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为了研究双燃料发动机燃烧的循环变动,在1台由电控共轨柴油机改装的甲醇-柴油双燃料发动机上进行4种工况的试验,发动机转速为1 400r/min,负荷率为40%(51.6kW),最佳引燃柴油喷油正时工况下改变掺烧比;转速为1 400r/min,掺烧比为21.2%,最佳引燃柴油喷油正时工况下改变负荷率;转矩为220N·m,掺烧比为39.6%,最佳引燃柴油喷油正时工况下改变发动机转速;转速为1 400r/min,负荷率为25%(32.84kW),掺烧比为37.2%的工况下改变喷油正时。研究了参数变化对双燃料发动机峰值压力pmax、峰值压力升高率(dp/dφ)max、峰值压力循环变动系数COVpmax和平均指示压力循环变动系数COVIMEP等参数的影响。研究结果表明:随着掺烧比增大,峰值压力有所减小,峰值压力升高率变大,在大掺烧比下,燃烧稳定性差,循环变动较大;随着负荷率增加,峰值压力增大,峰值压力升高率先增加后减小;随着转速升高,峰值压力变大,峰值压力升高率减小;负荷率增大或转速升高时,燃烧循环变动减小;随着引燃柴油喷油正时提前,峰值压力和峰值压力升高率均增加,小负荷、较大掺烧比工况下适当提前引燃柴油喷油正时可提高燃烧稳定性,但提前太多会引起爆震。
In order to study the cycling of dual-fuel engine combustion, four operating conditions were tested on a methanol-diesel dual-fuel engine modified by an electrically controlled common-rail diesel engine with an engine speed of 1,400 rpm and a load rate of 40% 51.6kW), the optimal ignition diesel fuel injection timing conditions change the mixing ratio; speed of 1 400r / min, mixing ratio of 21.2%, the best ignition diesel fuel injection load under the conditions of change in load ; Torque of 220N · m, mixing ratio of 39.6%, the best ignition diesel fuel injection timing conditions change the engine speed; speed of 1400r / min, the load rate of 25% (32.84kW), mixed with burning Than 37.2% of the conditions to change fuel injection timing. The effects of parameters on the parameters of peak pressure pmax, peak pressure increase dp / dφmax, peak pressure cycle COVpmax and average indicated pressure cycle COVIMEP were studied. The results show that with the increase of mixing ratio, the peak pressure decreases and the peak pressure increase rate increases. Under the high ratio of mixing ratio, the combustion stability is poor and the cycle variation is larger. With the increase of load ratio, the peak As the pressure increases, the peak pressure increases first and then decreases. As the rotational speed increases, the peak pressure increases and the peak pressure rise rate decreases. When the load rate increases or the rotational speed increases, the combustion cycle decreases. Ignition of diesel fuel injection timing ahead of time, the peak pressure and peak pressure rise rate are increased, small load, a larger ratio of combustion conditions appropriate ignition ahead of diesel fuel injection timing can improve combustion stability, but too early More will cause knocking.