| This master's thesis outlines the project investigating the effects of oxygenated fuel additives on flame propagation and engine performance. In the first of this two-part investigation, flame speeds, in a straight duct with a curved end section, were examined. The 172 cm straight section was followed by a 90° bend section and a 30 cm straight section. With propane as the fuel and emission zero air as the oxidizer, flame speeds, using equivalence ratios of 0.8, 1.0, and 1.1, were explored. In addition, a commercial propane fuel additive blend was introduced and its flame speed compared to instrument grade propane. The flame propagated through the duct in a fluctuating manner. The first flame inversions are predictable and repeatable. Subsequent flame inversions and pressure fluctuations corresponded to the natural frequencies of the duct. The overall flame speed showed an increase from lean to slightly rich mixtures for the equivalence ratios tested. The fuel blend did not significantly affect the characteristics of the flame propagation in the duct.; In the second part of the investigation, propane, mixed with a fuel additive, and air was introduced to a multi-cylinder engine. Because the fuel blend did not significantly affect the flame propagation characteristics in the duct, the additives were not expected to have an affect on the engine performance. Torque and power curves were successfully obtained, in addition to in-cylinder pressure measurements, to investigate a change in engine performance with fuel additives. Emission testing was preformed to determine the exhaust gas characteristics of propane with this fuel additive. The fuel additives were found not to significantly affect engine performance. |
