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Experimental Study on Effects of Sample Orientation on Non-Piloted Ignition of Thin PMMA Sheets.


pdf icon Experimental Study on Effects of Sample Orientation on Non-Piloted Ignition of Thin PMMA Sheets. (273 K)
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.

Keywords:

combustion; polymethyl methacrylate; ignition; solid materials; flame spread; ignition delay; lasers; buoyancy; flame ignition; flame behavior

Abstract:

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.