Journal articles: 'Fuel jets'

1

Pickett, L. M., and D. L. Siebers. "Soot Formation in Diesel Fuel Jets Near the Lift-Off Length." International Journal of Engine Research 7, no. 2 (April 1, 2006): 103–30. http://dx.doi.org/10.1243/146808705x57793.

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Soot formation in the region downstream of the lift-off length of diesel fuel jets was investigated in an optically accessible constant-volume combustion vessel under quiescent-type diesel engine conditions. Planar laser-induced incandescence and line-of-sight laser extinction were used to determine the location of the first soot formation during mixing-controlled combustion. OH chemiluminescence imaging was used to determine the location of high-heat-release reactions relative to the soot-forming region. The primary parameters varied in the experiments were the sooting propensity of the fuel and the amount of fuel-air premixing that occurs upstream of the lift-off length. The fuels considered in order of increasing sooting propensity were: an oxygenated fuel blend (T70), a blend of diesel cetane-number reference fuels (CN80), and a #2 diesel fuel (D2). Fuel-air mixing upstream of the lift-off length was varied by changing ambient gas and injector conditions, which varied either the lift-off length or the air entrainment rate into the fuel jet relative to the fuel injection rate. Results show that soot formation starts at a finite distance downstream of the lift-off length and that the spatial location of soot formation depends on the fuel type and operating conditions. The distance from the lift-off length to the location of the first soot formation increases as the fuel sooting propensity decreases (i.e. in the order D2 < CN80 < T70). At the baseline operating conditions, the most upstream soot formation occurs at the edges of the jet for D2 and CN80, while for T70 the soot formation is confined to the jet central region. When conditions are varied to produce enhanced fuel-air mixing upstream of the lift-off length in D2 fuel jets, the initial soot formation shifts towards the fuel jet centre and eventually no soot is formed. For all experimental conditions, the observed location of soot formation relative to the heat-release location (lift-off) suggests that soot formation occurs in a mixture of combustion products originating from partially premixed reactions and a diffusion flame. The results also imply that soot precursor formation rates depend strongly on fuel type in the region between the lift-off length and the first soot formation.

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2

Pianthong, K., A. Matthujak, K. Takayama, T. Saito, and Brian E. Milton. "VISUALIZATION OF SUPERSONIC LIQUID FUEL JETS." Journal of Flow Visualization and Image Processing 13, no. 3 (2006): 217–42. http://dx.doi.org/10.1615/jflowvisimageproc.v13.i3.20.

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3

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, no. 1 (January 1, 1998): 17–23. http://dx.doi.org/10.1115/1.2818073.

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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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4

Hill, Philip G., and Patric Ouellette. "Transient Turbulent Gaseous Fuel Jets for Diesel Engines." Journal of Fluids Engineering 121, no. 1 (March 1, 1999): 93–101. http://dx.doi.org/10.1115/1.2822018.

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Existing data on transient turbulent jet injection in to large chambers demonstrates self-similar behavior under a wide range of conditions including compressibility, thermal and species diffusion, and nozzle under expansion. The Jet penetration distance well downstream of the virtual origin is proportional to the square root of the time and the fourth root of the ratio of nozzle exit momentum flow rate to chamber density. The constant of proportionality has been evaluated by invoking the concept of Turner that the flow can be modeled as a steady jet headed by a spherical vortex. Using incompressible transient jet observations to determine the asymptotically constant ratio of maximum jet width to penetration distance, and the steady jet entrainment results of Ricou and Spalding, it is shown that the penetration constant is 3 ± 0.1. This value is shown to hold for compressible flows also, with substantial thermal and species diffusion, and even with transient jets from highly under-expanded in which, as in diesel engine chambers with gaseous fuel injection, the jet is directed at a small angle to one wall of the chamber. In these tests, with under expanded nozzles. Observations of transient jet injection have been made in a chamber in which, as in diesel engine chambers with gaseous fuel injection, the jet is directed at a small angle to one wall of the chamber. In these tests, with under-expanded nozzles it was found that at high nozzle pressure ratios, depending on the jet injection angle, the jet penetration can be consistent with a penetration constant of 3. At low pressure ratios the presence of the wall noticeably retards the penetration of the jet.

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5

Peleowo, Adedamola Najeem. "The Effect of Nozzle Breakaway Pressure on the Spray Pattern Formed." Applied Mechanics and Materials 248 (December 2012): 173–78. http://dx.doi.org/10.4028/www.scientific.net/amm.248.173.

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The main function of a fuel injector nozzle is to break fuels into droplets, form the spray pattern, and propel the droplets into a combustion chamber. The amount of spray volume at a given operating pressure, the travel speed, and spacing between the jets of fuel can also be determined by the nozzle. In fuel injection, the smallest possible droplet size is desired for the most flow. This work presents an opportunity to use the Schlieren arrangement as a visualization method to view the flow of fuel from a three-hole fuel injector nozzle which cannot be seen by the naked eye. The jet flow of diesel Fuel was investigated by Schlieren photography. A test rig was designed and constructed to accommodate the nozzle; optical mirrors were arranged according to Schlieren specifications in order to allow the jet to be photographed. The breakaway pressure of the nozzle was varied between 60bar to 80bar. Each hole of the nozzle is 0.26mm in diameter and 120° apart; the third jet could not be seen from the images because the camera took x-y dimension images. The spray pattern observed from the two dimensional images of the jets developed were seen to be well dispersed. Su et al [3] found that emissions could be reduced in diesel engines if the injector nozzle produces smaller and more dispersed droplets.

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6

Neal, Nicholas, and David Rothamer. "Evolving one-dimensional transient jet modeling by integrating jet breakup physics." International Journal of Engine Research 18, no. 9 (February 1, 2017): 909–29. http://dx.doi.org/10.1177/1468087416688119.

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High-speed optical measurements of unsteady liquid fuel jets under engine-like conditions have shown that the initial penetration of the jets does not follow the behavior predicted by previously introduced one-dimensional jet models based on gas-jet principles. The experimental data indicate that the transient jet penetration velocity is initially controlled by the jet exit velocity, transitioning to gas-jet like mixing-dominated penetration further downstream. This behavior is consistent with the common description of high-pressure fuel jets as containing a liquid core surrounded by entrained gas and fuel droplets. In this paper, a new one-dimensional modeling methodology is introduced that couples the transport equations for the evolution of the liquid core of the jet and the surrounding sheath of droplets resulting from breakup. This allows for the penetration of the jet to be initially governed by the liquid core, which is relatively unaffected by the ambient gas, transitioning to spray penetration dominated by the entrained ambient gas. The model also provides a defined jet centerline velocity, which allows for the shape of the radial profiles of fuel velocity and fuel volume fraction to be solved for directly, without the need for a steady-jet assumption, as was used in previous one-dimensional models. This change removes the need for a constant momentum flux assumption, improving the transient nature of the model. The results of the model are validated against the aforementioned optical transient jet measurements. The model and all associated experimental data have been made available for use at rothamer.erc.wisc.edu/dlp .

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7

Crocker, D. S., and C. E. Smith. "Numerical Investigation of Enhanced Dilution Zone Mixing in a Reverse Flow Gas Turbine Combustor." Journal of Engineering for Gas Turbines and Power 117, no. 2 (April 1, 1995): 272–81. http://dx.doi.org/10.1115/1.2814091.

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An advanced method for dilution zone mixing in a reverse flow gas turbine combustor was numerically investigated. For long mixing lengths associated with reverse flow combustors (X/H > 2.0), pattern factor was found to be mainly driven by nozzle-to-nozzle fuel flow and/or circumferential airflow variations; conventional radially injected dilution jets could not effectively mix out circumferential nonuniformities. To enhance circumferential mixing, dilution jets were angled to produce a high circumferential (swirl) velocity component. The jets on the outer liner were angled in one direction while the jets on the inner liner were angled in the opposite direction, thus enhancing turbulent shear at the expense of jet penetration. Three-dimensional CFD calculations were performed on a three-nozzle (90 deg) sector, with different fuel flow from each nozzle (90, 100, and 110 percent of design fuel flow). The computations showed that the optimum configuration of angled jets reduced the pattern factor by 60 percent compared to an existing conventional dilution hole configuration. The radial average temperature profile was adequately controlled by the inner-to-outer liner dilution flow split.

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8

Hesman, Tina. "Coal: The Cool Fuel for Future Jets." Science News 157, no. 15 (April 8, 2000): 230. http://dx.doi.org/10.2307/4012523.

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9

Ni, T. Q., and L. A. Melton. "Fuel Equivalence Ratio Imaging for Methane Jets." Applied Spectroscopy 47, no. 6 (June 1993): 773–81. http://dx.doi.org/10.1366/0003702934066910.

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A 2-D fuel/oxygen equivalence ratio imaging system has been developed. The technique exploits the efficient quenching of the fluorescence of organic molecules by molecular oxygen in order to determine the fuel and oxygen partial pressures simultaneously. Following pulsed planar laser excitation of fluoranthene—a specially selected fluorescent dopant—two images of the fluorescence were recorded, with the second image being delayed by several nanoseconds. Use of a rapid lifetime determination algorithm yielded first a fluorescence lifetime image, and subsequently, with the assumption of Stern-Volmer quenching, an intensity image corrected for quenching. Images of the air pressure, fuel pressure, and the equivalence ratio were obtained. The technique, which uses dual gated intensifiers coupled to a sensitive CCD camera, requires only two integrated fluorescence intensities to calculate the fluorescence lifetime accurately. In the current work, images of the turbulence-induced mixing of a methane jet into quiescent air are displayed. Images can also be obtained in flames, but the analysis of the data is uncertain because the fluorescence lifetime of fluoranthene is temperature dependent.

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10

Seitz, Franziska, Robert Schießl, and Detlev Markus. "Ignition by Hot Free Jets." Zeitschrift für Physikalische Chemie 231, no. 10 (October 26, 2017): 1737–71. http://dx.doi.org/10.1515/zpch-2016-0914.

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Abstract This paper describes some of our experimental studies on the re-ignition caused by jets of hot gas that interact with unburned fuel/air mixtures. The problem is approached from two complementary sides: On the one hand, phenomenological studies are conducted, which ask for the conditions under which a hot jet may cause ignition. A dedicated experiment is described which allows to create well-controlled exhaust gas jets and ambient conditions. In this experiment, parameters influencing the ignition process are varied, and the dependence of jet behavior on these parameters (i.e. pressure ratio, diameter and length of the gap through which the exhaust gas has to pass before getting into contact with ambient fuel/air) is studied. In particular, the frequency of a jet causing re-ignition in the ambient gas is studied. On the other hand, we also perform studies which are more “analytical” in nature. These attempt a more in-depth understanding, by first decomposing the hot jet ignition phenomenon into the underlying physical processes, and then studying these processes in isolation. This approach is applied to measurements of mixture fraction fields. First, non reacting isothermal variable density jets are studied. Here, the density of the gas mixture varies as to mimic the density of hot exhaust gas at varying temperatures. A laser-based non-intrusive method is introduced that allows to determine quantitative mixture fraction fields; although applied here to cold jets only, the method is also applicable to hot jets. The results show the effect of turbulence on the mixing field in and at the free jet, and allow to derive quantities that describe the statistics of the turbulent jet, like probability density functions (PDFs) and geometrical size of fluctuations.

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11

Uejima, Mitsuhiro, and Yoshiaki Onuma. "Studies on the Spontaneous Ignition of Fuel Gas Jets. 3rd Report, Comparison between the Ignition of Fuel Gas Jets and Fuel Sprays." Transactions of the Japan Society of Mechanical Engineers Series B 60, no. 576 (1994): 2924–30. http://dx.doi.org/10.1299/kikaib.60.2924.

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12

Gitan, Ali Ahmed, Rozli Zulkifli, Kamaruzaman Sopian, and Shahrir Abdullah. "Twin Pulsating Jets Impingement Heat Transfer for Fuel Preheating in Automotives." Applied Mechanics and Materials 663 (October 2014): 322–28. http://dx.doi.org/10.4028/www.scientific.net/amm.663.322.

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The problem of environmental pollution and depletion of fossil fuel can be reduced in automotives by using an alternative bio-fuel and improve the ignition process in engine. Both solutions need to use the fuel preheating technique. This work presents the idea of fuel preheating by using exhaust impingement on the fuel tank. Heat transfer between twin pulsating hot air jets and flat copper target was investigated as an application for preheating of automotive fuel to improve ignition process in the engine. The nozzle of 20 mm was used to produce air jet of Reynolds number, Re ≃ 5500 and a temperature of 54°C. The impinged target was imposed to still air surrounding at temperature of 24°C. Pulsating frequencies of 10-50 Hz were applied on air jets by using twin pulsating jet mechanism. The effect of pulsation frequency on heat transfer was measured using IR camera and heat flux-temperature micro foil sensor. The results obtained by both of these methods showed well agreement. Also, the results revealed significant influence of flow rate difference between steady and pulsating jet cases. In addition, the highest Nusselt number, Nu ≃ 7.2, was obtained at pulsation frequency of 20 Hz.

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13

Kaario, Ossi Tapani, Ville Vuorinen, Heikki Kahila, Hong G. Im, and Martti Larmi. "The effect of fuel on high velocity evaporating fuel sprays: Large-Eddy simulation of Spray A with various fuels." International Journal of Engine Research 21, no. 1 (June 19, 2019): 26–42. http://dx.doi.org/10.1177/1468087419854235.

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Lagrangian particle tracking and Large-Eddy simulation were used to assess the effect of different fuels on spray characteristics. In such a two-way coupled modeling scenario, spray momentum accelerates the gaseous phase into an intense, multiphase jet near the nozzle. To assess fuel property effects on liquid spray formation, the non-reacting Engine Combustion Network Spray A baseline condition was chosen as the reference case. The validated Spray A case was modified by replacing n-dodecane with diesel, methanol, dimethyl ether, or propane assuming 150 MPa injection pressure. The model features and performance for various fuels in the under-resolved near-nozzle region are discussed. The main findings of the paper are as follows. (1) We show that, in addition to the well-known liquid penetration [Formula: see text], and vapor penetration [Formula: see text], for all the investigated fuels, the modeled multiphase jets exhibit also a third length scale [Formula: see text], with discussed correspondence to a potential core part common to single phase jets. (2) As a characteristic feature of the present model, [Formula: see text] is noted to correlate linearly with [Formula: see text] and [Formula: see text] for all the fuels. (3) A separate sensitivity test on density variation indicated that the liquid density had a relatively minor role on [Formula: see text]. (4) Significant dependency between fuel oxygen content and the equivalence ratio [Formula: see text] distribution was observed. (5) Repeated simulations indicated injection-to-injection variations below 2% for [Formula: see text] and 4% for [Formula: see text]. In the absence of experimental and fully resolved numerical near-nozzle velocity data, the exact details of [Formula: see text] remain as an open question. In contrast, fuel property effects on spray development have been consistently explained herein.

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14

Bankston, C. P., L. H. Back, E. Y. Kwack, and A. J. Kelly. "Experimental Investigation of Electrostatic Dispersion and Combustion of Diesel Fuel Jets." Journal of Engineering for Gas Turbines and Power 110, no. 3 (July 1, 1988): 361–68. http://dx.doi.org/10.1115/1.3240130.

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An experimental study of electrostatically atomized and dispersed diesel fuel jets has been conducted. A new electrostatic injection technique has been utilized to generate continuous, stable fuel sprays at charge densities of 1.5–2.0 C/m3 of fluid. Model calculations show that such charge densities may enhance spray dispersion under diesel engine conditions. Fuel jets were injected into room temperature air at one atmosphere at flow rates of 0.25–1.0 cm3/s and delivery pressures of 100–400 kPa. Measured mean drop diameters were near 150 μm with 30 percent of the droplets being less than 100 μm in diameter at typical operating conditions. The electrical power required to generate these sprays was less than 10−6 times the chemical energy available from the fuel. The spray characteristics of an actual diesel engine injector were also studied. The results show considerable differences in spray characteristics between the diesel injector and electrostatic injection. Finally, ignition and stable combustion of electrostatically dispersed diesel fuel jets was achieved. The results show that electrostatic fuel injection can be achieved at practical flow rates, and that the characteristics of the jet breakup and dispersion have potential application to combustion systems.

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15

Azim, M. A. "Isothermal free jets in high-temperature surroundings." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, no. 8 (May 16, 2011): 1913–18. http://dx.doi.org/10.1177/0954406211401488.

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Two types of isothermal free jets, named positively and negatively buoyant, have been studied numerically to discern the effect of surrounding temperatures on their flow dynamics. Turbulence closure in those jets was achieved by standard k - ε model. The governing equations were solved using Implicit θ-Scheme and Tridiagonal Matrix Algorithm. Calculations were made for the jets having constant temperature at 20 °C and by varying surrounding temperatures from 20°C to 1000°C. It is clear that negatively buoyant jets but not the positively buoyant jets are nearly invariant to the change in surrounding temperatures compared to non-buoyant jet. Change in fluid dynamical behaviour of positively buoyant jets due to surrounding temperature change seems promising as it may offer the advantages of fuel jets in high-temperature air combustion.

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16

Owston, Rebecca, Vinicio Magi, and John Abraham. "Fuel-Air Mixing Characteristics of DI Hydrogen Jets." SAE International Journal of Engines 1, no. 1 (April 14, 2008): 693–712. http://dx.doi.org/10.4271/2008-01-1041.

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17

Zakrzewski, S., B. E. Milton, K. Pianthong, and M. Behnia. "Supersonic liquid fuel jets injected into quiescent air." International Journal of Heat and Fluid Flow 25, no. 5 (October 2004): 833–40. http://dx.doi.org/10.1016/j.ijheatfluidflow.2004.05.010.

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18

Kamal, MM. "Combustion via multiple pairs of opposing premixed flames with a cross-flow." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 231, no. 1 (October 7, 2016): 39–58. http://dx.doi.org/10.1177/0957650916673256.

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A cylindrical burner accommodating stoichiometric fuel–air mixture combustion via multiple pairs of opposing jets and a cross-flow provided heat intensification and duplication of the stagnation impact for extending the firing limits and maximizing the power density. Six pairs of circumferentially opposing stoichiometric mixture jets sustained bulk injection velocities as high as 21.8 m/s and were associated with NOx emissions of 22 ppm, while emissions of 10 ppm were recorded upon reaching a lean limit equivalence ratio of 0.59. A stoichiometric mixture jet issuing perpendicular to the opposing jets at a momentum flux ratio of 0.3 increased the turbulence production rates to the extent that increased the maximum bulk injection velocity to 28.3 m/s and reduced the NOx emissions to 17 ppm. Since the recirculation zones between the two stagnation centers got compressed by increasing the momentum flux ratio to 0.8, the corresponding residence time reduction decreased the NOx emissions to 12 ppm. As the cross-flow mixture was made fuel–lean, dilution of the stoichiometric mixture by the fuel–lean mixture combustion products made it possible to get NOx emissions of single digit ppm. Emissions of 9 ppm resulted from using the cross-flow fuel–lean mixture jet due to compromising the flame stability limit extension and the temperature reduction in the post flame region. Such emissions, in turn, decreased to 4 ppm as the momentum flux ratio increased to 1.7 at which the stoichiometric mixture flames shrank into their ports. A minimum NOx emission index of 0.27 g/kg fuel was thus obtained at a volumetric heat release of 50.4 MW/m3. The momentum flux ratio corresponding to merging the two stagnation zones was correlated with Reynolds and Froude numbers, the jets’ separation as well as the density and viscosity values pertaining to the lean and stoichiometric mixtures’ flame temperatures.

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19

Jasiński, Remigiusz, Paula Kurzawska, and Radosław Przysowa. "Characterization of Particle Emissions from a DGEN 380 Small Turbofan Fueled with ATJ Blends." Energies 14, no. 12 (June 8, 2021): 3368. http://dx.doi.org/10.3390/en14123368.

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The fine particulate matter (PM) emitted from jet aircraft poses a serious threat to the environment and human health which can be mitigated by using biofuels. This paper aims to quantify PM emissions from a small turbofan fueled with the alcohol to jet (ATJ) synthetic kerosene and its various blends (5%, 20%, and 30% of ATJ) with Jet A-1 fuel. Emissions from a turbofan engine (DGEN 380) with a high bypass ratio, applicable in small private jets, were studied. Among the four fuels tested, the PM-number emission index (EIN) was the lowest for the ATJ 30% blend. EIN for ATJ 30% dropped from 1.1 × 1017 to 4.7 × 1016 particles/kg of fuel. Burning alternative fuel blends reduced the particle mass emissions over the entire range of fuel flow by at least 117 mg/kg of fuel. The particles formed in the nucleation mechanism dominate PM emission, which is characteristic of jet engines. Thus, number-based particle size distributions (PSDs) exhibit a single mode log-normal distribution. The highest values of EIN were found for Jet A-1 neat compared to other fuels. The use of the ATJ additive did not cause significant changes in the size of the particles from nucleation mode. However, a magnitude reduction of nucleation mode was found with the increase in the ATJ ratio.

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20

Akselvoll, Knut, and Parviz Moin. "Large-eddy simulation of turbulent confined coannular jets." Journal of Fluid Mechanics 315 (May 25, 1996): 387–411. http://dx.doi.org/10.1017/s0022112096002479.

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Large-eddy simulation (LES) was used to study mixing of turbulent, coannular jets discharging into a sudden expansion. This geometry resembles that of a coaxial jet-combustor, and the goal of the calculation was to gain some insight into the phenomena leading to lean blow-out (LBO) in such combustion devices. This is a first step in a series of calculations, where the focus is on the fluid dynamical aspects of the mixing process in the combustion chamber. The effects of swirl, chemical reactions and heat release were not taken into account. Mixing of fuel and oxidizer was studied by tracking a passive scalar introduced in the central jet. The dynamic subgrid-scale (DM) model was used to model both the subgrid-scale stresses and the subgrid-scale scalar flux. The Reynolds number was 38000, based on the bulk velocity and diameter of the combustion chamber. Mean velocities and Reynolds stresses are in good agreement with experimental data. Animated results clearly show that intermittent pockets of fuel-rich fluid (from the central jet) are able to cross the annular jet, virtually undiluted, into the recirculation zone. Most of the fuel-rich fluid is, however, entrained into the recirculation zone near the instantaneous reattachment point. Fuel trapped in the recirculation zone is, for the most part, entrained back into the step shear layer close to the base of the burner.

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Connell, Terrence L., Grant A. Risha, Richard A. Yetter, and Benveniste Natan. "Hypergolic Ignition of Hydrogen Peroxide/Gel Fuel Impinging Jets." Journal of Propulsion and Power 34, no. 1 (January 2018): 182–88. http://dx.doi.org/10.2514/1.b36571.

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22

Lawn, C. J. "Lifted flames on fuel jets in co-flowing air." Progress in Energy and Combustion Science 35, no. 1 (February 2009): 1–30. http://dx.doi.org/10.1016/j.pecs.2008.06.003.

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23

Wu, P. K., K. A. Kirkendall, R. P. Fuller, M. R. Gruber, and A. S. Nejad. "Spray Trajectories of Liquid Fuel Jets in Subsonic Crossflows." International Journal of Fluid Mechanics Research 24, no. 1-3 (1997): 128–37. http://dx.doi.org/10.1615/interjfluidmechres.v24.i1-3.130.

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Azim, Mohammed A. "Effects of Efflux Velocity and Buoyancy on Fuel Jets." International Journal of Fluid Mechanics Research 41, no. 5 (2014): 430–39. http://dx.doi.org/10.1615/interjfluidmechres.v41.i5.40.

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Sadler, James D., Hui Li, and Brian M. Haines. "Magnetization around mix jets entering inertial confinement fusion fuel." Physics of Plasmas 27, no. 7 (July 2020): 072707. http://dx.doi.org/10.1063/5.0012959.

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Shi, Hong-Hui, and Kazuyoshi Takayama. "Generation of hypersonic liquid fuel jets accompanying self-combustion." Shock Waves 9, no. 5 (October 1, 1999): 327–32. http://dx.doi.org/10.1007/s001930050193.

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Nicolosi, Fabrizio, Salvatore Corcione, Vittorio Trifari, and Agostino De Marco. "Design and Optimization of a Large Turboprop Aircraft." Aerospace 8, no. 5 (May 6, 2021): 132. http://dx.doi.org/10.3390/aerospace8050132.

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This paper proposes a feasibility study concerning a large turboprop aircraft to be used as a lower environmental impact solution to current regional jets operated on short/medium hauls. An overview of this market scenario highlights that this segment is evenly shared between regional turboprop and jet aircraft. Although regional jets ensure a large operative flexibility, they are usually not optimized for short missions with a negative effect on block fuel and environmental impact. Conversely, turboprops represent a greener solution but with reduced passenger capacity and speed. Those aspects highlight a slot for a new turboprop platform coupling higher seat capacity, cruise speed and design range with a reduced fuel consumption. This platform should operate on those ranges where neither jet aircraft nor existing turboprops are optimized. This work compares three different solutions: a high-wing layout with under-wing engines installation and both two- and three-lifting-surface configurations with low-wing and tail tips-mounted engines. For each concept, a multi-disciplinary optimization was performed targeting the minimum block fuel on a 1600 NM mission. Optimum solutions were compared with both a regional jet such as the Airbus A220-300 operated on 1600 NM and with a jet aircraft specifically designed for this range.

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Mohabi, A., and M. Hejazi. "The Effect of Nozzle Configuration on Characteristics of Fluidic Excited Jets." Applied Mechanics and Materials 564 (June 2014): 269–74. http://dx.doi.org/10.4028/www.scientific.net/amm.564.269.

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Using fluidic self-excited jets increases the rate of fluid mixing and reduces fuel consumption in industry burners (torches) and combustion chambers. The geometry of such jets is an important factor for fluidic jet determination. This study is concerned with investigating the types of fluidic nozzles configuration. The effect of nozzle configuration types was studied on various parameters such as frequency, velocity profile, velocity decay rate, the half angle of jet spread, and entrainment ratio. Maximum frequency and excited oscillation amplitude of fluidic jets were observed in the original geometry configuration. Also, the maximum spread rate and minimum velocity profile were observed in this geometry. Velocity decay rate shows its maximum magnitude in the original geometry configuration. Turbulence intensity reaches its maximum value in this geometry without any internal nozzle, whereas it shows the minimum value at geometry with an additional wall along the internal nozzle. The maximum increase in the half angle of jet spread was seen in the original geometry configuration. In this geometry, entrainment ratio is less than one, while in the geometry to create steady jets, entrainment ratio is more than one.

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Li, Ziwan, Yixiang Yuan, Baoting Guo, V. L. Varsegov, and Jun Yao. "The Recirculation Zone Characteristics of the Circular Transverse Jet in Crossflow." Energies 13, no. 12 (June 22, 2020): 3224. http://dx.doi.org/10.3390/en13123224.

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Transverse jets in crossflow are widely used in energy systems, especially as dilution air jets, fuel/air mixers, and combustion equipment, and have received extensive attention and plenty of research. However, the studies of the circular transverse jet issued from a circular gap at the circumferential direction of a tube in crossflow are very limited. This paper studies a relatively new jet: the circular transverse jet. Firstly, numerical calculations are conducted under different turbulence models but with the same boundary conditions. By comparing the numerical results of different turbulence models with the existing experimental data, the turbulence model which is most suitable for the numerical calculation of the circular transverse jet is selected. Then, this turbulence model is used to calculate and analyze the flow field structure and its characteristics. It is found that due to the aerodynamic barrier effect of the high-velocity jet, a negative pressure zone is formed behind the jet trajectory; the existence of the negative pressure zone causes the formation of a vortex structure and a recirculation zone downstream the circular transverse jet; and the length/width ratio of the recirculation zone does not change with the changes of the crossflow and the jet parameters. It means that the recirculation zone is a fixed shape for a definite device. This would be fundamental references for the studying of fuel/air mixing characteristics and combustion efficiency when the circular transverse jet is used as a fuel/air mixer and stable combustion system.

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30

Milton, B. E., and K. Pianthong. "Pulsed, supersonic fuel jets—A review of their characteristics and potential for fuel injection." International Journal of Heat and Fluid Flow 26, no. 4 (August 2005): 656–71. http://dx.doi.org/10.1016/j.ijheatfluidflow.2005.03.002.

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31

Lotfiani, Amin, Shahram Khalilarya, and Samad Jafarmadar. "A semi-analytical model for the prediction of the behavior of turbulent coaxial gaseous jets." Thermal Science 17, no. 4 (2013): 1221–32. http://dx.doi.org/10.2298/tsci110701140l.

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In diffusion combustion systems, fuel and oxidizer (usually air) are admitted into the combustion chamber separately in the form of turbulent jets. Most often, fuel enters the furnace from a round nozzle and air is admitted through an annulus surrounding the central fuel nozzle. Momentum of the fuel and air jets is utilized for directing the flame and controlling the mixture formation which is typically the rate-limiting step of the combustion process. Hence the behavior of turbulent coaxial jets must be well understood prior to any detailed analysis of these systems. In this study, a set of relations is proposed to predict the behavior of turbulent coaxial gaseous jets using curve-fits to the computational fluid dynamics (CFD) solutions and the fluid flow governing equations as well as the ideal gas equation of state. A computer program is developed to implement the presented model. Results are compared with existing data and reasonable agreement is observed. According to the results, the presented model makes sufficiently accurate estimates of the flow and concentration fields in a very short time.

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32

Kochergin, Anatoly, and Valeeva Ksenia. "DETERMINATION OF THE NOISE POWER GENERATED BY THE POWDER SUPERSONIC JETS (SSJ)." Akustika 36, no. 36 (2020): 17–21. http://dx.doi.org/10.36336/akustika20203617.

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The paper analyzes the results of experimental studies of the parameters of acoustic fields generated by the jets of small-scale solid fuel rocket engines (SFRE). The field of isobars of sound pressure created by a supersonic jet (SSJ) is considered. To identify the most correct approach to determining the acoustic power of the SSJ, a numerical integration of the power of pressure pulsations along the length of the jet was performed.

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33

Lee, Pil Hyong, Chang Soo Park, and Sang Soon Hwang. "Formation of Oxygen-Fuel Wide Flame Using Impinging Jets Method." Transactions of the Korean Society of Mechanical Engineers - B 42, no. 1 (January 31, 2018): 1–7. http://dx.doi.org/10.3795/ksme-b.2018.42.1.001.

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34

Li, Ziwan, V. L. Varsegov, Xiaoming Shen, and Yixiang Yuan. "Study of Flame Stabilization Behavior in Supersonic Gaseous Fuel Jets." Russian Aeronautics 63, no. 3 (September 2020): 462–68. http://dx.doi.org/10.3103/s1068799820030125.

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35

Takahashi, Fumiaki, and Viswanath R. Katta. "Structure of propagating edge diffusion flames in hydrocarbon fuel jets." Proceedings of the Combustion Institute 30, no. 1 (January 2005): 375–82. http://dx.doi.org/10.1016/j.proci.2004.08.227.

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36

Kwack, E. Y., L. H. Back, and C. P. Bankston. "Electrostatic Dispersion of Diesel Fuel Jets at High Back Pressure." Journal of Engineering for Gas Turbines and Power 111, no. 3 (July 1, 1989): 578–86. http://dx.doi.org/10.1115/1.3240293.

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An experimental study of electrostatically atomized and dispersed fuel jets has been conducted in room temperature N2 gas for various back pressures to 41.8 atm. No. 2 diesel fuel was injected through an electrostatic spray triode designed for high-pressure operation. Charge density measurements were conducted at various combinations of injection velocities, electric potentials, and back pressures. The charge density of fuel drops increased up to 1.5 C/m3 with increasing electric potential until breakdown occurred. After breakdown the charge density was reduced by 40 to 60 percent and again increased but more slowly as electric potential increased. At higher flow rates, breakdown occurred at higher voltages. At higher back pressure, lower charge density was obtained and breakdown occurred at higher voltages. Visual observations showed that significant electrostatic dispersion was accomplished at high back pressures, and that the average drop size was about the same as the spray triode orifice diameter.

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37

SUGANUMA, Hiroyuki, Masanori SASAKI, and Masahiro SHIOJI. "311 Study on SI Combustion Characteristics of Gaseous Fuel Jets." Proceedings of Conference of Kansai Branch 2008.83 (2008): _3–16_. http://dx.doi.org/10.1299/jsmekansai.2008.83._3-16_.

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38

Hu, F. Q., T. L. Jackson, D. G. Lasseigne, and C. E. Grosch. "Induced Mach wave–flame interactions in laminar supersonic fuel jets." Physics of Fluids A: Fluid Dynamics 5, no. 2 (February 1993): 422–27. http://dx.doi.org/10.1063/1.858865.

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39

Baev, V. K., and A. N. Bazhaikin. "Stabilization of diffusion flames of impacting and opposing fuel jets." Combustion, Explosion, and Shock Waves 52, no. 5 (September 2016): 514–23. http://dx.doi.org/10.1134/s0010508216050026.

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40

Rogers, Thomas, Phred Petersen, Lucien Koopmans, Petros Lappas, and Alberto Boretti. "Structural characteristics of hydrogen and compressed natural gas fuel jets." International Journal of Hydrogen Energy 40, no. 3 (January 2015): 1584–97. http://dx.doi.org/10.1016/j.ijhydene.2014.10.140.

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41

White, T. R., and B. E. Milton. "Shock wave calibration of under-expanded natural gas fuel jets." Shock Waves 18, no. 5 (September 30, 2008): 353–64. http://dx.doi.org/10.1007/s00193-008-0158-6.

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42

Ouellette, P., and P. G. Hill. "Turbulent Transient Gas Injections." Journal of Fluids Engineering 122, no. 4 (July 13, 1999): 743–52. http://dx.doi.org/10.1115/1.1319845.

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Compressible transient turbulent gaseous jets are formed when natural gas is injected directly into a diesel engine. Multi-dimensional simulations are used to analyze the penetration, mixing, and combustion of such gaseous fuel jets. The capability of multi-dimensional numerical simulations, based on the k-ε turbulence model, to reproduce the experimentally verified penetration rate of free transient jets is evaluated. The model is found to reproduce the penetration rate dependencies on momentum, time, and density, but is more accurate when one of the k-ε coefficients is modified. The paper discusses other factors affecting the accuracy of the calculations, in particular, the mesh density and underexpanded injection conditions. Simulations are then used to determine the impact of chamber turbulence, injection duration, and wall contact on transient jet penetration. The model also shows that gaseous jets and evaporating diesel sprays with small droplet size mix at much the same rate when injected with equivalent momentum injection rate. [S0098-2202(00)02304-X]

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43

ANTUNES, Eduardo, Andre SILVA, and Jorge BARATA. "Modelling of transcritical and supercritical nitrogen jets." Combustion Engines 169, no. 2 (May 1, 2017): 125–32. http://dx.doi.org/10.19206/ce-2017-222.

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The present paper addresses the modelling of fuel injection at conditions of high pressure and temperature which occur in a variety of internal combustion engines such as liquid fuel rocket engines, gas turbines, and modern diesel engines. For this investigation a cryogenic nitrogen jet ranging from transcritical to supercritical conditions injected into a chamber at supercritical conditions was modelled. Previously a variable density approach, originally conceived for gaseous turbulent isothermal jets, imploying the Favre averaged Navier-Stokes equations together with a “k-ε” turbulence model, and using Amagats law for the determination of density was applied. This approach allows a good agreement with experiments mainly at supercritical injection conditions. However, some departure from experimental data was found at transcritical injection conditions. The present approach adds real fluid thermodynamics to the previous approach, and the effects of heat transfer. The results still show some disagreement at supercritical conditions mainly in the determination of the potential core length but significantly improve the prediction of the jet spreading angle at transcritical injection conditions.

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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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45

Liu, C. H., R. M. Perez-Ortiz, and J. H. Whitelaw. "Vaporizer Performance." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 206, no. 4 (July 1992): 265–73. http://dx.doi.org/10.1243/pime_proc_1992_206_126_02.

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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.

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46

Winters, Andrew C., and Jonathan E. Martin. "The Role of a Polar/Subtropical Jet Superposition in the May 2010 Nashville Flood." Weather and Forecasting 29, no. 4 (July 22, 2014): 954–74. http://dx.doi.org/10.1175/waf-d-13-00124.1.

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Abstract Contributions to the increased poleward moisture flux that characterized the second day of the 1–3 May Nashville, Tennessee, flood of 2010 are examined from the perspective of polar and subtropical jet superposition and its influence on the secondary ageostrophic circulation. Employing the Sawyer–Eliassen circulation equation, the analysis reveals that the poleward moisture flux attributed to the jet increased nearly 120% prior to the second day of the event in response to the superposed jet’s ageostrophic circulation, helping to further fuel the production of heavy rainfall. The full Sawyer–Eliassen circulation associated with the superposed jet is further partitioned into its geostrophic and diabatic components. The geostrophic forcing drove midtropospheric ascent that fueled the production of deep convection and the record rainfall. The diabatic component, through forcing lower-tropospheric ascent and vigorous lower-tropospheric poleward moisture flux, provided the link between the tropical moisture and the deep convective environment. Since superposed jets, by their nature, develop on the poleward edge of the tropical or subtropical air, it is suggested that such a mutually reinforcing interaction between these two component forcings of the secondary circulation may routinely characterize the involvement of superposed jet structures in high-impact weather events.

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47

Lim, K. B., B. H. Chao, P. B. Sunderland, and R. L. Axelbaum. "A theoretical study of spontaneous ignition of fuel jets in an oxidizing ambient with emphasis on hydrogen jets." Combustion Theory and Modelling 12, no. 6 (November 18, 2008): 1179–96. http://dx.doi.org/10.1080/13647830802315095.

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48

Neonufa, Godlief, Meiti Pratiwi, Tirto Prakoso, Ronny Purwadi, and Tatang Soerawidjaja. "Catalytic thermal decarboxylation of palm kernel oil basic soap into drop-in fuel." MATEC Web of Conferences 268 (2019): 06014. http://dx.doi.org/10.1051/matecconf/201926806014.

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Catalytic thermal decarboxylation of basic soaps derived from palm kernel oil to produce dropin fuel was investigated. The C12/14 and C12/16 methyl ester had been used as the model compounds of this study. The purpose of this study was to produce drop-in fuel, especially jets biofuel, by catalytic thermal decarboxylation of basic soaps from palm kernel oils. In this study, two types of Magnesium-Zinc metal combination were used for preparing the basic soaps, both directly have a role as a catalyst. The reaction was carried out at 370°C and atmospheric pressure for 3 hours in the semi-batch reactor. Approximately 41 and 43 weight% of the yield and selectivity of about 97 and 98% toward the jets biofuel had been obtained in both experiments, respectively. The results showed that decarboxylation of basic soaps of C12/14 and C12/16 methyl ester were converted into drop-in fuel, especially jets biofuel in the relatively good yield of conversion.

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49

Guryanov, Alexander I., O. A. Evdokimov, S. V. Veretennikov, and M. M. Guryanova. "EXPERIMENTAL INVESTIGATION OF PREMIXED AIR–FUEL MIXTURES AND OF THE COMBUSTION SPECIFICS OF DIFFUSION FUEL JETS." International Journal of Energy for a Clean Environment 18, no. 4 (2017): 335–48. http://dx.doi.org/10.1615/interjenercleanenv.2018021223.

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50

Bieder, Ulrich, and Alexander Rashkovan. "Baffle jetting: CFD analysis of plain jets impinging on fuel rods." Progress in Nuclear Energy 114 (July 2019): 31–45. http://dx.doi.org/10.1016/j.pnucene.2019.02.006.

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Journal articles on the topic 'Fuel jets'

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