Research On The Influence Of EDI+GPI Ignition Engine Knocking

The automotive industry has completed a major shift toward downsized boosted direct injection engines,but the performance is further constrained by the detonation.Some researchers have advocated the addition of ethanol as an alternative fuel,which has higher octane number,faster flame propagation velocity and greater latent heat of vaporization than traditional gasoline.The currently used E10 or E85 can not maximize the utilization of ethanol in all operating conditions.In order to make full use of the advantages of ethanol fuel,combining the advantages of fuel injection with direct injection and port injection using EDI + GPI dual injection technology,the blend ratio of ethanol to gasoline can be adjusted online to improve engine compression ratio resulting in optimized engine performance.The goal of this paper is to investigate the physical properties of ethanol and the thermodynamic conditions that affect the detonation of EDI + GPI engines using experiment and numerical simulations.Firstly,the potential of improving the detonation performance of EDI + GPI engines by increasing the ratio of ethanol energy was experimentally studied.At the three test loads,EER between 22% and 26% was sufficient to keep the combustion phase at an optimum without knocking.Secondly,the spray characteristics of EDI + GPI dual injection were studied by numerical simulation,and the influence of the physical factors of ethanol on the detonation of EDI + GPI engine was further analyzed.The simulation results show that the swirling flow of intake air in the cylinder seriously affects the development of GPI and EDI spray process,which enhances the heat and mass transfer between fuel and gas.EER23 increased to EER80,and the average temperature in the GPI cylinder decreased by 5K to 20 K,and the cooling effect of ethanol was significant.EER0 increased to EER31.7,flame propagation speed increased,if the EER further increase,the combustion chamber ethanol cooling effect and the fuel evaporation worse,the wall effect is aggravated,the combustion effect worsened.Finally,the influence of thermodynamic conditions on the detonation of EDI + GPI engine was analyzed by numerical simulation.The simulation results show that the influence of temperature on the detonation is less than the pressure,which depends on the energy density.With the increase of EER,the increase of ignition advance angle needs to be controlled within the proper range to better optimize the combustion process.At EER31.7,ignition timing was significantly better than that of 30 CAD BTDC at 28 CAD BTDC combustion.