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This paper presents an experimental study of the correlation between rail-to-injector connection pipe geometry (3 lengths and 3 diameters) and pressure oscillation characteristics (amplitudes, mean pressure drop, frequency, damping of the oscillation) and injected volume, respectively. The injection input parameters are based on a single injection with 5 pressure levels and 4 injection durations. Pressure recordings are available for the injector inlet, an adjacent injector port, and the rail. The study shows that the connection pipe geometry may have a considerable impact on the analyzed variables. Particularly interesting appears the unexpected bond between pipe diameter and oscillation frequency.

One way to improve diesel engine performance and to reduce emissions is improving power density and combustion cycle efficiency. It can be done by increasing combustion pressure and engine speed drastically and also by improving the controllability of the engine. Besides of the fuel injection system the key element in improving controllability is the valvetrain. Extreme combustion pressure and engine speed set special requirements for valvetrain design. As the pressure and engine speed are increased the load on the valve actuation mechanism becomes higher because of the higher pressure acting on the valve plate and also the need for higher acceleration. High instantaneous power required due to high load makes electrohydraulic system a natural choice for actuation mechanism. An electrohydraulic camless valvetrain (IHAflex) for extreme value engine (EVE), developed by Institute of Hydraulics and Automation of Tampere University of Technology, uses neither cams, nor retainer springs.

This research work deals with common rail fuel injection system of a diesel engine. Fuel injection system tuning is important to provide similar conditions to each injections. This means that the timing of the fuel injection and control of the amount of the fuel during the injection have to be done accurately. The pressure oscillations might disturb the behaviour of the fuel injection event if the system is not properly designed or tuned. In this work the pressure oscillations and how to prevent them were studied. The study started with the modelling of the components of the Common Rail fuel injection system. The simulation results were verified to measured ones. After the fluid properties were also taken into account the correspondense were acceptable. The simulation model were used for studying the performance a Common Rail fuel injection system. This study deals also with the fluid properties in high pressure.

This paper investigates the source of pressure fluctuations in a common rail (CR) system for high speed diesel engines as a function of injection parameters and system design (pipe between rail and injector). The pressure values are recorded experimentally at the inlet of the injector. In addition, a simulation model has been developed. The parameters include: injection pressure (800 to 1500 bar) and duration (0.4 to 1 ms), and connection pipe length (180 to 500 mm) and diameter (2.2 to 3 mm). The model shows good agreement with the measurements. The study shows that all parameters have an effect on the pressure oscillation at the injector inlet.