Numerical Simulation For Fuel Gas Injection Of A Direct Injection Natural Gas Engine

With the development of direct injection technology, the combination of nature gas and direct injection technology has become a new technical approach, direct injection gas engine can improve fuel economy and power output, and avoid soot emissions in GDI engine. For direct injection engine, the fuel injection and mixing with the air is considered the most important process. Numerical simulation of direct injection nature gas engine can helps to enrich and develop the jet injection model, create in-depth understanding of injection gas injection and mixing process, it also lays the foundation for further research on numerical simulation of combustion process of DING and dual fuel engine working work.In this paper, fuel injection in direct injection nature gas engine was researched with the open source CFD program KIVA-3V. Firstly, a hybrid approach combining phenomenological submodel and dimensional flow model were studied. Secondly, the hybrid approach was realized, fuel gas injection simulation model in DING was further established. On the basis of the aforementioned work, natural gas jet development features was researched, and the impact of the main cylinder flow field parameters and injection parameters on the injection process was analyzed deeply.Phenomenological model subroutine was developed, a mixed phenomenology and multi-dimensional flow model was established, dynamic characteristics of natural gas jet development process were revealed, and the influences of flow field parameters in engine and injection parameters on gas injection were studied. It’s found that, subsonic and supersonic gas jet can simulated accurately by the hybrid model. The development law of CH4concentration, velocity, turbulent kinetic energy, pressure and temperature fields have similarities and great differences. And cylinder pressure, the initial swirl ratio, injection timing, injection pressure and injection nozzle diameter has a significant impact on natural gas development and stratified mixture formation rate.