内燃机燃烧放热率的典型特征参数对比以及对热-功转换效率的影响

基于汽油机多种工况的燃烧放热规律与指示热效率的实测结果,对评价内燃机热功转换过程相位的4种典型燃烧特征参数进行了分析与对比,指出了某些特征参数在结论方面的偏颇之处,并对原因进行了分析.研究表明,从指示热效率的角度来看,放热规律曲线面心值位置并不是越靠近上止点越好,有效膨胀比值也不是越大越好;而对于单一评价参数,如50%放热量或最高爆发压力所对应的曲轴转角位置,其评价指标没有唯一性.相对而言,采用有效膨胀比评价发动机的燃烧是最合理的.

In-Cylinder Heat Release Related Parameters and Their Influences on Thermal-Power Conversion Efficiency of an ICE

The parameters influencing the thermal-power conversion efficiency was analyzed based on the measured values of heat release rate and thermal efficiency.Some incomplete or incorrect conclusions are pointed out and the possible reasons are analyzed.It is not always true that large effective expansion ratio results in high indicated thermal efficiency.Similarly,it is not always true that the centre position of heat release curve should be as close to the TDC as possible.Also it is demonstrated that single characteristic parameters such as 50% burning position and peak pressure position,are not unique and may have multiply solutions when determining the highest thermal efficiency.Among those,the effective expansion ratio is identified as the most reasonable parameter.