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Indexed by:Journal Papers

Date of Publication:2020-05-15

Journal:FUEL

Included Journals:EI、SCIE、SSCI

Volume:268

ISSN No.:0016-2361

Key Words:Diesel engine; Double-layer diverging combustion chamber; BSFC; Exhaust emissions; Combustion process

Abstract:Double-layer diverging combustion chamber (DLDC chamber) was designed for the diesel engine to increase the in-cylinder air utilization and change the fuel-air mixing process by diverging the fuel spray into two layers. A 135-type diesel engine was selected to find out the DLDC chamber performance characteristics and compare the DLDC chamber performance with the re-entrant chamber. The influence of the injection parameters on the DLDC chamber performance showed that the injection timing affected the chamber performance more significantly than the injection pressure; advancing the injection timing decreased the BSFC; postponing the injection timing showed the potential to decrease the exhaust emissions simultaneously and decreasing the injection pressure showed the potential to decrease the NOx without worsening the BSFC. The comparison results showed that the DLDC chamber had lower BSFC and provided less soot with specific injection timings, while the DLDC chamber obtained higher NOx; the DLDC chamber had a longer ignition delay with a higher maximum in-cylinder pressure and higher heat release rates during the premixed combustion phase. The investigation suggested that the injection parameters affected the fuel-air mixing and combustion in different layers and made the DLDC chamber obtain different engine performance; making more fuel spray flow into the upper layer and the top clearance reduced the BSFC of the DLDC chamber but sometimes increased the soot; diverging the fuel spray into the two layers improved the fuel-air mixing process and increased the heat release rates of the premixed combustion phase but still resulted in some inhomogeneous mixture distribution.