Search Results

The concept of fuel-air mixture stratification is evaluated for a single cylinder, 200-cc CNG-fuelled SI engine with port gas injection (PGI). A detailed study based on three-dimensional computational fluid dynamics (CFD) modeling has been reported. Fuel-air stratification was observed in case of PGI compared to premixed fuel-air mixture formed by a conventional gas carburetor system. Overall stratification of more than 15% was observed for PGI between the rich and lean zones in the combustion chamber compared to less than 1% in case of premixed gas carburetor. It was observed that the gas injection location, direction, timing, duration and injection pressure have a significant effect on stratification pattern.

A computational method has been developed using finite volume method in conjunction with ALE (Arbitrary Lagrangian Eulerian) approach. The compressible, two-phase flow through the air-assisted injection system of a new, low-emission two-stroke engine under development is studied using this model. Good agreement is observed between computations and measurements of fuel consumption and pressure recovery in the air-assisted injection system of the current prototype. The crucial characteristics determining the performance of the injection system have been identified. The modeling shows possible reasons for the problems encountered by the prototype under certain operating conditions. Finally, the dependence of the performance of the injection system on certain crucial geometric parameters is studied. The present model would be a useful tool for the optimization of the overall system.