City Research Online

Abstract

Cavitation and cavitation-induced erosion highly depends on the thermodynamic properties of the fluid, which in turn affect the in-nozzle flow. However, many predictive models used today rely on constant properties or very simplified diesel surrogates. In this work, the diesel properties are predicted using a realistic four-component diesel surrogate, named J1D, which is compared with the traditionally used n-dodecane and then additised with n-hexane in amounts of 1% and 10%, named 1C6 and 10C6 respectively. The fuel property variation as function of pressure is modelled using the PC-SAFT EoS. The fluids are then used in simulations for a common rail 5-hole tip injector nozzle. The needle is assumed to be still at a lift of 105µm, which is representative of the lift reached during pilot injection. The injector operating pressure is 180MPa and the collector back pressure is 5MPa. The density of the bulk fluid is assumed to vary according to a barotropic-like scheme, following an isentropic expansion. Regarding the results from the simulations, the value of mass flow rate was proportional to the liquid density of the fluids. From the results, it appears that for substances with similar viscosity and density, such as J1D, 1C6 and 10C6 the vapour pressure is dominant in the cavitation production, as the greater the vapour pressure the greater the cavitation obtained. However, when the vapour pressure is comparable, such as that for J1D and n-dodecane, the difference in density and viscosity of the fluids seems to provide the cause for a greater vaporisation the lighter the fluid is. Despite its exploratory nature, this study offers some insight into the use of complex EoS and surrogate mixtures and their effect on cavitation and preferential vaporisation in diesel.

Publication Type:	Conference or Workshop Item (Paper)
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TL Motor vehicles. Aeronautics. Astronautics
Departments:	School of Science & Technology > Engineering

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