Presented in this paper is the relationship between intake pressure wave actions and the gen eral volumetric efficiency-speed characteristics of multi-cylinder engines. Coupling of primary pipes at the plenum produces a variable pressure boundary at the entry of primary pipes. The plenum pressure fluctuations directly superimpose on to the inlet Port pressure and in this way the volumetric efficiency curve is modified over that of the open primary pipe system. In speed domain the plenum pressure fluctuations experience a change of favorably to unfavorably phased, and the amplitude from significantly large to relatively small. Corresponding to that, the general volumetric efficiency characteristics of multi-cylinder engine can be divided into three sub-regions: (1) it is boosted over that of open primary pipe system; (2) it dips towards and down below that; (3) it follows the trend of that but with lower amplitude. Those three sub-regions are divided by the intake system tuning and de-tuned speeds which can be quite accurately predicted by a synthesis wave action model derived from this study.%本文论述的是根据台架试验及模拟计算结果得出的多缸发动机进气系统内压力波动与充气效率-转速特性的关系.各缸进气岐管在总管处的交汇产生了一非稳态的进气总管压力波动,该压力波直接叠加到进气岐管本身产生的压力波上从而导致了多缸发动机充气效率曲线在开口进气岐管基础上的变异.结果表明:在发动机转速域上,受进气岐管交汇处压力波动变化形态的影响,多缸发动机充气效率曲线可划分为3个区域:(1)充气效率幅值高于开口进气岐管系统;(2)充气效率曲线向开口进气岐管曲线转换;(3)两者具有相同的形态但前者幅值较低.上述3个子区域的边界即是其进气系统压力波的谐振转速及抵削转速.本文根据上述压力波动机理导出的压力波谐振转速及抵削转速的计算模型,与实验结果的吻合优于赫姆霍兹等常用模型.
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