Transient burning rate of a noncharring plate under a forced flow boundary layer flame

SummaryExperiments were performed to investigate the flame thickness of the upward flame on the poly(methyl methacrylate) slabs with width of 100-400 mm. The results indicated that the flame thickness exhibited an increase first and then decrease trend in the upright orientation, and the maximum thickness location was approximately equal to the pyrolysis front location. The thickness of the flame along the lateral side of slab was less than that of the interior flame. The flame maximum thickness as a function of pyrolysis height and width was obtained, which showed the maximum thickness provided a power law increase with the pyrolysis height and width. Furthermore, the maximum thickness exhibited a power law increase with the total heat release rate as well. Based on the obtained flame thickness, the radiation heat flux at the pyrolysis height was The flame height correlation as shown in Equations 1 and 2 were obtained based on theoretical analysis and experimental data 4-9where a, b, and n are constants, x fl is the flame height, x p is the pyrolysis height, and _ Q ′ is the heat release rate (HRR) per unit width. However, the previous researches mentioned above did not consider the

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“…L is the characteristic length, taken as x p . And Δ T is the difference between the peak temperature and the molten surface temperature

{Nu}_{x} = 0.508 \Pr^{1 true/ 2} {(0.952 + Pr)}^{- 1 true/ 4} {Gr}_{x}^{1 true/ 4}

where Gr is the Grashof number, given as Gr = gα Δ tl 3 / ν 2 , and Pr is Prandtl number.…”

Section: Resultsmentioning

confidence: 99%

Experimental studies on the thickness of upward flame over poly(methyl methacrylate) slabs

et al. 2017

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“…The experimental set-up consists of a 15 cm square cross-sectional wind tunnel at the end of which we place a sample cable across the exit. A detailed description of the wind tunnel has been presented in earlier papers [13,15,16]. A schematic of the setup is shown in Figure 1.…”

Section: Methodsmentioning

confidence: 99%

Suppression and Extinguishment of Boundary Layer Flame over Communication Cable by `Gas-like' Water Mist in Cross-flow

Ndubizu

Ananth

Williams

2008

Journal of Fire Sciences

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Fire suppression experiments are performed with `gas-like' water mist in cross-flow on bare (without PVC jacket) communication cables to simulate a worst-case scenario. As fine water droplets are injected at low velocities, an initial envelope flame that engulfed the circumference of the cable recedes and forms a wake flame stabilized behind the cable. At high-mist concentration and/or high-air velocity, the flame is extinguished by shrinking rather than blowing-off, which is the case in flat plate boundary layer flames. The results show that ultra fine mist (UFM, Sauter mean droplet diameter, SMD = 3 μm) seems to be more effective in reducing the extinguishment time than high-pressure spray nozzle mist (SMD = 20 μm), which introduces spray-induced turbulence. The cable flame is extinguished rapidly after a threshold UFM concentration is exceeded. The threshold concentration decreases with increased air velocity. Finally, the copper cylindrical mesh, which is part of the cable, significantly enhances the effectiveness of UFM in flame extinguishment.

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“…The initial transient effects associated with flame spread are eliminated by obtaining the burning rate from the slope of the regression. Krishnamurthy and Williams [18], Ananth et al [19], and Ndubizu et al [20] measured average local regression rates in forced flows from thickness changes between the beginning and the end of the tests. These time-averaged regression rates differ from steadystate rates as they include transient effects.…”

Section: Introductionmentioning

confidence: 98%

Experimental observations on the steady-state burning rate of a vertically oriented PMMA slab

Pizzo

Consalvi

Querre

et al. 2008

Combustion and Flame

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Transient burning rate of a noncharring plate under a forced flow boundary layer flame

Cited by 24 publications

References 22 publications

Experimental studies on the thickness of upward flame over poly(methyl methacrylate) slabs

Experimental studies on the thickness of upward flame over poly(methyl methacrylate) slabs

Suppression and Extinguishment of Boundary Layer Flame over Communication Cable by `Gas-like' Water Mist in Cross-flow

Experimental observations on the steady-state burning rate of a vertically oriented PMMA slab

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