A methodology for estimation of local heat fluxes in steady laminar boundary layer diffusion flames

Singh, Ajay V.; Gollner, Michael J.

doi:10.1016/j.combustflame.2015.01.019

Cited by 94 publications

(64 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fit the non-dimensional temperature data at the fuel surface with an appropriate higher-order polynomial fit using a curve fit algorithm in Matlab or other dedicated software. 4 to 6 points near the surface were found to work well in previous studies [4][5][6] . 7.…”

Section: Discussionsupporting

confidence: 65%

“…The correlation of Collis and Williams was applied for heat losses from the sample [5][6]8 , (1) where Nu is the Nusselt number and Re = Ud w / v is the Reynolds number, which was obtained for 0.02 < Re < 44, with properties evaluated at the film temperature, Τ m , an average of the gas, Τ g, and thermocouple, Τ tc temperatures. Here, the Reynolds number Re is defined as indicated for the local gas flow velocity U and kinematic viscosity v. d w in Eq.…”

Section: Representative Resultsmentioning

confidence: 99%

“…Estimation of local temperature gradients using micro thermocouples is a particularly useful technique for the estimation of local mass burning rates and heat fluxes in these flames [4][5][6] . An analysis of literature data shows the difficulty of determining local heat transfer, combustion and friction coefficients at the condensed fuel surface, which are important for understanding the physics and the underlying mechanisms that drive a particular fire and its spread 6.…”

Section: Introductionmentioning

confidence: 99%

“…Set the temperature mapping interval based on the steady burning time interval of liquid and solid fuels. A recommended step size near the surface is 0.25 mm [4][5][6] . 14.…”

Section: Introductionmentioning

confidence: 99%

“…Using a data acquisition program on a computer, acquire data and write it to a measurement file. Note, sampling rates of 100 [4][5] to 500 6 Hz were used in past experiments. 18.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Singh

Gollner

2016

JoVE

Self Cite

View full text Add to dashboard Cite

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a microthermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided.

show abstract

Section: Discussionsupporting

confidence: 65%

Section: Representative Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Set the temperature mapping interval based on the steady burning time interval of liquid and solid fuels. A recommended step size near the surface is 0.25 mm [4][5][6] . 14.…”

Section: Introductionmentioning

confidence: 99%

“…Using a data acquisition program on a computer, acquire data and write it to a measurement file. Note, sampling rates of 100 [4][5] to 500 6 Hz were used in past experiments. 18.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Singh

Gollner

2016

JoVE

Self Cite

View full text Add to dashboard Cite

show abstract

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

et al. 2017

View full text Add to dashboard Cite

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

show abstract

Concurrent flame spread over vertically oriented paper sheet: The effect of sample thickness

2021

View full text Add to dashboard Cite

Summary Packing or printing paper made out of cellulose is widely produced and used in daily life. The thickness of thin material affects the burning process significantly. Concurrent flame spread is an effective approach when analyzing and evaluating the fire hazard for combustible materials. Conducting this work will provide further understanding of the flame spread mechanism and reduce fire hazard. It will also enable investigation of the effect of sample thickness on concurrent flame spreading over the thin paper sheets experimentally. Numerically examining concurrent flame spread over thin paper sheet with varied thicknesses is also performed using Direct Numerical Simulation, which can provide more details on flame spread process. Qualitatively, the model predictions agree reasonably with the experiment in terms of the flame contour, burn duration, and flame spread rate. The moving rates of the flame base and pyrolysis front decrease with sample thickness both experimentally and numerically. The relationship between net heat flux, flame standoff distance, and solid burning rate is analyzed, with the burning rate exhibiting a similar trend to that of the net heat flux. A correlation of the flame net heat flux with the normalized distance in the pyrolysis region is also established where the flame heat flux displays a decay trend with the normalized space.

show abstract

A methodology for estimation of local heat fluxes in steady laminar boundary layer diffusion flames

Cited by 94 publications

References 40 publications

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

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

Concurrent flame spread over vertically oriented paper sheet: The effect of sample thickness

Contact Info

Product

Resources

About