation during the compression stroke φ expressing quotient of a temporary cylinder and prechamber volume and maximal value of the volume were estimated. Research concerning λkz sensitivity on changes of rich combustible mixture composition delivered to the prechamber by the additional fuel supply system λko, mixture composition in cylinder _c and degree of filling a prechamber with the rich combustible mixture ξ were performed. According to numerical calculations it was proved that the real gas engine with the two stage combustion system at equal degree requires exact regulation of the three analysed values.

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45

Saijyo, K., T. Kojima, and K. Nishiwaki. "Computational fluid dynamics analysis of the effect of mixture heterogeneity on combustion process in a premixed charge compression ignition engine." International Journal of Engine Research 6, no. 5 (October 1, 2005): 487–95. http://dx.doi.org/10.1243/146808705x30585.

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We analyzed the interrelationships between mixture heterogeneity and reaction in a premixed charge compression ignition (PCCI) combustion, using large eddy simulation (LES) in conjunction with a reaction kinetics model. The aim of this analysis is to find the statistical characteristics of the mixture heterogeneity in a turbulent flowfield for moderating the PCCI combustion and for increasing an output limit, which is restricted by a severe knock. Several different initial conditions of heterogeneity of an air-fuel or air-fuel-EGR gas mixture were given at the intake valve closing time by a new method, which generated statistically reasonable turbulent fluctuations in both velocity and fuel mass fraction fields. The autoignition and combustion behaviours were analysed for several different sets of the r.m.s. and the length scale of the fluctuations in the fuel mass fraction. The analyses show that the combination of a larger r.m.s. value and a longer-length scale of the fluctuations in fuel mass fraction is effective to slow the combustion in a hot flame reaction phase and to avoid knocking. The analytical results also show that the heterogeneous distribution of an EGR gas has a considerable effect in making the combustion slower, even when a fuel-air mixture is homogeneous.

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46

Grosshandler, W. L., and E. M. Thurlow. "Generalized State-Property Relations for Nonluminous Flame Absorption Coefficients." Journal of Heat Transfer 114, no. 1 (February 1, 1992): 243–49. http://dx.doi.org/10.1115/1.2911253.

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The work reported here simplifies computing the local Planck-mean absorption coefficient in nonluminous flames as a function of the mixture fraction and fuel composition. Equilibrium is assumed for fuel/air mixtures up to the point where carbon is predicted to condense, beyond which the gaseous products are assumed to be frozen and to be diluted with cold fuel. The resulting algebraic expressions are suitable for inclusion in any turbulent or laminar diffusion flame model predicated on single-step chemistry. The method accounts for the nongray nature of the gaseous combustion products and their variation in concentration and temperature with mixture fraction, at a computational penalty little more than that for estimating variable fluid properties. Nonluminous flames (in air) of H2, CO, CH3OH, CH4 and lean regions of fuels with the general form CxHyOz can be modeled satisfactorily. The effects of pressure-pathlength and heat loss on the absorption coefficient are addressed.

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47

Ladommatos, N., and D. Rose. "Monitoring of the Mixture Strength in the Cylinders of a Port-Injected Gasoline Engine During Transient Operation." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 209, no. 2 (April 1995): 127–34. http://dx.doi.org/10.1243/pime_proc_1995_209_193_02.

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A method has been developed which allows monitoring of the air—fuel ratio within the cylinders of a running gasoline engine. The method, which uses a fast-response flame ionization detector (FID), is capable of resolving the air—fuel ratio of individual consecutive engine cycles This method was used to monitor the air—fuel ratio in a port-injected gasoline engine during fast throttle opening. The results obtained show that for a handful of engine cycles the air—fuel ratio departs from the stoichiometric Value. Using additional measurements of the air and fuel supplied to the engine, it was possible to investigate the accumulation of fuel on the inlet port walls of the engine during the throttle opening. The results presented in this paper suggest that the departure of the air—fuel ratio from the stoichiometric value is shorter lived than that recorded by other investigators who used exhaust oxygen sensors for their tests.

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48

Ishiyama, T., M. Shioji, and T. Lhara. "Analysis of ignition processes in a fuel spray using an ignition model including turbulent mixing and reduced chemical kinetics." International Journal of Engine Research 4, no. 3 (June 1, 2003): 155–62. http://dx.doi.org/10.1243/146808703322223298.

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In order to clarify the mechanism of fuel spray ignition, an ignition model was developed employing a stochastic turbulent mixing model and a quasi-global chemical kinetics model. Using this model, histories of heterogeneity in temperature and equivalence ratio of fuel/air mixtures were analysed. At low initial ambient temperatures, exothermic reactions begin in lean mixtures with equivalence ratios in a very narrow range. On the other hand, at higher air temperatures, mixtures with a variety of equivalence ratios ignite. This phenomenon can be explained by the dependency of mixture reactivity on the equivalence ratio and temperature. Based on these results, a discussion is given on the similarities and differences in the temperature dependency of ignition delays between sprays and homogeneous mixtures.

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49

Hershan, D. G. "EFFECT OF COMPOSITION OF FUEL CONTAINING BUTANOL ON WORKING PROCESS PARAMETERS OF DIESEL ENGINE." Science & Technique 16, no. 3 (May 26, 2017): 225–31. http://dx.doi.org/10.21122/2227-1031-2017-16-3-225-231.

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Computational researches the effect of composition of fuel containing butanol on working process parameters of 4ЧН 11/12,5 diesel engine on the external speed characteristic have been conducted. Nominal power is 140 kW at engine speed 2300 min–1. The engine is equipped with gas turbine pressure charging with intercooling of charging air, accumulator-type fuel-handling system. Calculations of the working process have been made in accordance with the developed computer program and models. Investigations have been carried out in two stages: without any changes in regulation of fuel-handling system and with cyclic fuel delivery that ensure such value of excess air factor at various operational modes which corresponds to the operation with diesel fuel. All the obtained results have been analyzed in the paper. The paper shows changes in mean indicated pressure, specific indicated fuel consumption, indicated efficiency, specific nitrogen oxides emissions for various modes in question while using 5, 10, 15, 20, 25 and 30 % mixture of diesel fuel with butanol. Dependences of parameters pertaining to diesel operation have been determined according to external speed characteristic for various mixtures and the obtained data make it possible to justify parameters of the fuel-handling system. It has been recommended to use a diesel fuel-butanol mixture containing 15 % of butanol without any changes in regulating and design engine parameters. It has been revealed that in order to improve parameters of the engine operational process mixture composition must be changed while changing the operational mode. An injector nozzle with a compound needle for the fuel-handling system has been developed and it allows to change fuel composition according to engine operational mode.

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Du, Bingxuan, and Zhenfeng Zhao. "Experimental Investigation on the Effects of Injection Parameters on the Air-Assisted Diesel Spray Characteristics." International Journal of Aerospace Engineering 2022 (February 28, 2022): 1–21. http://dx.doi.org/10.1155/2022/6814732.

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The air-assisted fuel injection (AAFI) system may be installed in the spark ignition aviation piston engine for the atomization of heavy fuels. However, studies on the effects of injection parameters on the spray characteristics are insufficient, which affects the improvement of AAFI engine performance. In this study, air-assisted diesel spray characteristics are investigated experimentally using a high-speed backlit imaging technique. The effects of main air-assisted injection control parameters such as fuel injection pressure, fuel temperature, and fuel injection duration on the spray characteristics are examined. The results show that spray shape changes from “spindle” to “cone” with an increase in fuel injection pressure. As the fuel injection pressure increases to 1.0 MPa, both the spray penetration and spray width increase significantly. “Protrusions” appear on the spray edge at high fuel temperatures. When the fuel temperature drops to 268 K, the spray penetration and spray width increase slightly. The spray shrinks significantly in both the axial and radial directions with an increase in fuel injection duration. Key parameters that directly affect air-assisted spray characteristics include the difference between the fuel-air mixture injection pressure and the ambient pressure, the density of fuel-air mixture in the air-assisted injector premixed chamber, and the kinetic energy density of the fuel. The former two parameters affect the spray penetration while the latter affects the spray width. The study is beneficial for the design of AAFI engines.

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