Autoignition Dynamics of N-dodecane Droplets under Normal Gravity

• Published in: Combustion science and technology Vol. 194; no. 9; pp. 1830 - 1849
• Main Authors: Rose, Evan N., Nayagam, Vedha, Dietrich, Daniel L., Hicks, Michael C., Hegde, Uday G., Padilla, Rosa E., Williams, Forman A.
• Format: Journal Article
• Language: English
• Published: New York Taylor & Francis 04-07-2022; Taylor & Francis Ltd
• Subjects: autoignition; Dodecane; droplet combustion; Droplets; Flame propagation; Kernels; Spontaneous combustion; two-stage ignition
• ISSN: 0010-2202; 1563-521X
• DOI: 10.1080/00102202.2020.1840369

Experimental observations of two-stage autoignition dynamics of fiber-supported normal dodecane droplets in air under normal gravity are presented for a range of pressures and temperatures. High-speed shadowgraph imaging of the autoignition process reveals cool-flame and hot-flame front-formation and propagation dynamics. During two-stage ignition, a cool-flame kernel is first formed below the droplet; it then propagates toward the droplet along the fuel-vapor plume, and subsequently a hot-flame kernel is established behind the cool-flame front which rapidly expands, engulfing the droplet and establishing the classical diffusion flame. Results for the cool-flame and hot-flame kernel locations and their propagation speeds are presented for a range of ambient pressures, varying between normal atmospheric pressure and super-critical pressures and temperatures.