涡流室式紊流燃烧柴油机中涡流室的流场特性

Flow field characteristics of turbulent combustion diesel engine with swirl chamber

通过FLUENT动网格技术模拟涡流室式紊流燃烧柴油机在活塞从下止点运动到曲轴转角为2°的喷油时刻缸内气体的流动特性,得出涡流室和气缸内气体的流场矢量图、湍流变化图、压强变化图和温度变化图。研究结果表明:活塞从下止点运动开始,气缸内空气被活塞压缩进入涡流室中,并在涡流室内部形成涡流;随着压缩的不断进行,涡流室内气流运动速度逐渐增加,并且流场逐渐由紊流变化成为涡流,室内压强和温度也逐渐升高,至曲轴转角为2°的喷油时刻,喷油孔附近空气流速约为24.1 m/s,压强约为2.3 MPa,温度约为845 K,在此状态下能较好地满足机内柴油的混合及燃烧需要。

For turbulent combustion diesel engine with swirl chamber, flow characteristics of gas in cylinder were simulated by the FLUENT dynamic mesh technology during the piston moving at bottom dead centre to 2° crank angle of fuel injection preceding. Vector diagram of flow field, pressure and temperature variation in swirl chamber and cylinder were obtained. The results show that when the piston moves at bottom dead centre, the air in cylinder is compressed into swirl chamber and eddy is formed. Along with the continuous compression, the gas flow kinematic velocity increases gradually in swirl chamber, and pressure and temperature increase too. When 2° crank angle of fuel injection precedes, gas flow velocity near oil nozzle hole is about 24.1 m/s, pressure is about 2.3 MPa and temperature is about 845 K, which can better meet the need of mixing and combustion in diesel engine.