Research On The Influence Of Dual In-cylinder Injector On Combustion Performance Of High-power Diesel Engine

The characteristic of high-power diesel engines is to improve fuel combustion heat release efficiency through high-boosting technology and high-pressure common rail electronic injection technology.However,the current diesel fuel injection system is difficult to meet the requirements of high-power diesel engines.The use of dual injectors in the cylinder can achieve the required fuel injection volume in a short time,and improve the air utilization rate by controlling the fuel injection direction of the dual injectors.This paper uses a high-power single-cylinder diesel engine as a research platform,mainly through the use of a dual injector system in the cylinder,keeping the center injector position unchanged,and setting a side injector on the right side to achieve a short time After reaching the required fuel injection volume after the liter power is increased,it is studied whether the diesel engine using the in-cylinder dual injection system can reach the corresponding level.This paper combines GT-Power and AVL-Fire software to carry out the simulation calculation of diesel engine,and studies the influence of side injector position,side injector injection parameters,and dual injector fuel ratio on the combustion process of high-power diesel engine.The main research contents are as follows:(1)Use GT-Power software to build a one-dimensional diesel engine model,combine the calculation results of the one-dimensional model to build a diesel engine three-dimensional simulation model in AVL-Fire software and verify the accuracy of the model.Simulate the effect of different relative positions of dual injectors on the combustion process.The research results show that the change of the relative distance mainly affects the degree of interference between the sprays of the two injectors and the quality of the oil and gas mixture.Under the premise that the position of the side injector is close to the center injector,the closer the position of the side injector is to the center of the combustion chamber,the better the combustion characteristics of the diesel engine,and the most accumulated heat in the cylinder.The relative included angle and the side-mounted injector nozzle hole wrap angle are coupled to the diesel engine combustion.When the relative distance is 2mm,there is the most suitable relative included angle to match the nozzle hole wrap angle.(2)Study the effects of injection parameters of side injectors,including the number of injection holes,injection hole diameter,injection duration,and injection timing on the combustion process of diesel engines.The research results show that the diameter of the side injector is reduced and the number of nozzles is increased,which obviously makes the fuel atomization more fully and increases the power performance in the early stage of combustion.However,the number of nozzles and the too small diameter make more fuel adhere to the wall.Affect the fuel utilization and combustion process,and reduce the cumulative heat release.The pressure,temperature,and heat release rate are significantly different when the injection duration and injection timing of the side injectors are changed.If the fuel injection duration is too long,the power will decrease,and if the fuel injection duration is too short,the fuel utilization rate and accumulated heat will decrease.When the fuel injection timing is before the center injector,the combustion efficiency is low.When the fuel is injected after the center injector,the overall effect is best when the fuel injection timing is 9°CA BTDC.(3)The overall fuel volume of the side injector is relatively small.The combustion process of a diesel engine under different fuel ratios of dual injectors is simulated.The research results show that reducing the fuel injection ratio of the side injector can effectively improve the diesel engine.Power,the cumulative heat release increased significantly.When the fuel injection ratio of the side injector is 5%,the cumulative heat release is 0.8% higher than when the fuel injection ratio is 10%,which is 2.8% higher than the fuel injection ratio of15%,and the relative power is 110 k W/L.Corresponding to the cumulative heat release increased by 0.1%.(4)According to the principle of equal efficiency,the cumulative heat release under the optimal scheme is compared with the cumulative heat release corresponding to the calculated liter power of 110 k W/L.The results show that by determining the relative optimal position of the side injector and the optimal injection parameters Under the premise,with proper fuel injection ratio,a small amount of fuel from the side-mounted injector can reach the corresponding level after the power is increased.