Effects Of Injection Direction And Injection Position On Combustion Characteristics Of Natural Gas Engine

Heavy energy consumption and serious environmental pollution forced people to speed up the pace of new energy development.As a kind of abundant and clean fuel,natural gas quickly becomes the main alternative energy in many industries,which has also promoted the rapid development of natural gas engines.The combustion characteristics of natural gas engine determine the power,economy and emission of the engine.It is very necessary to conduct in-depth research on it.This paper used 6K natural gas engine through CFD simulation technology to study the influence of different jet direction and jet position on the mixing and combustion characteristics of the engine with different nozzle and jet positions on the 6# cylinder with different pipe diameter at full load point.The study that the effect of jet direction on engine combustion characteristics under different nozzle diameters indicate that compared to the original nozzle,the gas nozzle with 6mm tube diameter is suitable for reducing the angle between the jet and the horizontal direction,which is beneficial to the formation of a more obvious concentration of mixed gas concentration in the upper concentration of the cylinder in the ignition time,so then it can increase the combustion rate in cylinder,the combustion intensity,the cylinder pressure and the heat release rate,and make the corresponding peak phase move forward.On the other hand,for a gas nozzle with a diameter of 8mm,increasing the angle between the jet direction and the horizontal direction is more conducive to the improvement of the combustion characteristics of the engine.The combustion characteristics of the engine were compared and analyzed at different intake locations,and the results of it show that: The change of intake position has an obvious influence on the intake uniformity of the engine.As the jet nozzle position extends to the inlet,the effect of the collision between the gas jet and the inlet and the inlet valve wall is enhanced.The mixing of CH4 and air is accelerated and the intake efficiency is improved,which makes it more obvious in the ignition timing cylinder of the engine.Though the study that the influence of jet direction and jet position on engine combustion characteristics,we can find that the difference of the diameter of the pipe mainly affects the jet velocity of gas.The difference of the velocity directly leads to the inhomogeneity of the change of the velocity field in the intake port,which leads to the difference in the stratification of the mixed gas under each working condition.Among them,the effect of the 6mm tube nozzle on the combustion results in different jet direction and jet position is obviously greater than that of the 8mm tube,and the corresponding optimization effect is more obvious.Therefore,the nozzle pipe diameter is appropriately reduced in the range of nozzle pipe diameter design,which is beneficial to the rapid injection of gas and the intake in the cylinder.The optimization effect is obvious.