Abstract
Two-dimensional model was used to analyze characteristics of natural gas jet in a constant volume chamber. Three-dimensional combustion chamber model was used to study mixture stratification for direct injection of natural gas. In the simulation, the gases are assumed to be compressible, unsteady and turbulent flow based on standard k-å model. Model validation was examined by comparing with experimental results. The penetration length of the gas jet along the axis of injection and the shape of fuel jet were obtained from the Schlieren photographs. The results showed that these simulation models could provide adequate agreements with experimental results in range of conditions considered. A new piston cavity for stratified charge natural gas direct injection engine was developed based on results of simulation.