In this study, a numerical model has been developed in AVL FIRE software to
perform investigation of Direct Natural Gas Injection into the cylinder of
Spark Ignition Internal Combustion Engines. In this regard two main parts
have been taken into consideration, aiming to convert an MPFI gasoline engine
to direct injection NG engine. In the first part of study multi-dimensional
numerical simulation of transient injection process, mixing and flow field
have been performed via three different validation cases in order to assure
the numerical model validity of results. Adaption of such a modeling was
found to be a challenging task because of required computational effort and
numerical instabilities. In all cases present results were found to have
excellent agreement with experimental and numerical results from literature.
In the second part, using the moving mesh capability the validated model has
been applied to methane Injection into the cylinder of a Direct Injection
engine. Five different piston head shapes along with two injector types have
been taken into consideration in investigations. A centrally mounted injector
location has been adapted to all cases. The effects of injection parameters,
combustion chamber geometry, injector type and engine RPM have been studied
on mixing of air-fuel inside cylinder. Based on the results, suitable
geometrical configuration for a NG DI Engine has been discussed.
Numerical investigation of natural gas direct injection properties and mixture formation in a spark ignition engine