Experiment of Gasoline Engine on Extending Diluted Combustion Limit with Swirl-Tumble Flow

The effects of pure tumble flow and swirl-tumble flow on combustion, diluted combustion limit, fuel economy and emissions were studied on a four-valve gasoline direct injection engine at part load under air dilution condition and exhaust gas dilution condition, respectively. The results show that under air dilution condition, compared to the original engine with a weak tumble flow and λ limit of 1.37, the high tumble flow can extend the λ limit to 1.44 and reduce the brake specific fuel consumption (BSFC)by 10%. The combination of swirl and tumble flow (swirl-tumble flow)can further extend the λ limit to 1.51 and reduce the BSFC by 12%. Under exhaust gas dilution condition, compared to the original engine with a weak tumble flow and EGR limit of 23%, the high tumble flow can extend the EGR limit to 27% and reduce the BSFC by 5%. The swirl-tumble flow can extend the EGR limit to more than 28% and reduce the BSFC by 8%. Compared to the original engine with weak tumble flow, the combination of high tumble flow and diluted combustion can reduce NOx and CO emissions by up to 69% and 89% respectively and increase the HC emissions by up to 74%. While the swirl-tumble flow and diluted combustion can reduce NOx and CO emissions by up to 63% and 87%, and increase the HC emissions by up to 44%. © 2021, Editorial Office of the Transaction of CSICE. All right reserved.