A Numerical Investigation of the Effects of Creating an Air-Cell and Insulating the Piston on Combustion Process and Emission Formation in DI Diesel Engines

In the present article، the effects of air injection into the combustion chamber and utilization of an insulated piston have been investigated on combustion process، emission formation and performance characteristics in a direct injection diesel engine. In the proposed method، the secondary chamber is created inside the piston which is connected to the main combustion chamber via throats. The obtained results indicate that fabrication of the air-cell inside the piston could be very effective on reduction of the exhaust soot emission and has a slight effect on NOx reduction in a diesel engine. Utilizing an insulated piston causes a sizeable decrease in specific fuel consumption and increases mean effective pressure. Also، the results show that use of an insulated piston increases NOx due to causing high temperature inside the combustion chamber as a result of reducing the heat loss from the piston walls. The obtained results are compared with the corresponding results in the literature and show a good agreement.