- Author
-
Sauer, F. M.
- Title
- Ignition of Black Alpha-Cellulose Papers by Thermal Radiation: Square Wave Pulse.
- Coporate
- Department of Agriculture, Washington, DC
- Report
-
Interim Technical Report; AFSWP-869
September 1956
31 p.
- Keywords
-
paper
|
ignition
|
thermal radiation
|
exposure
|
time
|
thermal properties
|
thermal conductivity
|
irradiance
|
moisture content
- Abstract
- Available data on critical energies for sustained ignition of black alpha-cellulose paper in the absence of forced convective heat losses are correlated against exposure time on a nondimensional basis. Investigations cover a range of irradiance from 2 to 25 cal/cm2sec, exposure time from 0.1 to 4 seconds, and paper thickness from 2 to 30 mils. Ignition energies for papers of two nominal densities were determined. Results are presented in terms of an energy modulus, and the Fourier modulus, for a constant value. For Fourier moduli less than 0.4, the energy modulus approaches a constant value of approximately 0.11. As the Fourier modulus increases, the energy modulus decreases to a minimum value of 0.068 at a Fourier modulus of 0.8. For Fourier moduli above 0.8, the energy modulus increases with exposure time according to the equation. These results are valid for paper moisture contents of 4 to 5 percent, initial paper temperatures between 0 and 60C, and irradiance levels above the critical irradiance, estimated to be 2 cal/cm2sec. Presented correlations are within a maximum error of 95 percent. Regions of ignition, transient flaming, destruction (without flame), and nondestruction are illustrated in terms of the above-mentioned dimensionless moduli.