Applications of Turbulent and Multiphase Combustion

Kuo, Kenneth K.; Acharya, Ragini

doi:10.1002/9781118127575

Cited by 61 publications

(31 citation statements)

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“…A diffusion 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 flame was dominant at low pressures in the HMX/HTPB (hydroxyl-terminated polybutadiene) propellant studied which gives rise to burning rate exponent close to 0.5. At higher pressures, the monopropellant flame moves closer to the surface so that it becomes increasingly more important and the burning rate exponent approaches unity as predicted theoretically [5] similar to the data reported by Atwood et al [9]. The shift in pressure dependence was also a result of the melt layer interaction predominately for the coarser particles.…”

Section: Introductionsupporting

confidence: 87%

“…The difference in pressure dependence is indicative of changes in the combustion mechanism. Exponents near one indicate that combustion is dominated by a monopropellant flame [5,10,12]. The monopropellant flame standoff distance is likely shorter than any diffusion distance.…”

Section: Full Papermentioning

confidence: 99%

“…No experimental evidence has been reported that definitively shows a melt layer for CL-20 [4]. Investigations of the gas-phase flame structure in RDX and HMX have shown a dark zone present due to the slow chemistry of nitrogen oxide reduction following the initial N-NO 2 scission reaction [5,6,7]. However, no evidence of a dark zone for CL-20 was reported by Paletsky et al [8].…”

Section: Introductionmentioning

confidence: 99%

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Influence of Particle Size on the Combustion of CL‐20/HTPB Propellants

Kalman¹,

Essel²

2017

Propellants Explo Pyrotec

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The effect of nitramine particle size on the combustion behavior of inert binder based propellants has been extensively studied for RDX and HMX, but not CL-20. Although materials such as RDX and HMX are useful for particular combustion applications, CL-20 has a greater potential to improve the oxygen balance and energy density of a propellant. The current work investigates the effect of CL-20 particle size on the combustion of CL-20/HTPB propellants down to submicrometer sizes. An influence of particle size on the burning rate and combustion mechanism is reported. The 30 micrometer formulation burning rate data showed evidence of convective burning specifically at higher pressures, but the pressure dependence was comparable to neat CL-20 at pressures below 8 MPa. A change in the combustion mechanism of the submicrometer formulation as a function of pressure was determined to be a result of the interaction of the propellant flame and the combustion residue. Data suggested that at low pressures diffusion in terms of active cooling was dominant for the submicrometer formulation. Higher pressure data for both the submicrometer and 3 micrometer formulations suggest the degree of active cooling is decreased as the burning rate pressure exponent is near 0.5 for both propellants. The indirect evidence for the presence of a melt layer for CL-20 propellants is discussed.

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Section: Introductionsupporting

confidence: 87%

Section: Full Papermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of Particle Size on the Combustion of CL‐20/HTPB Propellants

Kalman¹,

Essel²

2017

Propellants Explo Pyrotec

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“…However, the oxidation of silicon takes place heterogeneously , and the heat release occurs at the solid surface. Further, while PS has poor thermal transport properties compared to bulk crystalline silicon, the thermal diffusivity of PS is higher (0.02-0.09 cm 2 /s) (Shen and Toyoda, 2002) than that of nanothermite formulations (0.001-0.005 cm 2 /s) (Pantoya et al, 2009) or typical composite propellants (∼ 10 −4 -10 −3 cm 2 /s) (Kuo and Acharya, 2012). Since the reactive wave propagation speed scales with the thermal diffusivity for a purely conductive propagation, and the heat release in PS occurs directly at the solid surface, PS can be expected to have a higher purely conductive component of the reactive wave propagation speed than most EM/nEMs.…”

Section: Downloaded By [University Of Western Ontario] At 00:05 09 Fementioning

confidence: 98%

Reactive Wave Propagation Mechanisms in Energetic Porous Silicon Composites

Parimi

Tadigadapa

Yetter

2014

Combustion Science and Technology

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Propagating reactive waves through porous silicon (PS)-sodium perchlorate composites and the generation of shock waves in the gaseous medium above the PS surface were studied using high-speed shadowgraphy. Propagation speeds were varied by changing the PS specific surface area (SSA) and the dopant type and level, and by the addition of organized microstructures along the wave propagation direction. Shadowgraph analysis showed that upstream permeation of hot gaseous combustion products was responsible for a two order of magnitude enhancement in the reactive wave propagation speeds obtained by the presence of organized microscale patterns on PS samples with low SSA (∼ 300 m 2 /g), which nominally exhibit baseline speeds of ∼ 1 m/s. Shadowgraph analysis and sound speed measurements on PS samples with high SSA (∼ 700 m 2 /g), which exhibit fast reactive wave propagations of ∼ 1000 m/s, indicated that neither the strong shock over the PS surface nor detonation of the porous layer were the mechanisms by which the wave propagated. Thermal analysis of PS showed that the heat release from exothermic reactions between PS and the oxidizer within the pores shifted to lower temperatures as the SSA of PS increased, which was accompanied by a reduction in the activation energy associated with the lowest temperature exothermic reaction between PS and the oxidizer. The combined experiments indicated that a combination of conductive and convective burning, possibly assisted by fast crack propagation within the silicon/porous silicon substrate, was responsible for the observed difference in propagation speeds and was the mechanism by which the reactive wave propagated with speeds on the order of a km/s within the porous layers.

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“…[3][4][5][6][7] Many important results have been obtained in these directions which are still subjects of ongoing intensive experimental and theoretical studies. [8][9][10][11][12][13][14][15] Yet, the large amount of energy released by a burning metal has undesirable consequences and represents a source of significant fire hazards, especially when metals are used in high-temperature and/or high-pressure oxidizing environments such as those prevailing in nuclear plants and oxygen supply systems. 16,17 The research conducted in metal-fire prevention has mostly consisted of carrying out standard tests that quantify the relative flammability of different metals, that is, their relative propensity to sustain combustion of metallic materials of standardized dimensions in oxygen atmospheres.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical study of iron and mild steel combustion in oxygen flows

2017

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The effects of oxygen flow speed and pressure on the iron and mild steel combustion are investigated experimentally and theoretically. The studied specimens are vertical cylindrical rods subjected to an axial oxygen flow and ignited at the upper end by laser irradiation. Three main stages of the combustion process have been identified experimentally: (1) induction period, during which the rod is heated until an intensive metal oxidation begins at its upper end; (2) static combustion, during which a laminar liquid "cap" slowly grows on the upper rod end, and, after the liquid cap detachment from the sample; (3) dynamic combustion, which is characterized by a rapid metal consumption and turbulent liquid motions. An analytical description of these stages is given. In particular, a model of the dynamic combustion is constructed based on the turbulent oxygen transport through the liquid metal-oxide flow. This model yields a simple expression for the fraction of metal burned in the process and allows one to calculate the normal propagation speed of the solid metal-liquid interface as a function of the oxygen flow speed and pressure. A comparison of the theory with the experimental results is made, and its potential application is mentioned.

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Applications of Turbulent and Multiphase Combustion

Cited by 61 publications

References 0 publications

Influence of Particle Size on the Combustion of CL‐20/HTPB Propellants

Influence of Particle Size on the Combustion of CL‐20/HTPB Propellants

Reactive Wave Propagation Mechanisms in Energetic Porous Silicon Composites

Experimental and theoretical study of iron and mild steel combustion in oxygen flows

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