The scavenging process of two stroke engine includes free exhaust, scavenging, and post intake process, which clears the burned gas in cylinder and suctions the fresh air for next cycle. The gas exchange process of Opposed-Piston Two-Stroke (OP2S) engine with gasoline direct injection (GDI) engine is a uniflow scavenging method between intake port and exhaust port. In order to investigate the characteristics of the gas exchange process in OP2S-GDI engine, a specific tracer gas method (TGM) was developed and the experiments were carried out to analyze the gas exchange performance under different intake and exhaust conditions and opposed-piston movement rule. The results show that gas exchange performance and trapped gas mass are significantly influenced by intake pressure and exhaust pressure. And it has a positive effect on the scavenging efficiency and the trapped air mass. Scavenging efficiency and trapped air mass are almost independent of pressure drop when the delivery ratio exceeds 1.4. Consequently, the delivery ratio ranges from 0.5 to 1.4 is chosen to achieve an optimization of steady running and minimum pump loss. The opposed piston motion phase difference only affects the scavenging timing. Scavenging performance is mainly influenced by scavenging timing and scavenging duration. With the increased phase difference of piston motion, the scavenging efficiency and delivery ratio increased gradually, the trapping efficiency would increase first and decrease then and reaches its maximum at 14°CA.

二冲程发动机的扫气过程包括自由排气、扫气和后进气过程，清除气缸内已燃烧的气体，吸入下一个循环的新鲜空气。对置活塞二冲程 (OP2S) 发动机与汽油直喷 (GDI) 发动机的换气过程是进气口和排气口之间的单流扫气方法。为研究OP2S-GDI发动机换气过程的特点，开发了一种特定示踪气体法（TGM），并进行了实验分析了不同进排气工况和对置活塞运动下的换气性能。规则。结果表明，进气压力和排气压力显着影响气体交换性能和截留气体质量。它对扫气效率和截留气团有积极的影响。当输送比超过 1.4 时，扫气效率和截留空气质量几乎与压降无关。因此，选择范围从 0.5 到 1.4 的输送比以实现稳定运行和最小泵损失的优化。对置活塞运动相位差仅影响扫气正时。扫气性能主要受扫气时机和扫气持续时间的影响。随着活塞运动相位差的增加，扫气效率和输送比逐渐增加，捕集效率先升高后降低，在14°CA时达到最大值。当输送比超过 1.4 时，扫气效率和截留空气质量几乎与压降无关。因此，选择范围从 0.5 到 1.4 的输送比以实现稳定运行和最小泵损失的优化。对置活塞运动相位差仅影响扫气正时。扫气性能主要受扫气时机和扫气持续时间的影响。随着活塞运动相位差的增加，扫气效率和输送比逐渐增加，捕集效率先升高后降低，在14°CA时达到最大值。当输送比超过 1.4 时，扫气效率和截留空气质量几乎与压降无关。因此，选择范围从 0.5 到 1.4 的输送比以实现稳定运行和最小泵损失的优化。对置活塞运动相位差仅影响扫气正时。扫气性能主要受扫气时机和扫气持续时间的影响。随着活塞运动相位差的增加，扫气效率和输送比逐渐增加，捕集效率先升高后降低，在14°CA时达到最大值。对置活塞运动相位差仅影响扫气正时。扫气性能主要受扫气时机和扫气持续时间的影响。随着活塞运动相位差的增加，扫气效率和输送比逐渐增加，捕集效率先升高后降低，在14°CA时达到最大值。对置活塞运动相位差仅影响扫气正时。扫气性能主要受扫气时机和扫气持续时间的影响。随着活塞运动相位差的增加，扫气效率和输送比逐渐增加，捕集效率先升高后降低，在14°CA时达到最大值。