Huang Yongcheng£¬Zhou Longbao
(School of Energy and Power Engineering,Xi'an Jiaotong University,Xi'an 710049,China)
Abstract:Numerical simulations of direct injection diesel engine combustion at different engine operating conditions were conducted using the Kiva-3 code.The spray and combustion models of the code were modified.In the modification,Kelvinª²Helmholtz and Rayleigh-Taylor model was applied to describe the breakup process of injection spray and the improved Shell auto-ignition model was adopted to simulate the ignition process.In addition,the post-ignition combustion simulation was performed with a multiple laminar and turbulent characteristic timescale combustion model for taking into account the effects of both turbulence and chemical kinetic on combustion.The predicted values were compared with the engine testing data.The results calculated show good agreement with experimental results in cylinder pressure,in ignition delay period,and in heat release.The ignition site is located at the lower reaches of spray where the equivalent ratio of air-fuel mixture is slightly less than one.The modified Kiva-3 code could successfully predict the essential features of spray ignition and combustion processes.This work laid the foundation for optimizing the system parameters of direct injection diesel engines using multidimensional numerical simulations£®
Keywords£ºcharacteristic time combustion model;numerical simulation;direct injection diesel engine