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This paper deals with the analysis of the interaction between solid contamination and internal geometry in hydraulic conical and spherical poppet valves, performed through a non-dimensional, axis-symmetric CFD analysis of their internal flow. The information coming from the flow field solution is used to identify regions having higher probability to be impacted by particles dragged by the fluid, and to estimate the erosion potential of solid particles having different size. The value of the kinetic energy of particles approaching the walls of the geometric domain is used to estimate the amount of material potentially eroded by impacting particles, and to provide a potential correlation between ISO 4406 and NAS 1638 solid contamination level classification. The long-term target is a numerical estimation of service life in hydraulic components.

This paper focuses on the application of the fast image processing to the internal flow field characterization, and on the set up of the experimental methodology which enables the use of direct visualization techniques to fluid power components. More in details, the design of both a low pressure hydraulic power unit and a number of polymethyl-methacrylate (PMMA) transparent prototypes are firstly outlined. Afterward, the fast image processing is involved and, to highlight the usefulness of the fast image processing in the analysis of multi-phase multi-component effluxes, solid particle injection and air bubble inoculation are used. Finally, some of the results obtained using a progressive, mid resolution, high frame rate and monochrome digital camera are shown, and the internal flow evolution is qualitatively analyzed.

Oxygen enriched air (EA) is a well known industrial mixture in which the content of oxygen is higher respect the atmospheric one, in the range 22-35%. Oxygen EA can be obtained by desorption from water, taking advantage of the higher oxygen solubility in water compared to the nitrogen one, since the Henry constants of this two gases are different. The production of EA by this new approach was already studied by experimental runs and theoretical considerations. New results using salt water are reported. EA promoted combustion is considered as one of the most interesting technologies to improve the performance in diesel engines and to simultaneously control and reduce pollution. This paper explores, by means of 3-dimensional computational fluid dynamics simulations, the effects of EA on the performance and exhaust emissions of a high-speed direct-injection diesel engine.