Experimental study on cellular instabilities in hydrocarbon/ hydrogen/carbon monoxideeair premixed flames Tran Manh Vu a,b , Jeong Park b, *, Jeong Soo Kim b , Oh Boong Kwon b , Jin Han Yun c , Sang In Keel c a Faculty of Civil Engineering, Ho Chi Minh City University of Technology, 268 Ly Thuong Kiet Street, District 10, Ho Chi Minh City, Viet Nam b School of Mechanical Engineering, Pukyong National University, San 100, Yongdang-dong, Nam-gu, Busan 608-739, Republic of Korea c Environment & Energy Research Division, Korea Institute of Machinery and Materials, 171 Jang-dong, Yuseong-gu, Daejeon 305-343, Republic of Korea article info Article history: Received 10 August 2010 Received in revised form 12 February 2011 Accepted 15 February 2011 Available online 16 March 2011 Keywords: Cell formation Diffusional-thermal instability Hydrocarbon Hydrodynamic instability Premixed flame abstract To investigate cell formation in methane (or propane)/hydrogen/carbon monoxideeair premixed flames, the outward propagation and development of surface cellular instabil- ities of centrally ignited spherical premixed flames were experimentally studied in a constant pressure combustion chamber at room temperature and elevated pressures. Additionally, unstretched laminar burning velocities and Markstein lengths of the mixtures were obtained by analyzing high-speed schlieren images. In this study, hydrodynamic and diffusional-thermal instabilities were evaluated to examine their effects on flame insta- bilities. The experimentally-measured unstretched laminar burning velocities were compared to numerical predictions using the PREMIX code with a H 2 /CO/C 1 eC 4 mecha- nism, USC Mech II, from Wang et al. [22]. The results indicate a significant increase in the unstretched laminar burning velocities with hydrogen enrichment and a decrease with the addition of hydrocarbons, whereas the opposite effects for Markstein lengths were observed. Furthermore, effective Lewis numbers of premixed flames with methane addi- tion decreased for all of the cases; meanwhile, effective Lewis numbers with propane addition increase for lean and stoichiometric conditions and increase for rich and stoi- chiometric cases for hydrogen-enriched flames. With the addition of propane, the propensity for cell formation significantly diminishes, whereas cellular instabilities for hydrogen-enriched flames are promoted. However, similar behavior of cellularity was obtained with the addition of methane, which indicates that methane is not a candidate for suppressing cell formation in methane/hydrogen/carbon monoxideeair premixed flames. Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction The significance of global climate change and the depletion of existing fossil fuels have led to the identification of replace- ment fuels. In this sense, hydrocarbons such as methane and propane are considered to be an attractive potential fuel in spark-ignition engines [1,2]. However, one of the problems is the release of carbon dioxide products if hydrocarbons are used as an alternative fuel. In recent years, hydrogen has been widely used due to its advantages such as a high burning * Corresponding author. Tel.: þ82 51 629 6140; fax: þ82 51 629 6126. E-mail address: jeongpark@pknu.ac.kr (J. Park). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 36 (2011) 6914 e6924 0360-3199/$ e see front matter Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2011.02.085