Visualization Researches On Ignition Processes Of Premixed Gas Ignited By Jets

The new energy vehicle is popular,but the traditional energy engine still has a wide range of irreplaceable field.In order to further optimize the combustion mode of internal combustion engine and improve the utilization rate of clean energy in internal combustion engine,the jet ignition processes of pre-chamber is studied in this paper under the thought of Jet Controlled Compression Ignition.It is hoped that the lean burn limit of the natural gas engine can be expanded by the application of the jet ignition system of pre-chamber,so that the thermal efficiency and exhaust emission of natural gas engine can be optimized.Based on the visualization experimental platform of constant volume vessel,the ignition and combustion processes of premixed gas is studied by schlieren method and direct photography.The main research content is as follows: the appearance of jet,the ignition time of premixed gas in the main chamber,the ignition position on the main chamber,the development of the early flame in the main chamber,the pressure in the ignition chamber,and the pressure and the pressure rise rate in the main chamber.In order to research the ingnition processes of premixed gas ignited by jets,the geometry parameters of pre-chamber and the fuel air equivalence ratio,pressure and temperature of premixed gas is studied in this paper.The conclusions are as follows: The increase of the diameter of the nozzle will make the ignition time advance and the ignition position away from the nozzle;When the nozzle diameter is large,the visible flame can be directly ejected;When the fuel has low concentration,increasing diameter of nozzle could improve the ignition ability,advanced ignition time,but the ignition area is concentrated,the flame development rate is slow and the peak pressure is low in the main chamber;When the nozzle diameter is adjusted,the ignition area is dispersed and the development rate of flame is large in the main chamber when there is no mass of open fire in the jet produce;When the ignition area is the main center of the main chamber,the flame development is the fastest and the peak pressure is the highest in the main chamber;The premixed gas in the main chamber can not be ignited when the nozzle diameter is too small;Increasing the volume of the pre-chamber will lead to the delay of the appearance time of jet produce,but more jet produce,wider range distribution,can provide greater ignition energy,make the flame burning faster,and reach a higher peak pressure in main chamber;Under the constant surface to volume ratio,by increasing the number of jetting holes in the ignition chamber,the adjustment of the ignition form and position can be realized,the igniton position can be wide range distribution and no no mass of open fire in the jet produce;The reduction of fuel air equivalence ratio results in the slow burning rate of the premixed gas in the ignition chamber,the ignition ability is weakened and the ignition time is delayed in the main chamber;When the fuel air equivalent ratio is increased in the pre-chamber,the ignition ability is enhanced,ignition time is advanced and lean burn limit is expanded;When the pressure of premixed gas is rised,the ignition ability of the pre-chamber is enhanced;But the ignition ability is weakened,ignition time is delayed because the concentration of the premixed gas is reduction as the temperature of premixed gas rises.