Research Article Finite Volume Simulation of High Speed Combustion of Premixed Air-Acetylene Mixtures in a Microchannel High speed combustion characteristics of premixed stoichiometric air-acetylene mixtures inside microchannels are numerically studied by solving a Navier-Stokes (NS) system of equations with a single-step chemistry model. A two dimensional explicit finite volume solver has been developed using modified advection upwind splitting methods (AUSM+) to predict the complex interactions among hydrodynamic processes, shock structures and combustion in microdimensions. The effects of channel aspect ratio and wall temperature on high speed micro- combustion have been studied in this work. The increase in wall temperature due to wall friction in reduced dimensions initiates the chemical reaction of the com- bustible mixture near the wall region, and the reacted zone reaches the centerline for smaller height-to-length ratios of the microchannels. The wall temperature plays an important role in hypersonic combustion at the microscale. Keywords: Combustion, Gases, Microchannels, Modeling Received: December 12, 2006; revised: December 27, 2006; accepted: January 11, 2007 DOI: 10.1002/ceat.200600389 1 Introduction Optimal designs of microelectromechanical systems (MEMS) and nanoelectromechanical systems (NEMS) are important ac- complishments of microengineering in recent years. Micro- electronics processing technology has become a potential field of research due to the development of various cost effective and efficient microdevices. Microcombustors, microburners, microactuators, etc., are the critical components of power MEMS devices. Due to the inherent complexity of the fluid dy- namics at the micrometer scale, experimental and numerical studies have been proposed for achieving a better understand- ing of the physics of microsystems. Many measurement tech- niques developed for macroscale combustion phenomena can- not be applied due to the miniaturization effect. Only limited work has been carried out on simulation of the reaction flow in microcombustors. Norton and Vlachos [1, 2] studied meth- ane-air and propane-air combustion characteristics and flame stability in microburners, reporting the vital role of wall ther- mal conductivity. Hua et al. [3, 4] studied the combustion characteristics of hydrogen-air mixtures in microcombustors, taking wall heat loss and heat conduction within the wall into account. Li et al. [5] predicted the flame temperature of pre- mixed flames involving hydrogen as the fuel. It is important to understanding the behavior of flame propagation and deflagra- tion to detonation transition (DDT) in microchannels for the design of micropropulsion devices, ultra-micro gas turbines and other micro power systems. Ott et al. [6] predicted the mechanism of laminar flame acceleration of the acetylene-air system in narrow channels. Gamezo and Oran [7] extended the work presented in [6] involving flame acceleration related to micropropulsion applications. Lee and Kwon [8] simulated flame propagation with heat loss to the wall in a closed vessel. Leach et al. [9] presented an analytical model for the effects of heat exchange within the structure of a micro-channel com- bustor, and heat loss from the structure to the environment. In this work, the high speed combustion characteristics of premixed stoichiometric air-acetylene mixtures inside micro- channels are numerically studied by solving a Navier-Stokes (NS) system of equations with a single step chemistry model. A two dimensional explicit finite volume solver has been devel- oped using modified advection upwind splitting methods (AUSM+) to predict the complex interactions among hydro- dynamic processes, shock structures and combustion in micro- dimensions. The nonreactive module of the developed code has been validated in previous works [10–12]. In this paper, the effects of the channel aspect ratio and wall temperature on high speed microcombustion have been investigated by the de- veloped solver. The rise in temperature near to the wall due to wall friction in microdimensions initiates the chemical reac- © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim http://www.cet-journal.com A. Chaudhuri 1 C. Guha 1 T. K. Dutta 1 1 Department of Chemical Engineering, Jadavpur University, Kolkata, India. – Correspondence: Mr.A.Chaudhuri(arnab_chaudhuri74@yahoo.co.in), Department of Chemical Engineering, Jadavpur University, Kolkata– 700032, India. Chem. Eng. Technol. 2007, 30, No. 5, 615–620 615