The Simulation Of Oxygen-rich Or Nitrogen-rich Intake-air Control And Combustion In The Gasoline Engine

This paper research the control and combustion of the variable oxygen-enriched andnitrogen-rich intake air in the gasoline engine to improve combustion and emissions. Bychanging the oxygen and nitrogen components of the intake to reform the concentration anddistribution of the oxygen in chamber and cylinder, for rich oxygen in the zone near thecylinder wall can reduce the effect of cool-wall and flame-failure and rich nitrogen in thecenter of chamber can reduce the high temperature of there. By this way to reduce the CO,NOx and unburned particulate matter, and improve fuel economy finally.The experiments were simulated by CFD software Fluent. Study the law of oxygen-richand nitrogen-rich intake under different conditions and analysis its adaptability to differentshapes chamber of gasoline engine. For the characteristics of the distribution of oxygencomponent in the cylinder after intake, this study is mainly divided into two parts:oxygen-enriched intake and nitrogen-enriched intake. Start from the arrangement of eachnozzle (position and angle) and the adaptability to different shapes chamber. Then try tosearch a optimize control by changing the injection pressure, the injection concentration andspray pattern, etc.In the analysis of the oxygen-enriched intake, position I of the oxygen-enriched nozzlemore suitable to tub-shaped chamber, for its valve axis is parallel to the cylinder axis, whileposition II performance better for spherical and wedge-shaped chamber, for their valve axisand the cylinder axis are angled. In low-speed conditions, both the arrangement can formvariable density distribution of oxygen by center thick edge thin in cylinder at the end ofcompression process.In addition, at the simulation of the controllability of concentration field inhemispherical chamber cylinder with variable composition of nitrogen-enriched intake, thispaper find it is applicable to medium and low speed and more relative to the injectionpressure compare with injection concentration. The results show that1.2-1.8atm is anappropriate injection pressure at1000r/min, while1.8-2.4atm is better at3000r/min.And26%-28%is the appropriate injection concentration both to each other. But all theseInfluencing factors don’t work at high-speed.In the analysis of the nitrogen-rich intake under high speed conditions. The adaptive analysis of three different chamber found that, only the nozzle position I can form variabledensity distribution of oxygen by center thick edge thin in cylinder at the end of compressionprocess, but don’t adaptive to tub-shaped chamber. The controllability analysis ofnitrogen-rich intake in hemispherical combustion chamber found that it is applicable both tohigh and medium speed and more relative to the injection pressure too. And it is advised tochoose the low injection pressure of1.2-1.8atm, and low ejection concentration of80%-84%. At last the nitrogen-enriched intake for other shape chambers need further analysis,particularly for tub-shaped chamber.In addition, compare the combustion of different patterns oxygen-enriched intake andnormal intake found that, at low-speed, oxygen-rich intake improves the pressure andtemperature of cylinder but reduce the CO production. And at high and medium speed,compared to normal intake, the nitrogen-rich intake improve the combustion performance byreduce the temperature, pressure and CO in the cylinder.After all, the oxygen-rich and nitrogen-rich intake can achieve the variable densitydistribution control of concentration field in the engine, and improve combustionperformance. Especially, the analysis of the hemispherical chamber can provide for deeperanalysis to achieve the regional combustion balance in different shape of chamber, reducethe maximum combustion temperature and solve the problem of NOx emissions.