Explain the process of combustion in diesel engine.

Combustion in CI Engines :The combustion in CI engines is taking place in following stages as shown in figure 1. Ignition delay period: During this period, some fuel has been admitted but not yet ignited. The delay period is a sort of preparatory phase. It is counted from the start of injection to the point where P-ɵ curve separates from air compression curve. 2. Rapid or uncontrolled combustion : In this stage , the pressure rises rapid because during the delay period the fuel droplets have time to spray and have fresh air around them. This period is counted from end of delay period to the max pressure on indicator diagram. 3. Controlled combustion : uncontrolled combustion is followd by controlled combustion stage. The period of this stage assumed to be at the end of max cycle temperature. 4. After burning : It is expected to end combustion process after third stage. Because of poor distribution of fuel particles combustion still continues during remaining part of expansion stroke. This is after burning .