Abstract : This is an MSc report to develop a turbulent combustion model and couple it with engine simulation software to improve its predictive capability. For liquid or gaseous fuels one of the most important quantities is the velocity at which the flame front propagates normal to itself and relative to the flow into the unburned mixture. In a non-turbulent mixture, flame propagation is laminar and the flame has smooth surface. However, in a turbulent flow field, the flame front is no longer smooth and the reaction zone is thicker than that in laminar case. According to Damkohler theory, the increase in flame front area due to turbulence causes to increase the flame speed. However, recent studies show that the ratio of turbulent to laminar flame speed (ST/SL) depends on both the relative increase in flame surface area as a result of turbulence, and the relative drop in local flame speed as a result of stretching. The proposed research will empirically study the effect of stretching on flame speed under engine-like conditions and develop a model for flame speed base on that. For this reason, flame surface area and speed will be found by processing high speed images which are taken from flame inside cylinder. Then, the developed combustion model will be coupled with GT-Power engine simulation software in order to, first, evaluate the developed model and then, improve the GT-Power predictive combustion capability. To specify initial conditions correctly, the initial swirl and tumble values will be measured by using the steady-flow-rig method. Finally, to verify the simulation and developed turbulent combustion model, a V-twin, four-stroke, air cooled, ECH 749 Kohler engine will be used.

Various combinations of commercially available technologies could greatly reduce fuel consumption in passenger cars, sport-utility vehicles, minivans, and other light-duty vehicles without compromising vehicle performance or safety. Assessment of Technologies for Improving Light Duty Vehicle Fuel Economy estimates the potential fuel savings and costs to consumers of available technology combinations for three types of engines: spark-ignition gasoline, compression-ignition diesel, and hybrid. According to its estimates, adopting the full combination of improved technologies in medium and large cars and pickup trucks with spark-ignition engines could reduce fuel consumption by 29 percent at an additional cost of $2,200 to the consumer. Replacing spark-ignition engines with diesel engines and components would yield fuel savings of about 37 percent at an added cost of approximately $5,900 per vehicle, and replacing spark-ignition engines with hybrid engines and components would reduce fuel consumption by 43 percent at an increase of $6,000 per vehicle. The book focuses on fuel consumption-the amount of fuel consumed in a given driving distance-because energy savings are directly related to the amount of fuel used. In contrast, fuel economy measures how far a vehicle will travel with a gallon of fuel. Because fuel consumption data indicate money saved on fuel purchases and reductions in carbon dioxide emissions, the book finds that vehicle stickers should provide consumers with fuel consumption data in addition to fuel economy information.