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Flame radiation has been recorded in an experiment within an operating D.I. diesel engine and the flame temperature has been estimated (a grey-body radiation has been assumed in interpreting the two-color method results). An indirect comparison of measurements has been done by an analysis of the Θ-number ratio of the mean bulk gas temperature Tg and the flame temperature Tf. Regression analysis of the author's experimental data revealed a linear Θ-Tg relation. More conclusive and physically grounded appears the Θ/Bo - time correlation (Bo - Boltzmann number). The similarity in shape of the Θ/Bo-time curves for different engine operating conditions provides facilities for the quantitative specification of the correlation searched.

Flame radiation intensity signals have been recorded in an experiment within an operating D.I. diesel engine. The applied methodology, experimental conditions and range as well as test result have been presented. Special Attention has been paid toward the cyclic irregularity of the photo-detector's response to the engine radiation signals obtained from the author's experiment, and a quantitative specification of that phenomenon has been developed. Statistical distribution of the flame radiation intensity tosses have been examined and the sample size effect on measurement accuracy as well as on result significance has been discussed.

Turbocharging diesel automotive engines has been a major approach toward improving their performance conditions and consequently, reducing the air pollution contributed by their exhaust emissions. The components of the turbocharging system discussed in this paper were compressors with improved performance characteristics, turbines with small inlet areas, waste-gate valve, and fuel control device (necessary for fueling schedule and engine speed control). Matching these components as a system and as well as to the engine was a major issue. The main purpose of the matching procedure was to develop and fit a turbocharging system with most suitable performance characteristics to the engine in order to obtain improved engine thermal operating conditions as well as an overall vehicle performance. An application example of the concept was performed on an eight-cylinder, direct injection, heavy duty diesel automotive engine predicted for urban city bus.