A thermal formulation for single-wall quenching of transient laminar flames

Couto

Volume 2: Simple and Combined Cycles; Advanced Energy Systems and Renewables (Wind, Solar and Geothermal); Energy Water Nexus;

2014

The present study addresses SYNGAS combustion in static chamber, using both experimental and numerical approaches, in order to derive the quenching distance and heat flux in laminar syngas-air flames. Three typical mixtures of H2, CO, CH4, CO2 and N2 are considered as representative of the syngas coming from wood gasification, and its laminar combustion will be performed in a static spherical vessel. A two dimensional CFD model is used and validated under experimental runs. The classical Woschni model based on the hypotheses of forced convection and the Rivère model based on kinetic theory of gases are included in the CFD approach. The paper considers two different approaches for chemical reactions: the use of eight reactions and the multizone model. Temperature and pressure analysis is also being carried out. The numerical results are in good agreement with experimental ones. This study could be very useful in predicting the physical conditions of the quenching distance where the measurement is not possible such as in engines and the possibility of using this model in internal combustion engines.

Section: Flame Propagationmentioning

confidence: 99%

Syngas Combustion Analysis Using an Experimental and Numerical Approach

Couto

Volume 2: Simple and Combined Cycles; Advanced Energy Systems and Renewables (Wind, Solar and Geothermal); Energy Water Nexus;

2014

“…The principle of LII is that soot particles absorb energy from a high-intensity sheet of pulsed laser light within a few nanoseconds, and then the heated particles glow with a blackbody-like incandescence that far exceeds their normal background level. Moreover, according to the blackbody radiation law, within a certain range of detection wavelengths, the radiation from the flame can be ignored before being heated [12]. In this LII technique, the second harmonic (532 nm, 20 mJ/pulse) was used to determine the soot formation and oxidation.…”

Section: Optical Setup and Methodologymentioning

confidence: 99%

“…Two different colors at 450 nm and 650 nm in the broadband of the soot emission spectrum were synchronously detected by the ICCD camera. The As in Reference [12], the flame position in the vicinity of the wall was recorded using a direct photography method. It was supposed that the natural luminous zone was associated with the appearance of excited radicals as a result of elementary reactions in the flame.…”

Section: Optical Setup and Methodologymentioning

confidence: 99%

“…Since more and more soot adherent to the wall surface grew over time, where normal flame structure could be destroyed, only the first 20 excellent images without damage were captured for analysis under any conditions and the signals were ensemble-averaged to reduce the effect of shot noise. As in Reference [12], the flame position in the vicinity of the wall was recorded using a direct photography method. It was supposed that the natural luminous zone was associated with the appearance of excited radicals as a result of elementary reactions in the flame.…”

Section: Optical Setup and Methodologymentioning

confidence: 99%

“…According to the relative position relation between flame propagation direction and wall surface, wall quenching can be divided into two types: head-on quenching (HOQ), where flame propagation is perpendicular to the wall, and side-wall quenching (SWQ), where the flame burns parallel to the wall [11]. Boust et al [12] ignited a quiescent methane-air mixture by spark electrodes in a constant-volume vessel. Quenching distance was measured through direct visualization and wall heat flux was processed from the time evolution of wall surface temperature, for both head-on and side-wall interactions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Wall Temperature on Acetylene Diffusion Flame–Wall Interaction Based on Optical Diagnostics and CFD Simulation

et al. 2018

Abstract:In order to elucidate the effect of wall temperature on a diffusion flame-wall interaction, an acetylene diffusion flame in a head-on quenching type was investigated. Direct photography, two-color thermometry, soot-LII (laser-induced incandescence), OH-LIF (laser-induced fluorescence) and numerical simulation with detailed reaction mechanisms were employed to find out the influence mechanism of wall temperature on near-wall combustion performance and emission characteristics. It is clearly shown through optical diagnostics and computation fluid dynamics (CFD) simulation that, compared with cold wall, the high temperature zone for hot wall becomes wider, and the smaller quenching layer is formed due to the higher wall heat flux. High-concentration soot emission is formed primarily near the outer flame far from the wall. CH 2 O, CO and HC emissions are decreased as wall temperature rises, while the formation of soot and A 4 is increased. A diffusion flame-wall interaction structure is proposed to reveal the influence mechanism of wall temperature.

Investigation on quenching characteristics of parallel narrow channels for deflagration flames

Guo

Wang

et al. 2023

Fire and Materials

A set of experimental equipment for quenching the deflagration flame in linked vessels with parallel narrow channels was proposed. The quenching effects of the deflagration flame in the linked vessels were investigated, the influence law and mechanism of parallel narrow channels on the deflagration flame was analyzed. The results showed that the Pmax and the (dP/dt)max at each position were both lower than without parallel narrow channels, which indicated that the propagation of flame was inhibited by parallel narrow channels effectively, and the explosion intensity was also reduced. The pressure oscillation phenomenon inside the linked vessels disappeared due to the inclusion of parallel narrow channels. The deflagration flame was successfully quenched when the channel gaps were 0.5, 1.5, and 3 mm, but failed to be quenched when the channel gap was 6 mm. The quenching distance and the average propagation velocity of the deflagration flame in parallel narrow channels increased with the increase of the channel gap. When the channel gap was 6 mm, the deflagration flame completely passed through parallel narrow channels, and the average propagation velocity of deflagration flame was significantly greater than that when the deflagration flame was successfully quenched.