Study On Fuel Injection Strategy Of JCCI Engine With An Ignition-chamber

In order to improve the economy and to meet increa singly stringent emissions regulations,many kinds of new technology has been investigated,among which the diesel engine premixed compression combustion technology becomes a promising solution for its high efficiency and low emissions.Jet controlled compression ignition(JCCI)is a new way of premixed compression combustion technology.Its principle is that the diesel and air pre-mixture in main chamber is ignited by the hot jet issued from ignition chamber.In this way,the difficult problem of combustion phasing control of premixed compression ignition is solved.Ultra-low emissions can be achieved while maintaining good economy.The working process of JCCI with an ignition-chamber is complex,and ignition process is affected by many factors.After calculating and analyzing the working process,it’s found that the ignition process of natural gas and air mixture in the ignition chamber and the subsequent jet formation process are key factors influencing start.The diesel and air pre-mixture preparation is another important factor.Additionally,the temperature of intake air also has an effect on ignition process of the JCCI engine.In order to study ignition process and optimize fuel strategies of the JCCI engine,the engine was dragged by an electro-dynamometer at starting speed.Cylinder pressure and other data acquisition was done.Then AVL FIRE software was used for modeling and calculating the working process.The calibration and validation of the model was done by the motored experimental data.In this paper,the influence of fuel injection strategy on start reliability is analyzed including the gas injection parameters of the ignition chamber and the diesel injection parameters of the main combustion chamber.For the ignition chamber,the gas injection timing,injection quantity and injection pressure have effects on the residual gas cleaning and mixture igniting,and subsequent jet formation was analyzed,and optimized injection strategy of natural gas was proposed.For the main combustion chamber,the effect of diesel injection quantity and injection timing on the diesel air mixture formation is analyzed.Multiple injection strategy was introduced,and the injection timing and injection split was optimized.The start reliability of JCCI engine with an ignition chamber was improved successfully with all the measures taken.In order to further improve the start reliability of JCCI engine with an ignition chamber,the effect of temperature of intake air on ignition process is also analyzed.