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Engine lubricating oil perform functions including wear reduction, friction reduction, piston cooling, corrosion prevention, cleaning pistons, preventing leakage and serving as a hydraulic media. Oil aeration is the entrapment of air into engine oil during operation. Aeration would affect oil density, viscosity and its sound velocity, with a detriment to such properties as lubricity, cooling and lubricating temperature, possibly resulting in worse engine working environment. In this paper, a new volume method with temperature compensation is introduced and proved to be indispensable. The measurement of oil aeration rate is performed with the main oil gallery of a four cylinder, turbocharged, high-speed diesel engine under different operating conditions. The temperature compensation is carried out for the measured oil aeration rate and the compensation effect evaluated. The variation of oil aeration rate with time after oil leaving the main oil gallery is also presented.

The level of boost pressure has a significant effect on optimizing the steady-state and transient performance of turbocharged diesel engines. However the problem of matching the wide speed range diesel engine and the high pressure turbocharging system has to be resolved. The regulated two-stage (RTS) system is an effective method to improve the fuel economy, transient response and smoke emissions. Compared with the difficult matching problem of the RTS system, the problem of boost pressure control is more complex due to the frequently changing operating conditions. To overcome the limitations of an open-loop control strategy, a closed-loop boost pressure control strategy was studied numerically using a mean value model of a diesel engine with RTS system. The system identification was conducted for the transient response from the turbine bypass opening command to the boost pressure.