Development of dispersion model of a two-stroke engine outboard plume

Abstract: - Many studies have shown that the conventional two-stroke engine produces more emissions than most other types of marine engines; this is due to the incorporation of the total-loss lubrication system into the design of the engine. As a result of stricter regulations recent developments in the outboard have seen the two stroke engine go from the convention oil/petrol mix to direct fuel injection. Direct fuel injection has the potential to significantly reduce two-stroke engine emissions by 75%-95%. Whilst this is a significant development there is still a number of conventional two-stroke engines operating, with the typical two-stroke engine having a life span of between 10-20 years; consequently the environment still experiencing the effects of unburned residual and partially burnt oil being emitted by the engine exhaust. The aim of this study was to investigate the properties of dispersion of a two stroke engine. This was achieved through the development of a computational fluid dynamics (CFD) model that would simulate the flow downstream of a propeller and be validated by experimental data obtained from literature. Data was taken at four major points downstream of the propeller hub on the z-axis, from those locations several sub points of data were recorded tangentially to the y-axis. The simulated data was validated against experimental data sourced from literature. The findings yielded a large variation between simulated model data and the five sets of data that were taken downstream of the propeller.