The calculation model of spray and combustion of a diesel engine was established by the AVL FIRE software. Based on the model

the influence of the key characteristics of combustion chamber on fuel economy and emissions was analyzed

and the optimization of combustion chamber was developed. The study shows that at full load and speed A

the optimized scheme improves the fuel air mixture

increases the air utilization rate and accelerates the post combustion speed. Thus improving the fuel economy and increasing the NOx emissions. At the 25% load of speed A

the optimized scheme reduces the air flow rate at the bottom of the combustion chamber bowl thereby reducing the wall heat transfer loss. This allows to have higher fuel economy with a reduction of NOx emissions. The engine experiment indicates that compared with original scheme

the fuel consumption of the optimized scheme is reduced by 2.0g/(kW·h) or so under full load operating conditions

the ESC 13 modes weighed fuel consumption is cut down by 2.2 g/(kW·h)

and the weighted NOxemissions are also equivalent.