Abstract
Recently, the environmental issues on an earth scale and the depletion of energy resources are requiring internal combustion engines to improve fuel economy and to reduce NOx emissions and particles urgently, which cause mainly atmospheric pollution. For this purpose, an alternative fuel and new combustion techniques have been studied so far. In this context, the interest in using alcohols as an engine fuel has increased. Among the various alcohols, Ethanol is known as the most suited fuel for spark-ignition engine. The most attractive features of Ethanol as an SI engine fuel are that Ethanol can be produced from renewable energy sources such as agricultural products and it has high octane number. Ethanol can be used in SI engines as pure or blending with gasoline. For pure Ethanol some modifications on engine design, where it can be used in SI engines by blending with gasoline at low concentrations without any modification. As the combustion properties of Ethanol, however, differ from those of gasoline fuel, it is necessary to investigate the combustion characteristics of Ethanol and the effects of Ethanol addition to gasoline in detail for the proper application of Ethanol to a new internal combustion engine. One of the most important properties of premixed flames is burning velocity. Laminar burning velocities play essential roles in determining several important aspects of the combustion process in spark ignition engines; among these are the ignition delay, the thickness of the wall quench layers, and the minimum ignition energy. It is found that a detailed knowledge of laminar premixed flames will provide insights into such properties as heat release rate, flammability limits, propagation rates, quenching and emissions characteristics. Flame chemistry is commonly studied by performing computer simulations of laminar one dimensional flame by solving complex chemical kinetic schemes. But the chemical kinetic data in such models are not always sufficiently well known for the predictions to be used with confidence. It is common to use measured burning velocities to validate these chemical kinetic schemes. The production of accurate measurements on laminar premixed flames therefore plays a key role in the process of understanding a large range of flames. Although the majority of fuel is probably burnt in turbulent combustion, data on laminar burning velocities are still needed as input to many turbulent combustion models. Also, in internal combustion engines the initial combustion is laminar, so again there is a need for the laminar burning velocity. The main purpose of this work is to measure the laminar burning velocity of Ethanol and clarify the effects of flame stretch on the laminar burning velocity.
Keywords: Ethanol flame, Burning velocity, Counter flow flame