Fundamental laws governing subsonic and detonating gas combustion in inert porous media

Pinaev, A. V.; Lyamin, G. A.

doi:10.1007/bf00751555

Cited by 20 publications

(18 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This result is not surprising if one considers that for C2H2-O2 mixtures at atmospheric initial pressure, the detonation cell (Lyamin and Pinaev 1984;Pinaev and Lyamin 1989). The relative ranking of the velocity curves over ~, goes according to the detonation sensitivity of the different fuel-oxidizers.…”

Section: Velocity Measurementsmentioning

confidence: 63%

See 1 more Smart Citation

Influence of mixture sensitivity and pore size on detonation velocities in porous media

et al. 1995

View full text Add to dashboard Cite

Abstract. Experiments have been carried out to determine the dependence of the detonation velocity in porous media, on mixture sensitivity and pore size. A detonation is established at the top end of a vertical tube and allowed to propagate to the bottom section housing the porous bed, comprised of alumina spheres of equal diameter (1-32 mm). Several of the common detonable fuels were tested at atmospheric initial pressure. Resuits indicate the existence of a continuous range of velocities with change in ~, spanning the lean and the rich propagation limits. For all fuels in a given porous bed, the velocity decreases from a maximum value at the most sensitive mixture near q~ ~ 1 (minimum induction length), to V/Wcj ~ 0.3 at the limits. A decrease in pore size brings about a reduction in V/Vcj and a narrowing of the detonability range for each fuel. For porous media comprised of spherical particles, it was possible to correlate the velocity data corresponding to a variety of different mixtures and for a broad range of particle sizes, using the following empirical expression: V/Vcj = [1-0.35 log(dc/dp)] • 0.1. The critical tube diameter do is used as a measure of mixture sensititvity and dp denotes the pore diameter. An examination of the phenomenon at the composition limits, suggests that wave failure is controlled by a turbulent quenching mechanism.

show abstract

Section: Velocity Measurementsmentioning

confidence: 63%

“…Perhaps the most extensive study to date is the work by Lyamin and co-workers (Lyamin and Pinaev 1984;Pinaev and Lyamin 1989;Lyamin et al 1991). A variety of fuel-oxidizer mixtures were tested, predominantly in sand at different particle size ranges (.06-2.5 mm) and for a wide range of initial pressures (.01 to 5 MPa).…”

Section: Introductionmentioning

confidence: 99%

Influence of mixture sensitivity and pore size on detonation velocities in porous media

et al. 1995

View full text Add to dashboard Cite

show abstract

“…Pinaev & Lyamin [33] proposed that the high-velocity regime (they refer to it as the rapid compression regime) be characterized by a subsonic front velocity and a front peak pressure of greater than 1.1-1.2 times the initial pressure, corresponding to a front velocity of about 20 m s −1 . Lyamin & Pinaev [34,35] found that in very reactive mixtures, e.g.…”

Section: (C) Sound Velocity Regimementioning

confidence: 99%

“…Using a photomultiplier and piezoelectric pressure transducer, Pinaev & Lyamin [33] established that in this regime there is a smooth rise in pressure to a maximum that occurs at the start of the reaction zone, defined by the start of light emission. The pressure then falls to a final pressure below the initial pressure due to heat loss from the products to the porous medium and condensation of the water in the products.…”

Section: (C) Sound Velocity Regimementioning

confidence: 99%

“…The pressure then falls to a final pressure below the initial pressure due to heat loss from the products to the porous medium and condensation of the water in the products. Pinaev & Lyamin [33] showed analytically that the drop in pressure after the peak is due to the convective cooling of the combustion products. The peak overpressure was measured to be of the order of two to five times the initial pressure, which is substantially below the adiabatic constant volume explosion pressure for the mixture.…”

Section: (C) Sound Velocity Regimementioning

confidence: 99%

See 1 more Smart Citation

Explosion propagation in inert porous media

Ciccarelli

2012

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

Porous media are often used in flame arresters because of the high surface area to volume ratio that is required for flame quenching. However, if the flame is not quenched, the flow obstruction within the porous media can promote explosion escalation, which is a well-known phenomenon in obstacle-laden channels. There are many parallels between explosion propagation through porous media and obstacle-laden channels. In both cases, the obstructions play a duel role. On the one hand, the obstruction enhances explosion propagation through an early shear-driven turbulence production mechanism and then later by shock-flame interactions that occur from lead shock reflections. On the other hand, the presence of an obstruction can suppress explosion propagation through momentum and heat losses, which both impede the unburned gas flow and extract energy from the expanding combustion products. In obstacle-laden channels, there are well-defined propagation regimes that are easily distinguished by abrupt changes in velocity. In porous media, the propagation regimes are not as distinguishable. In porous media the entire flamefront is affected, and the effects of heat loss, turbulence and compressibility are smoothly blended over most of the propagation velocity range. At low subsonic propagation speeds, heat loss to the porous media dominates, whereas at higher supersonic speeds turbulence and compressibility are important. This blending of the important phenomena results in no clear transition in propagation mechanism that is characterized by an abrupt change in propagation velocity. This is especially true for propagation velocities above the speed of sound where many experiments performed with fuel-air mixtures show a smooth increase in the propagation velocity with mixture reactivity up to the theoretical detonation wave velocity.

show abstract

Porous Burners

Trimis¹,

Pickenäcker²,

Wawrzinek³

2005

Cellular Ceramics

View full text Add to dashboard Cite

Combustion processes dominate the entire energy and transport sectors. The different burner types mainly depend on the fuel type (gaseous, liquid, or solid) and the application requirements (operating conditions, size, and emission limits). Although all possible fuel types are presently being used, there are clear signs that natural gas is becoming of increasing importance, especially in fields where lowemission thermal energy is needed. This is the case in domestic appliances such as household heating and hot-water supply systems, where low cost is another important factor that burner must have to be of interest to the market. In industrial processes such as drying, coating, and preheating, more stringent emission requirements and increased process efficiency are the driving forces for further developments in burner technology.Two types of burner emissions are of major importance: 1) emissions due to incomplete combustion such as carbon monoxide and unburned hydrocarbons, and 2) hazardous combustion byproducts such as nitrogen oxides and sulfur oxides (greenhouse gases and/or toxic). Concerning emissions due to incomplete combustion, several measures can be applied, such as premixed combustion instead of diffusion-type flame, longer residence time in the reaction region, better insulation of the combustion chamber, higher combustion chamber temperature, more homogeneous mixing of the reactants, etc. Concerning combustion byproducts, the amount of sulfur oxides is related only to the sulfur content of the applied fuel (which is highest for solid fuels and lowest for natural gas), while the amount of nitrogen oxides, which are the most important nowadays in environmental protection, basically depends on the combustion temperature and the residence time at high temperatures. Thus, all efforts dealing with the abatement of nitrogen oxide emissions focus on reduction of the combustion temperature while taking into account that a spatially homogeneous minimum combustion temperature is compulsory to avoid incomplete combustion.Several concepts for low-NO x burners emerged in the last two decades, especially for burners fired with natural gas. A reduction in combustion temperature is common to all concepts, but it is realized in different ways: exhaust gas recirculation, internal recirculation regions, staged combustion with heat decoupling, and direct 5.5

show abstract

Fundamental laws governing subsonic and detonating gas combustion in inert porous media

Cited by 20 publications

References 12 publications

Influence of mixture sensitivity and pore size on detonation velocities in porous media

Influence of mixture sensitivity and pore size on detonation velocities in porous media

Explosion propagation in inert porous media

Porous Burners

Contact Info

Product

Resources

About