Numerical analysis of two-stroke engine with direct injection and jet ignition.

This thesis is carried out to evaluate the combustion evolution and the engine performance parameters of a two-stroke engine with direct injection and jet ignition.<br><br>Two-stroke engines are lightweight, simple to construct, high power- to- weight ratios and offer low cost to manufacture. The main problems with two-stroke engines are emissions and low fuel-efficiency.<br><br>This research used a two-stroke engine with crankcase scavenging. It also adopted an exhaust reed valve and lamellar intake, accommodating a high pressure direct injector as used in the latest two-stroke gasoline engines. The jet ignition device is replacing traditional spark plug. The main chamber and jet ignition use hydrogen as fuel. The jet ignition instrument is a pre-chamber accommodating a high-pressure injector operated with hydrogen fuel, and an 8 mm racing spark plug. The pre-chamber inside the jet ignition device is connected to the main combustion chamber through calibrated orifices. Lubrication is performed by selective oil injection where needed, rather than oil mixed with fuel.<br><br>A two-stroke engine CAD model has been designed by using 3D CAD software SolidWorks. Included are a jet ignition device, fuel injector, gas exchange system, combustion systems, lubricating system and other major engine components. The CFD simulations were performed in Star CCM+ to analyse the combustion evolution with hydrogen fuel in the cylinder from exhaust port closure to exhaust port opening. The obtained combustion rate results from CFD simulation were transferred into 1D software to investigate and analyse the performance of the two-stroke engine.<br><br>This research has shown good modelling results with efficiencies well in excess of 30% in the area of best engine operation, and reduced energy penalties when changing load and speed. The solution offers the opportunity to produce an efficient alternative to four- stroke engines with improved power density running an alternative fuel with better combustion properties and reduced pollution than traditional diesel and gasoline fuels.