高强化柴油机喷雾射流对缸盖热负荷影响的研究

摘要

In view of the problem of too high thermal load in the bridge zone of cylinder head in highly intensified diesel engine, the effects of spray jet on the thermal load of cylinder head are studied.A scheme is proposed to control convective heat transfer from hot side and lower the thermal load of cylinder head by changing spray jet through the adjustments of angle between the axes of nozzle holes, the axial position of nozzle and spray cone angle.The results of 3D simulations on the in-cylinder combustion and heat transfer of a highly intensified diesel engine shows that, about 155°will be the best angle between the axes of nozzle holes, which is favorable for combustion but doesnt markedly increase the thermal load of cylinder head.Reducing the protruding distance of nozzle hole outlet will help improve combustion efficiency but may raise the thermal load of cylinder head concurrently.And the increase of spray cone angle will have adverse effect on thermal load of cylinder head.%针对高强化柴油机缸盖鼻梁区热负荷过高的问题,研究了喷雾射流对缸盖热负荷的影响,提出了通过调整喷孔夹角、喷孔位置和喷雾锥角来改变喷雾射流,从热侧控制燃气的对流传热,以降低缸盖热负荷的方法.对高强化柴油机进行缸内燃烧和传热过程等三维仿真的结果表明,高强化柴油机中,喷孔夹角约为155°时对燃烧最有利,且不会显著增加缸盖热负荷;减小喷孔出口突出距离有利于改善燃烧效率,但同时会提高缸盖的热负荷;喷雾锥角增大则不利于缸盖热负荷的改善.