Prediction of Strati ed Charge Divided Chamber Engine Performance


Department of Mechanical Engineering,Sharif University of Technology


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
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 eciency, indicated speci c fuel consumption, indicated mean e ective pressure and
volumetric eciency, 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