The Effect of Dual-injector on Combustion Process of 396 Series Diesel Engine with Shallow Basin-shaped Combustion Chamber

Abstract

The 396 series diesel engine has high performance and reliability and long service life, and it has been widely used in many areas, especially in the field of military and industrial power plants. By applying shallow basin-shaped combustion chamber, the original fuel injection system of the 396 series diesel engine can be improved easily. With two symmetrical injectors in each cylinder, two injectors can be used to spray diesel at the same time, or one injector can be used to spray ignition diesel and the other injector can be used to spray biodiesel or alcohol fuel. A 3D combustion model of the 396 series diesel engine with shallow basin-shaped combustion chamber was established by using the computational fluid dynamics software FIRE. When 8-hole single-injector and 4-hole dual-injector were respectively adopted, the combustion process was simulated to compare and analyze the fuel spray, ignition start point, combustion pressure, combustion heat release rate, average temperature in cylinder and NO emission, and the impact of injection duration and fuel injection advance angle on the combustion process were discussed. By increasing fuel injection pressure, shortening fuel injection duration and increasing fuel injection advance angle properly, the combustion process of 396 series diesel engine can be improved when an 8-hole single-injector was adopted. When a dual-injector was applied, the fuel spray space distribution area was wide, combustion process was improved, cylinder pressure and temperature became high, combustion was relatively sufficient and thermal efficiency got high. Proper reduction of fuel injection advance angle and extension of injection duration can mitigate the condition of large NO emission and higher cylinder pressure when the dual-injector was adopted. The combustion process of the 396 series diesel engine with shallow basin-shaped combustion chamber can be improved obviously and the thermal efficiency can be improved by adopting the dual-injector and selecting proper injection duration and fuel injection advance angle. This research result is conductive to improve the combustion process of the 396 series diesel engine with shallow basin-shaped combustion chamber and provides a basis for using biodiesel and alcohol fuel in the diesel engine.