喷水过程对内燃兰金循环发动机燃烧稳定性影响的试验研究

Experimental Study of Effect of Water Injection on Combustion Stability in Internal Combustion Rankine Cycle Engine

基于自主研发的内燃兰金循环发动机试验系统,采用曲轴转角压力变动系数法及其他传统分析方法相结合,对不同边界条件下内燃兰金循环燃烧稳定性进行试验分析研究。研究结果表明:曲轴转角压力变动系数可同时反映喷水造成的燃烧瞬态及循环整体波动。发动机在喷水的作用区间内产生明显的燃烧波动,燃烧相位后移,总体燃烧稳定性降低,但循环做功量增加。不同放热区间喷水所造成的瞬态燃烧波动幅值和形式皆有所不同,燃烧放热开始和结束后喷水将导致燃烧稳定性变差。提高氧气比例及适当减小喷水脉宽有利于提高发动机的燃烧稳定性。

In internal combustion Rankine cycle engine （ICRC） test bench, investigation of combustion stability in different boundary conditions was carried out by using a new method based on cylinder pressure variation coefficient per crank angle （CPVC/CA） and other traditional method. Results show that CPVC/CA value can reflect variations of both transient and entire combustion process. With obvious combustion variation occurring in water injection period combustion timing is postponed and cycle to cycle variations increase, but cyclic work also increases. Form and amplitude of transient combustion variation curves are different with different water injection timings, water injection before and after heat release process deteriorates combustion stability. Higher oxygen fraction and properly decreased water injection pulse width are beneficial to combustion stability.