One-dimensional modeling approaches for the piloted ignition of poly (methyl methacrylate)

An unsteady one-dimensional solid-gas model is presented for the spontaneous and the piloted ignition of poly (methyl methacrylate) exposed to thermal irradiance. The mathematical description of the igniter (electrical spark) is given special attention. The simplest approach, namely the heating spark model, describes heat transfer from a pulsating high-temperature plane source (direct heating), together with the heat released by the pre-ignition reactions (indirect heating). A high overestimation of the thermal effects of the spark is observed owing to the one-dimensional approximation. An iterative solution method, indicated as the non-heating spark model, is also implemented to eliminate direct and indirect spark heating which, however, also cuts off possible flashing phenomena. The third approach, indicated as the chemical spark model, disregards the direct spark heating but still describes pre-ignition combustion. This approach is the simplest and the most effective for providing predictions in agreement with literature measurements for both the process dynamics and the ignition delay times.

Automated summary

This paper proposes a one-dimensional solid-gas model for the spontaneous and piloted ignition of poly(methyl methacrylate) under thermal irradiance. The mathematical description of the igniter (electrical spark) is given special attention. Three different approaches for describing the heating spark are presented, including direct heating, indirect heating, and pre-ignition combustion. An iterative solution method is also implemented to improve the accuracy of the predictions. The chemical spark model is found to be the simplest and most effective approach for providing predictions in agreement with literature measurements.