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Abstract

An experimental investigation into the development of the expanding flame front in the combustion chamber was carried out using a CFR variable compression engine. Statistical analysis of the results indicated that the cyclical variation of the flame travel time followed a random distribution, but that the flame propagation velocity had a normal distribution. The cyclical variation of the flame propagation velocity was shown to be caused by cyclical variation in the air-fuel ratio. The experimental results were used in conjunction with a mathematical model of the combustion process to derive a correlation between the flame propagation speed and the turbulent Reynolds number.

The flame speed correlation was then used in a cycle synthesis to predict the mass burning rates of the charge. The model predicted successfully mass burning rates, cylinder pressures, temperature distribution in the burnt charge and exhaust emissions levels. The results suggested that turbulence was a secondary factor in flame propagation after the pre-propagation period, but may be more important at the initiation of the combustion. The experimental
results indicated that cyclical variations in cylinder pressure are produced by post-flame reactions. The thickness of the flame front was found to be significant and flame propagation followed the successive self-ignition theory more closely than the wrinkled flame front model.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TJ Mechanical engineering and machinery
Departments:	School of Science & Technology > Engineering School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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