This thesis describes experimental and theoretical work carried out during an investigation into heat release and heat transfer in Diesel engines. Experimental work included steady state measurements of the engine heat balance and local metal temperatures of cylinder liner, cylinder head and pistons. Transient measurements were made of cylinder pressure, fuel line pressure and needle lift. These diagrams were analysed to obtain experimental heat release and fuel injection rate. Theoretical calculations include some equations relating flow through poppet valves to swril generation in the open period, and more detailed treatment of the closed period processes. Two models for the closed period are developed, a relatively simple single zone model in which homogeneous conditions in' the cylinder are assumed, and a two zone model in which conditions are calculated separately for unburnt fuel and air, and combustion products. Relatively high gas temperatures are calculated in the combustion product zone, so gas composition is obtained as a mixture of 12 species using equilibrium calculations. The rate of mixing between fuel and air which controls the rate of combustion is calculated using empirical equations relating the mixing rate to the air swirl velocity and the concentration of combustion products in the mixing region. The theoretical model is at present in an early stage of development. Likely approaches for further theoretical development and experimental confirmation are discussed.
|Date of Award||1974|