Simultaneous Optical Measurement of Soot Volume Fraction and Temperature in Heptane Pool Fires.
Simultaneous Optical Measurement of Soot Volume Fraction
and Temperature in Heptane Pool Fires.
(305 K)
Choi, M. Y.; Hamins, A.; Rushmeier, H.; Hubbard, A.;
Kashiwagi, T.
Combustion Institute/Eastern States Section. Technical
Meeting, 1993 October 25-27, 1993, Princeton, NJ,
366-369 pp, 1993.
Keywords:
soot; optical measurement; volume fraction; temperature;
heptanes; pool fires; heat flux
Abstract:
In large pool fires radiative heat transfer governs the
burning and flame spread rates and therefore is a key
factor in assessing potential fire hazards. The
radiative heat feedback from the flame to the fuel
surface is controlled by the temperature and soot
distribution inside the fire. Early attempts at
modeling this process involved several assumptions
including the use of average flame emissivity, constant
flame temperatures, absorption/emission cofficients as a
function of height and effective flame shapes. Due to
the turbulent nature of these fires, the use of mean
radiative properties can lead to significant differences
between the predicted and measured fuel burning rates.
Markstein investigated spatial and temporal variations
of the emission intensity for pool fires and suggested
the importance of turbulent fluctuations of temperatures
and soot volume fractions on the heat transfer
mechanism. Direct integration of the turbulent
radiative heat transfer to the fuel surface requires the
time-varying local temperature and emissivity
distributions within the region between the fuel surface
and the flame. The primary motivation for this study is
to understand the mechanisms governing the gasification
and heat feedback rates to the fuel surface. The 3-line
emission/absorption technique was used to measure the
temperature and soot volume fractions in pool fires
burning heptane. The temporal and spatial results will
be used to determine the radiative feedback to the
surface and the burning rate using a reverse Monte Carlo
method for comparisons with the measured values.
