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Due to the rapid development in advanced complex machinery, the analysis of torsional vibrations for multi-junction, multi-branch systems is becoming a subject of increasing interest. Torsional vibration may occur within an operation range in a rotating system and cause a serious failure in the machine. This is the case when an excitating frequency gets close to the natural frequency of the system. In this paper, an efficient and accurate method has been developed to calculate torsional natural frequencies of complex rotating systems. The method is used in designing a drive-train of a chassis dynamometer simulating a multi-junction, multi-branch rotating system. Natural frequencies and mode shapes of the drive-train have been determined and used for further development in the components of the system.

A set of experiments were conducted to evaluate the performance differences between a Low Heat Rejection Engine (LHRE) which is ceramic-insulated and a conventional baseline metal diesel engine which is water-cooled. Both engines were single cylinder, direct injection, and turbocharged. The objective of the study was to investigate the rate of heat release of these engines so that performance improvement procedures could be obtained. In this paper, the difference of the ignition delay between the two engines was determined. Two methods for improving the combustion process of the LHRE were studied: use of mixture fuels and increase the fuel injection rate. Both methods proved effective and reduced the fuel consumption rate of the LHRE.