Numerical studies on micro-combustion

Abstract

The evolution of the micro systems in the last years, created a need for new type of energy supply, with high-energy capacity, rapid recharge rate and long duration. At the moment, this type of systems rely only in battery power, but due to its limitations in terms of energy density and the number of recharge cycles, a new alternative has emerged, the development of combustion activated electric micro-generators. For this reason, in last decade many researchers dedicated their studies to better understand the micro-combustion phenomenon and subsequent design of high efficiency new micro systems.Another practical aspect of micro-combustion is the propulsion and electric supply of micro-satellites and micro-air vehicles for surveillance and reconnaissance.Recently, with the progress made in micro fabrication technology it was possible to develop microelectromechanical systems (MEMS), combining microelectronic with micro-mechanical in a single chip. This type of technology can be applied to different areas, however it still relies on an external power source, and for this reason it becomes also necessary to combine micro-power generators, eliminating the need for external power sources like batteries.The present project proposes a numerical study of the micro-combustion phenomenon, using OpenFoam (Open Field Operation and Manipulation). The objective is to analyse the models used to simulate the phenomenon, and develop new models to improve the predictions accuracy, essential in micro scale. It also pretends to study the geometry and the boundary conditions to increase the energy efficiency with low values of NOx, for homogeneous and heterogeneous reactions. The main objective of this study is to better understand the micro-combustion physics, analysing in detail the typical problems present in micro-combustion, namely: flame curvature or wall heat losses induced flame quenching, leading to flame extinction, Daou et al. (2001, 2002) and Ju et al. (2006); the flame-wall interactions creating a new weak flame regime, leading to high heat losses from the flame, Ju et al. (2002, 2005), Maruta et al. (2005, 2009) and Leach et al. (2005). In addition, it will be analysed the formation of the NOx.