Showing papers on "Diffusion flame published in 2022"
TL;DR: In this paper , the formation of the underexpansion jet flame (UEJF) of premixed hydrogen/air in explosion venting was simulated by ANSYS Fluent, and the wave system structures of the UEJF were systematically analyzed.
50 citations
TL;DR: In this article , the chemical effects of NH3 on soot volume fraction (SVF) and polycyclic aromatic hydrocarbons (PAHs) spatial distributions and the soot morphological evolution were experimentally investigated in five C2H4 diffusion flames with and without NH3/Ar addition using nonintrusive and intrusive methods.
23 citations
TL;DR: In this paper , the authors investigated the interaction between thermodiffusive instabilities and turbulence in large-scale Direct Numerical Simulations (DNS) simulations of turbulent premixed lean hydrogen/air flames with a slot burner configuration at the same jet Reynolds number of Re=11,000 and Karlovitz number of Ka≈15.
21 citations
TL;DR: A review of the theoretical and experimental literature regarding the fundamental aspects of flames in nonvolatile solid fuel suspensions can be found in this paper , where a simple model based on matching the flame speed between thermally interacting fronts can capture the key physics.
19 citations
TL;DR: In this paper , the effects of NH3/H2/N2 addition on soot morphology and nanostructure in laminar co-flow diffusion flame of ethylene, by adopting the method of thermophoretic sampling combined with transmission electron microscope (TEM).
14 citations
13 citations
TL;DR: In this paper , numerical simulations were carried out to study the FA and DDT in a stoichiometric hydrogen-air mixture in narrow channels with width on the order of magnitude comparable to laminar flame thickness.
13 citations
TL;DR: In this paper , the thermal characteristics and flame behavior of dual tandem pool fires with equal and unequal heat release rates in varying separation distances were investigated under cross-flow conditions, where two square diffusion burners were used employing propane as fuel with varied HRR at six separation distances, with a total of 216 experimental conditions considered comprehensively.
13 citations
TL;DR: In this paper , the effects of adding different percentages of hydrogen and nitrogen to the fuel in a set of laminar coflow ethylene/air diffusion flames are investigated numerically by employing an in-house algorithm, the CoFlame code.
11 citations
TL;DR: In this paper, the effects of adding different percentages of hydrogen and nitrogen to the fuel in a set of laminar coflow ethylene/air diffusion flames are investigated numerically by employing an in-house algorithm, the CoFlame code.
11 citations
TL;DR: In this article , a series of turbulent premixed ammonia/hydrogen/air flames were investigated using the NH-PLIF diagnostics, and three correlations for the ST,GC were developed based on Damkohler's second hypothesis with consideration of the Le effect.
TL;DR: In this paper , visualization experiments are conducted in a constant volume combustion chamber using Mie-scattering and direct photography methods, and 3D simulation is used to supplement and explain the experimental phenomena.
TL;DR: In this paper, a numerical study was conducted to emulate the MILD combustion conditions in actual industrial furnaces and to explore the effects of different types of reactants dilution on NOx formation mechanisms and emission characteristics of methane and coke oven gas (COG) combustion.
TL;DR: In this article , the authors compared head-on quenching of statistically planar stoichiometric methane-air and hydrogen-air flames based on a Direct Numerical Simulation (DNS) database.
TL;DR: In this article , a series of experiments were carried out to investigate the effect of gaseous fire extinguishing agent on the hydrogen jet fire, and the flame behaviors under the effects of nitrogen and carbon dioxide jets were analyzed.
Abstract: Hydrogen has attracted much attention from governments and enterprises around the world due to its zero pollution and recycling use. However, it may bring safety problems such as hydrogen jet fire due to its wide flammability range and low ignition energy. Therefore, the methods of preventing hydrogen jet fire need to be explored urgently. In order to investigate the effect of gaseous fire extinguishing agent on the hydrogen jet fire, a series of experiments were carried out to study the flame behaviors under the effects of nitrogen and carbon dioxide jets. The fire extinguishing agents were released through a jet nozzle with diameter of 3 mm at the pressure of 11 atm. The flame length, thermal radiant flux and total heat flux were analyzed. The results show that the reduction ratio of vertical flame length increases with the decrease of the installation height of the extinguishing agent nozzle. It indicates that when the fire extinguishing agent is injected at the root of hydrogen jet flame, the fire may be extinguished. Due to the reduction of flame size, the thermal radiant flux received by the radiometer decreases, which corresponds to the reduction of flame radiation fraction. The total heat flux received in the downstream region of deflected flame is determined by the joint action of thermal radiation and convection. The convective heat transfer of high-temperature gas may cause the value measured by the heat flux meter on the flow path of the deflected flame to increase. Besides, the extinguishing limit for hydrogen jet flame under the effects of nitrogen and carbon dioxide jets are analyzed.
TL;DR: In this paper, the effect of high Karlovitz number (K a ) turbulence on density-weighted flame displacement speed, S d ˜, in a H 2 -air flame is investigated.
TL;DR: In this article, the effect of ethanol blending on engine particulate matter by comprehensively analyzing the soot process in the cylinder and exhaust particulate emissions was investigated in an optical direct injection spark ignition (DISI) engine.
Abstract: Ammonia (NH3) has emerged as an attractive carbonless fuel that can be co-fired with hydrocarbon fuel to reduce carbon dioxide emissions. To understand the influence of NH3 on soot formation when co-fired with hydrocarbons, the soot formation propensity is experimentally investigated via a laminar diffusion jet flame. A stable ethylene (C2H4) jet flame doped with NH3 at different volume percentages was established for the investigation of soot formation tendency. OH* chemiluminescence imaging revealed the change of flame structure, in which the signals emitted from the heat release region weakened with increasing NH3 addition, while the peak intensity shifted from the flame wings towards flame centerline region. The laser extinction method used to measure the soot volume fraction (SVF) at different heights above the burner, which showed the effect of NH3 on soot suppression is significant, owing to the interaction between N-containing compounds with carbon atoms that result in the reduction of key intermediate products required for the formation of benzene and polycyclic aromatic hydrocarbons (PAH). The effect of soot inhibition appears to be stronger for the low NH3 blend fraction. The chemistry effect of NH3 on soot reduction for C2H4 flame is ascertained by comparing with N2-doped C2H4 flame at the same volume percentage. This work highlights the need for improved understanding of hydrocarbon fuel with NH3 to enable detailed understanding on the soot generation and oxidation process.
TL;DR: In this article , a bluff-body stabilised turbulent jet flame burning in a stratified mode of combustion for fuel-lean methane/air mixtures is investigated by a flame-resolved simulation.
TL;DR: In this paper , the effect of high Karlovitz number ($Ka$) turbulence on density-weighted flame displacement speed in a H$_2$-air flame is investigated.
TL;DR: In this paper , an intricate investigation of enhanced oxidative reactivity and its dependence on the soot nanostructural properties induced by distinctive blending of a saturated and an unsaturated biodiesel surrogates with pure diesel was presented.
TL;DR: In this paper, an intricate investigation of enhanced oxidative reactivity and its dependence on the soot nanostructural properties induced by distinctive blending of a saturated and an unsaturated biodiesel surrogates with pure diesel was presented.
TL;DR: In this article , the effects of wall temperature and hydrogen addition on the flashback propensity of laminar premixed methane-hydrogen-air flames are investigated with OpenFOAM.
TL;DR: In this article , a meshed axisymmetric flame light field imaging was put forward, and the complicated distribution of temperature and radiative properties were considered in the model after validation using two absorption coefficients arranged at different region.
TL;DR: In this paper , the effect of ammonia (NH3) addition on soot growth and inception was investigated in laminar co-flow NH3-ethylene (C2H4) diffusion flames.
TL;DR: In this paper , the effects of CO2 and H2O diluents on soot formation in laminar diffusion flame were studied using a step-by-step decoupling method to separate the density, transport, thermal and chemical effects of the diluent by introducing four virtual substances.
Abstract: Oxygen-enriched combustion technology has an important application prospect, in which Oxy-steam combustion is a new generation of potential carbon capture technology. In this paper, the effects of O 2 /CO 2 and O 2 /H 2 O atmosphere on soot formation in laminar diffusion flame were studied. The flame image was taken by a color (CCD) camera in the visible band, the directional emission power in R and G bands was calibrated, and the two-dimensional distribution of temperature and soot volume fraction in the flame was reconstructed. The experimental results are compared with the numerical results, and the numerical results well predict the temperature of oxygen-enriched flame in O 2 /N 2 /CO 2 atmosphere, but overestimate the soot volume fraction. The laminar diffusion flame of ethylene in two kinds of oxygen-rich atmosphere was numerically studied by using a step-by-step decoupling method to separate the density, transport, thermal and chemical effects of the diluent by introducing four virtual substances. The calculation results show that combustion in O 2 /H 2 O and O 2 /CO 2 atmosphere reduces the flame peak temperature, but the effect on the flame centerline temperature distribution is different. The addition of H 2 O enhanced the concentration of OH through the reverse reaction rate of OH + H 2 =H + H 2 O, while the addition of CO 2 decreased the concentration of OH.O 2 /CO 2 combustion leads to the increase of flame height and radius, while in O 2 /H 2 O atmosphere, the flame height is shortened. Both CO 2 and H 2 O have a good inhibitory effect on soot formation. CO 2 in the oxidant affects soot nucleation and surface growth rate mainly by reducing flame temperature and H mole fraction, but not by promoting soot oxidation process. Water vapor also inhibits soot formation by increasing OH concentration through chemical effect. • The laminar diffusion flame of ethylene in oxygen-rich atmosphere was optically detected, and the temperature and soot volume fraction were reconstructed. • Using the ethylene laminar coaxial jet flame modeling method, the model can capture the various effects of CO2 and H2O on soot formation during ethylene combustion. • In the numerical calculation, the method of gradually decoupling the multiple effects of the diluent (CO2, H2O) is adopted. • The effects of CO2 and H2O diluents on soot formation were compared.
TL;DR: In this paper , an outwardly propagating spherical flame was employed to measure the flame speeds and Markstein lengths of C1C4 hydrocarbons, alongside precisely mixed blends of CH4/C2H6, CH4 /C3H8 and CH4 2/H2.
TL;DR: In this paper , the authors focus on flame structure analysis and composition space modeling of a multidimensional premixed hydrogen flame transitioning from a laminar stable condition to a thermodiffusively unstable state.
TL;DR: In this article , the authors compare roles played by leading and trailing edges of a premixed turbulent flame brush in its propagation and conclude that the leading edge plays an important role in the propagation of the brush.
TL;DR: In this article , the authors focused on the study of flame stabilization and local extinction of a spray flame in an atmospheric non-swirled test rig referred to as the CORIA Rouen Spray Burner.