Effect of Lip Jet Combustion Chamber on the Combustion and Emission Characteristics of a Diesel Engine
To enhance the fuel-air mixture quality within the combustion chamber of a high-pressure common-rail direct injection diesel engine,a lip jet structured combustion chamber was proposed.The fuel-air mixing character-istics within the lip jet combustion chamber were examined utilizing computational fluid dynamics(CFD)simulation,and the impacts of the combustion chamber structure and fuel injection parameters on combustion and emission characteristics were analyzed.The results show that the lip jet can effectively guide the fuel to be better distribution at the lip-mouth and lip-back areas of the combustion chamber,thereby forming an internal,middle,and outer triple-layer fuel-air mixture in the combustion chamber center,lip-mouth re-circulation zone and lip-back re-circulation zone.As a result,the quality of fuel-air mixture is enhanced.At speed of 2 000 r/min and full load conditions,when the spray angle α is 80°,the concave surface structure of the bottom of the re-circulation zone is conducive to spray diffusion.Under the condition of the nozzle diameter of 0.12 mm,the cone surface structure of the bottom of the re-circulation zone can create a clockwise vortex in the re-circulation zone,promoting the fuel-air mixing.Compared with the co combustion chamber,under the condition of the α of 80° and the nozzle diameter of 0.12mm,the lip jet combustion chamber with a cylindrical jet lip-back and a concave surface re-circulation zone bottom structure can achieve more uniform fuel-air mixture and more thorough combustion,reducing NOx and soot emissions by 11.0％and 32.4％,respectively.
万方数据
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