Smoke and Fuel Consumption Measurements in a Direct Injection Diesel Engine with Variable Swirl

Results are presented from an experimental programme in which induction swirl ratio was varied from 0 to 5.1 in a 120.7 mm bore single cylinder naturally aspirated direct injection diesel engine. Trends in smoke and indicated specific fuel consumption with variable swirl at constant air-fuel ratio and start of combustion timing are presented for 4 engine speeds with two combustion chamber configurations and three fuel injection pump builds, each with the same injector nozzle. The results show clear optimum swirl levels for smoke and for ISFC, which are dependent on engine speed, piston cavity diameter and injection rate.