优化气道喷射方式的液压自由活塞发动机燃油效率研究

The study "Analysis and Optimization of Injection Methods for Two-Stroke Hydraulic Free Piston Engine with Airway Injection" aims to reduce fuel consumption when using airway injection in a two-stroke hydraulic free piston engine (HFPE). By placing the injector at the airway intake, a three-dimensional computational fluid dynamics simulation model was established using CONVERGE software to analyze the fuel injection process and the generation of the fuel-air mixture. The study focused on the effects of fuel injection phase, injection angle, and injector flow rate on the mixture formation process. The results showed that a smaller fuel injection angle and a later injection phase led to a higher fuel capture rate, reaching up to 99%, which was 39% higher than the fresh air capture rate. This resulted in a significant reduction in fuel consumption. However, excessively large or small fuel injection angles would deteriorate the atomization effectiveness of the fuel. The optimal fuel injection angle (43°-48° from the cylinder head normal direction) achieved the highest fuel atomization rate. Yet, an earlier injection phase would alter the actual flow direction of the fuel spray in the cylinder, leading to an increase in the formation of oil film on the cylinder wall and a decrease in the fuel atomization rate. Furthermore, a high-flow injector exhibited better fuel capture and atomization effects at the optimal injection angle. It also provided a wider range of effective injection phase intervals compared to a low-flow injector, offering greater injection flexibility. In conclusion, optimizing the fuel injection angle, phase, and injector flow rate is crucial in improving the fuel efficiency of a two-stroke HFPE with airway injection. This research provides valuable insights into the design and operation of such engines, contributing to the advancement of sustainable and energy-efficient transportation technology.