Fluidic devices as fuel injectors for natural gas engines

A novel, fast switching, reliable, and economical fluidic gaseous fuel injector system designed for natural gas engines has been developed in this research. The system consists mainly of no-moving-part fluidic devices and piezo-electric controlling interfaces. The geometric parameters of a fluidic device seriously affect its performance. Traditionally, these parameters can only be optimised through "trial and error" exercise. In this research, a computer simulation model for the jet steady state attachment and dynamic switching has been developed. The good agreements between predicted results and experimental ones show that the model can not only explain the jet attaching and switching mechanism, but also optimise the design of geometric parameters of a fluidic device. The steady state and dynamic characteristics of the system were tested on a laboratory experimental rig. The results show that the system can handle the large gas volume flow rate required by natural gas engines and is capable of operating via pulse width modulation. A few typical commercial solenoid type gas injectors were also tested and the results were compared with those from the fluidic system. It was found that the fluidic gaseous fuel injector system has faster switching responses and smaller injection cycle-to-cycle variations.