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The paper is devoted to the analysis of the operating cycle of a high-pressure injection pump used in common rail systems. The investigation is based on experimental activities, and it is carried out in a novel pump set-up that allows measurements of the instantaneous pressure in the piston working chamber. A single plunger pump has been equipped with a piezo-resistive pressure transducer which allows for the measurement of the pressure signal during pump operation on a test rig. The paper describes the experimental set-up, the modified injection pump equipped with the pressure transducer, and the experimental tests carried out. Main results obtained using a standard commercial diesel fuel are discussed at first; secondly, the focus moves on to the use of an alternative fuel (biodiesel) whose features in terms of bulk modulus, viscosity, and density significantly differ from the reference fuel. Based on the characteristics of the pump operating cycle, the fuel suction and delivery processes are analyzed, pointing out how the used fuel type is reflected on them. The investigations are aimed at describing the operating characteristics of the pump, focusing the attention on those features playing a fundamental role on the global efficiency of the pump. The amplitudes of the pump-work phases, the ranges of pressure fluctuations, and the pressure-rise rates are quantified and reported, providing crucial indications for lumped parameter modeling and design activities in the field of current generation high-pressure injection pumps.

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The article presents a novel approach for the experimental characterization of hydraulic valves. The proposed methodology allows to capture the key layout of the valve, to study its characteristic flow rate and to visualize the flow that passes through it. In the wake of the experimental technique found in the literature, the novel approach introduces the use of an original test valve, briefly called “prismatic”. It represents an effective alternative to the so-called “Half-Cut Model” (HCM) proposed by Oshima and Ichikawa. The new test valve simplifies the experimental set-up and allows to visualize the whole internal flow field, providing full insight in both the inception and the spatial development of the cavitation. Moving from the HCM, the key features of the prismatic valve are preliminarily investigated and assessed by modelling, trough 3-D CFD simulations within OpenFOAM environment. Once the layout of prismatic valve is defined, the experimental assessment phase is carried out, highlighting its capability in research and development activities.

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