对置活塞二冲程发动机耗气特性研究

Study on the Gas Consumption Characteristics of an Opposed-Piston Two-Stroke Engine

针对对置活塞二冲程发动机对扫气效率优化和功率目标匹配的需求，基于试验和理论分析研究了发动机的耗气特性。采用试验数据和数学模型联合得到发动机的等效流量系数，分析了不同进排气参数、气口开启面积等对发动机耗气量的影响规律。研究结果表明：耗气量只由扫气压力、排气压力和绝热效率三个因素决定，与发动机转速无关；该发动机的等效流量系数近似等于0．272；不同曲轴转角所对应的流量系数与气口开启面积有关，当气口开启面积增加到一定值（4500～4668mm2），并继续增加时流量系数保持不变。

For the requirements of the scavenging efficiency optimization and power target matching of opposed-piston two-stroke engine, the gas consumption characteristics was researched based on experiments and theoretical analysis. The experimental data and mathematical model were used to obtain the equivalent flow coefficient of an opposed-piston two-stroke engine. The influence of the engine port opening area and the different inlet and exhaust parameters, such as intake pressure, exhaust pressure and adiabatic efficiency, on gas consumption of the engine was analyzed. The result reveals that： （1） the gas consumption depends only on intake pressure, exhaust pressure and adiabatic efficiency, and has nothing to do with the engine speed; （2） the engine equivalent flow coefficient is approximately equal to 0. 272; （3） the flow coefficient corresponding to the crankshaft angle is related with the port opening area of the engine. When the port opening area reaches to a certain value （4500~4668mm2）, and continues to increased, the flow coefficient will remain constant.