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The use of twin-scroll turbocharger turbines has gained popularity in recent years. The main reason is its capability of isolating and preserving pulsating exhaust flow from engine cylinders of adjacent firing order, hence enabling more efficient pulse turbocharging. Asymmetrical twin-scroll turbines have been used to realize high pressure exhaust gas recirculation (EGR) using only one scroll while designing the other scroll for optimal scavenging. This research is based on a production asymmetrical turbocharger turbine designed for a heavy duty truck engine of Daimler AG. Even though there are number of studies on symmetrical twin entry scroll performance, a comprehensive modeling tool for asymmetrical twin-scroll turbines is yet to be found. This is particularly true for a meanline model, which is often used during the turbine preliminary design stage.

The purpose of this work was to gain a fundamental understanding of which fuel property parameters are responsible for particulate emission characteristics, associated with key intermediate behavior in the engine cylinder such as the fuel film and insufficient mixing. Accordingly, engine tests were carried out using various fuels having different volatility and chemical compositions under different coolant temperature conditions. In addition, a fundamental spray and film visualization analysis was also conducted using a constant volume vessel, assuming the engine test conditions. As for the physical effects, the test results showed that a low volatility fuel displayed high particulate number (PN) emissions when the injection timing was advanced. The fundamental test clearly showed that the amount of fuel film on the impingement plate increased under such operating conditions with a low volatility fuel.

Engine stop/start and cylinder deactivation are increasingly in use to improve fuel consumption of internal combustion engine in passenger cars. The stop/start technology switches off the engine to whenever the vehicle is at a stand-still, typically in a highly-congested area of an urban driving. The inherent issue with the implementation of stop/start technology in Southeast Asia, with tropical climate such as Malaysia, is the constant demand for the air-conditioning system. This inevitably reduces the duration of engine switch-off when the vehicle at stop and consequently nullifying the benefit of the stop/start system. On the other hand, cylinder deactivation technology improves the fuel consumption at certain conditions during low to medium vehicle speeds, when the engine is at part load operation only. This study evaluates the fuel economy benefit between the stop/start and cylinder deactivation technologies for the actual Kuala Lumpur urban driving conditions in Malaysia.

Throttling loss of downsized gasoline engines is significantly smaller than that of naturally aspirated counterparts. However, even the extremely downsized gasoline engine can still suffer a relatively large throttling loss when operating under part load conditions. Various de-throttling concepts have been proposed recently, such as using a FGT or VGT turbine on the intake as a de-throttling mechanism or applying valve throttling to control the charge airflow. Although they all can adjust the mass air flow without a throttle in regular use, an extra component or complicated control strategies have to be adopted. This paper will, for the first time, propose a de-throttling concept in a twin-charged gasoline engine with minimum modification of the existing system. The research engine model which this paper is based on is a 60% downsized 2.0L four cylinder gasoline demonstrator engine with both a supercharger and turbocharger on the intake.

In a turbocharged engine, preserving the maximum amount of exhaust pulse energy for turbine operation will result in improved low end torque and engine transient response. However, the exhaust flow entering the turbine is highly unsteady, and the presence of the turbine as a restriction in the exhaust flow results in a higher pressure at the cylinder exhaust ports and consequently poor scavenging. This leads to an increase in the amount of residual gas in the combustion chamber, compared to the naturally-aspirated equivalent, thereby increasing the tendency for engine knock. If the level of residual gas can be reduced and controlled, it should enable the engine to operate at a higher compression ratio, improving its thermal efficiency. This paper presents a method of turbocharger matching for reducing residual gas content in a turbocharged engine.

Cylinder deactivation has been utilized by vehicle manufacturers since the 80's to improve fuel consumption and exhaust emissions. Cylinder deactivation is achieved by cutting off fuel supply and ignition in some of the engine cylinders, while their inlet and outlet valves are fully closed. The vehicle demand during cylinder deactivation is sustained by only the firing cylinders, hence increasing their indicated power. Conventionally, half the number of cylinders are shut at certain driving conditions, which normally at the lower demand regime. An optimal strategy will ensure cylinder deactivation contributes to the fuel saving without compromising the vehicle drivability. Cylinder deactivation has been documented to generally improve fuel consumption between 6 to 25 %, depending on the type-approval test drive cycle. However, type-approval test has been reported to differ from the “real-world” fuel consumption values.

Emissions from motor vehicles are known to be the major contributor of air pollution. Pollutants that are commonly concerned and regulated for petrol engines are Hydrocarbons, Carbon Monoxide, Nitrogen Oxides and Particulate Matter. One of the most important factor that vary these pollutants is the engine operating condition such as cold start, low engine loads and high engine loads which are found during actual driving. In actual driving conditions, particularly in urban areas, vehicles regularly travel at idle, low or medium speeds which signify the engine part load operations. Thus urban driving carries a crucial weight on the overall vehicle fuel economy. Understanding the implications of urban driving conditions on fuel economy will allow for strategic application of key technologies such as cylinder deactivation in the efforts towards better efficiency.

The present investigation is centered around two motored research gasoline direct-injection engines, equipped with a pressure-swirl atomizer closely spaced with the centrally located spark plug. At first a Laser Doppler Velocimetry system was employed to characterize the in-cylinder airflow in one of the engines. A comparison was made to velocity profiles in a port-fuel injected engine of similar design characteristics, which revealed a different decay mechanism of the large-scale flow structure and associated higher turbulence levels in the pentroof of the cylinder. Second, images of the hollow cone fuel spray generated by the direct injector were recorded for three different injection timings in order to discuss the temporal and spatial development of the liquid phase in the engine cylinder in terms of its interaction with the gas motion.

This paper describes the development of a thin film rheometer able to measure the viscosity of lubricant films of the order of 200 μm thickness on flat, solid surfaces. The rheometer consists of a small cylinder mounted on a piezo bimorph which is divided electrically into two halves. When an AC voltage is applied to the one half of the piezo it causes the flat surface of the cylinder to oscillate in its own plane with an amplitude of a few microns. This motion produces an AC output from the other half of the piezo. The flat face of the cylinder is held parallel to an oily test surface and the latter is supported on a micrometer stage so that the gap between the two surfaces can be adjusted. As the gap is narrowed the oil film dampens the sinusoidal motion of the cylinder and the extent of this damping can be used to determine the viscosity of the oil film between the surfaces.