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An investigation on the sequential turbocharging (ST) of a Kelvin TFSC6 medium speed diesel engine developing 320 kW at 1200 r/min is reported in this paper. The sequential turbocharging (ST) system, utilising turbochargers of unequal size, resulted in significant improvement when compared with previously designed systems. The engine test results show that the new ST system improves the engine performance at both high and low speeds except, at or near to, the ‘transfer’ speed. The engine low speed performance is improved with fuel saving of up to 7 g/kwh for the 1st sequence. However, the improvement of the high engine speed performance at the 2nd sequence was limited by some boost air leakage from a flexible connecting pipe from the peak unit compressor outlet to the intercooler inlet. An optimised sequence transfer control mode is also proposed in this research.

A computer based data acquisition and control system has been developed for IC engine research at Kelvin Engine Technology Unit (KETU). A computer program was designed and compiled using a graphical programming language known as LabVIEW for engine experimental studies and monitoring. A self-adaptive auto-load setting, specifically designed for an early type of dynamometer, is presented for engine operational control by computer. Both engine overall performance and dynamic pressure measurement results can be processed, analysed and displayed graphically during the engine test period. These methods have resulted in a compact and effective engine experimental study system.

In order to assist engine design through a better understanding of the direct-fuel-injection of two-stroke gasoline engines, a simulation model has been established using a multidimensional CFD code. Two-phase flow in the changing geometry of the engine was evaluated. To obtain a developed fluid flow field for the fuel-injection cases, two full engine cycles were computed. Two cases were analyzed, one with the injector at the cylinder head and the other at the cylinder side wall. The gas flow field, fuel droplet distribution and fuel vapor concentration were obtained and compared for the two cases.