In a combustion system, some elementary reactions act in two folds: inhibiting combustion by scavenging active radicals (H, O, and OH) and promoting combustion by releasing lots of heat. Sometimes, it is meaningful to distinguish the size of the inhibition and promotion effects. To decouple the thermal and chemical effects of a concerned elementary reaction, a numerical study was conducted based on selfmodified premix codes. The decoupling of the thermal and chemical effects on flame speed and temperature was achieved by using a self-modified function to calculate the generating rate of the targeted species in the considered elementary reaction and then deciding whether or not to include the contribution of target reaction when solving the component equations and the energy equations. This work takes the elementary reaction R812 (PO2 + H = HOPO) in combustion system of dimethyl methylphosphonate (DMMP) in methane/air premixed flame as the research object. Results show that, with 0.1% DMMP addition, contribution of thermal effect to flame temperature is generally greater than that of the chemical effect. However, the contribution of thermal effect to flame speed is consistently smaller than that of the chemical effect. If ignoring the heat release from R812, the flame temperature reduces quickly to below 1700 K which will lead to flame extinguishing. Sensitivity analysis on the laminar flame speed reveals that the inhibition efficiency of chemical effect is greater than the promotion efficiency of thermal effect of R812.

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. 1 / 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 : 118 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/k19-45.pdf>. — <URL:http://doi.org/10.18720/SPBPU/2/k19-45>.