Thermal structure of flame front during downward flame spread was experimentally measured with the help of the coordinate transformation method for XPS foam with a thickness of 1.6 cm. Temperature and temperature gradient in the condensed phase, the shape of the molten liquid of XPS fuel, and heat flux through the solid, were obtained. The results show that temperature and temperature gradient gradually decrease from the surface to the inner XPS foam. The temperature distribution also illustrates the shape of the interface between melting liquid and solid. It shows that the interface between the solid and the liquid is flatter in the initial stage than that in the later stage, and the slopes of the solid-liquid interface are in the range about 30-50 degrees. The results also show that the melting layer is thinnest near the flame front and it is thicker for the location farther away from the flame front in the burning area. The molten liquid adheres to the back wall with the downward burning of the XPS sample, which increases the area of the burning surface at the top of the melting layer, and consequently, increases the flame height. In addition, the vertical heat conduction from the melting layer to the unburned zone is calculated by the integration of heat flux along the solid-liquid interface, and the result shows that the average heat flux through solid here is about 580 W/m2.

International Seminar on Fire and Explosion Hazards (9; 2019; Saint Petersburg, Russia). Proceedings of the Ninth International Seminar on Fire and Explosion Hazards [Электронный ресурс]: 21-26 April 2019, Saint Petersburg, Russia. Vol. 2 / Peter the Great St. Petersburg Polytechnic University, Autonomous Non-Profit Organization "Fire and Explosion Safety", Gefest Holding Ltd ; [edited by A. Snegirev [et al.]. — Электрон. текстовые дан. (1 файл : 98,7 Мб). — Saint Petersburg, 2019. — Загл. с титул. экрана. — Свободный доступ из сети Интернет (чтение, печать, копирование). — Adobe Acrobat Reader 7.0. — <URL:http://elib.spbstu.ru/dl/2/k19-97.pdf>. — <URL:http://doi.org/10.18720/SPBPU/2/k19-97>.