Experimental Study on Effects of Sample Orientation on Non-Piloted Ignition of Thin PMMA Sheets.
Experimental Study on Effects of Sample Orientation on
Non-Piloted Ignition of Thin PMMA Sheets.
Gotoda, H.; Manzello, S. L.; Kashiwagi, T.
Poster Session V and Reception;
Combustion Institute/Western States, Central States and
Eastern States. Fourth (4th) Joint Meeting of the U.S.
Sections. Hosted by The Eastern States Section of the
Combustion Institute and Drexel University. Poster
Session V and Reception. March 20-23, 2005,
Philadelphia, PA, 1-6 pp, 2005.
combustion; polymethyl methacrylate; ignition; solid
materials; flame spread; ignition delay; lasers;
buoyancy; flame ignition; flame behavior
Localized ignition of solid materials due to external
radiant energy and the subsequent transition to flame
spread are of importance to prevent fire hazards, and to
understand the complex coupling of chemical, thermal,
and fluid dynamics in solid combustion. Therefore,
several investigations relevant to ignition behavior
over solid materials (thermally thick PMMA) have been
conducted with or without external flow. In actual room
fires, the surface of solid materials is always
subjected to radiation from the fire in various
directions (e.g., ceiling, wall, and floor). Therefore,
it is important to investigate the influence of the
sample orientation angle on localized ignition behavior
and subsequent transition to flame spread over thin
solid materials. With respect to the influence of sample
orientation angle on ignition, it has been numerically
predicted that under conditions of low radiant flux, the
ignition delay time should significantly vary with a
change in the sample orientation angle. This study
examines the validity of the predicted results and also
extends current understanding of the ignition behavior
over a relatively thin PMMA sheet. The goal of the
present study is to characterize the variation in the
flame ignition delay time as a function of sample
orientation angle with different laser energy levels,
and to gain a better understanding on how buoyancy can
affect the flame ignition and the subsequent flame
behavior by changing the sample orientation angle.