车用汽油机外特性下排气能量流研究

基于发动机一维性能仿真计算方法,对某型汽油机排气能量流分布规律进行了研究,得出外特性下排气能量随曲轴转角的变化规律及分布特性;结合排气流速、压力和温度的研究,分别得到排气余动能、余压能和余热能的脉动特性.结果表明:在高速高负荷时废气能量回收潜力大,排气能量在低转速时比高转速时波动性要大;余热能在各排气能量中所占比例最大,其次是余压能,余动能最小;排气能量随发动机转速的增大而增大,但排气余动能和余压能增长幅度较小.本研究为进一步提高排气有效能回收潜力与回收方式的选择提供了数据支持.

Research on vehicle gasoline engine exhaust gas energy flow

The energy flow distribution of a gasoline engine is presented in this paper,on the basis of the method of onedimensional gas dynamics simulation. Then,the regularity between exhaust gas energy and engine crank angle was obtained under the external characteristics. The dynamic nature of exhaust gas energy flow was also analyzed based on exhaust gas velocity,exhaust pres sure as well as temperature fluctuations. The results show that exhaust gas energy has a greater recovery potential at high speed and high load operational conditions. Exhaust energy has higher volatility at low speed than that at high speed. The major exhaust gas energy is thermal energy, followed by pressure energy,and the kinetic energy is the minimun. Exhaust energy increaes with the engine speed, but the kinetic energy and pressure energy remain little changed. These re search results provide the data for further improving the exhaust energy recovery potential and re cycling method choice.