Numerical Analysis of the Effects of Needle Lift and Seat on the Cavitation Flow in the Diesel Injector Nozzle

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Abstract

In this paper, cavitation flow inside the injector nozzle has been numerically simulated using ANSYS Fluent v15. The validations were performed with experimental results of Winkhofler et al. (2001). The calculated results from the three dimensional numerical simulation of cavitating flow in the nozzle with mixture multi-phase cavitating flow model have good agreement with the experimental data. Several important parameters such as mass flow rate and velocity profiles were used for the validations. The cavitation model used in the simulations is Schnerr and Sauer cavitation model. Due to high Reynolds numbers, turbulence effects have been taken into account by RANS methods using RNG k–emodel. PRESTO discretization method is used for pressure equation and second upwind discretization method is used for momentum equation. The discharge coefficient is computed for several cavitation numbers and needle lift. The results show that the needle lift and seat shape of the nozzle have a strong influence on the volume fraction of diesel vapor and the discharge coefficient in the nozzle.

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