Authors : C. Thayaparan , Monohar and S. Muthuraman
Abstract: In the diesel engine cylinder, the air fuel mixture is not at rest, but is in highly turbulent condition. The turbulence breaks the filament of a flame into a ragged front, thus presenting a far grater area of surface from which hear is being radiated; hence its advance is speeded up enormously. The combustion process may be developed in two stages. One the growth and development of a self-propagating nucleus flame and the other the spread of the flame throughout the combustion chamber. The former is a chemical process depending upon the nature of the fuel, temperature and pressure, the proportion of the exhaust gas and also upon the temperature coefficient of the fuel. During the combustion, there is a rise of temperature and pressure due to the combustion of the fuel ignited. Both temperature and pressure combine to accelerate the velocity of the flame front in compressing the unburnt portion of the charge in the knocking zone. Ultimately the temperature in this zone reaches such a high value feat chemical reaction proceed, at for grater rather than that at which the flame is advancing. Hence we have combustion accompanied by flame, producing a very high rate of pressure rise resulted in knocking. Knock characteristics of dual-fuel combustion in diesel engines using natural gas as primary fuel. This study investigates the combustion knock characteristics of diesel engines running on natural gas using pilot injection as means of initiating combustion. The diesel engines knock under normal operating conditions but the knock referred to in this paper is an objectionable one. In the dual-fuel combustion process we have the ignition stage followed by the combustion stage. These are three types of knock: diesel knock, spark knock and knock due to secondary ignition delay of the primary fuel (erratic knock). Several factors have been noted to feature in defiling knock characteristics of dual-fuel engines that include ignition delay, pilot quality, engine load and speed, turbulence and gas flow rate.
C. Thayaparan , Monohar and S. Muthuraman , 2007. Study of Combustion Phenomena in Diesel Engine for Proper Development of Power with Less Knocking. Journal of Engineering and Applied Sciences, 2: 435-439.