Prediction of Strati ed Charge Divided Chamber Engine Performance

Abstract

Abstract. Certain strati ed charge divided chamber engines have a very small pre-chamber, equipped with a spark plug and a main chamber connected to the pre-chamber through nozzles. A theoretical model is presented in this research to predict ignition delay and initiation of combustion in the pre-chamber. It considers ame progress in the pre-chamber up to the point where the ame penetrates the main chamber through the connecting nozzles. Step by step calculations then continue in the main chamber and the mass fraction burned and the energy release rate are calculated. The process continues to the point where all the fuel is burned. At each step, due to a one degree rotation of the crank shaft, there is a change in the cylinder volume, due to the movement of the piston and, also, a change in the mole fraction burned, due to the burning of a fraction of the mixture. Considering heat transfer from the cylinder contents to its surrounding area, some important operating parameters, such as indicated power, indicated thermal e ciency, indicated speci c fuel consumption, indicated mean e ective pressure and volumetric e ciency, are predicted. Stepwise calculations also provide in-cylinder pressure-volume and pressure-crank angle diagrams, as well as the in-cylinder contents temperature variation with the crank position and concentration of species existing in the combustion products. Predicted values obtained by the present model are compared with corresponding experimental values available in the literature to evaluate the accuracy of the model. The comparison shows reasonable agreement between theoretical and measured values.