The spray characteristics and, consequently, the success of the Diesel combustion process is strongly affected by the manner in which fuel is introduced in the combustion chamber. This work consists in studying the effect of needle motion of typical single-hole sac-type injectors on nozzle exit conditions. Three-dimensional moving mesh simulations have been carried out to calculate the injection process using cylindrical and conical nozzle geometries. The CFD analysis includes a study of the effect of cavitation on kinetic turbulent energy and velocity profiles. Results show that the flow within the nozzle and at the exit varies depending on the nozzle geometry and needle position. The model predicts clouds of cavitation that grow and exit the nozzle at low needle lifts. A kind of hysteresis in the development of the flow has also been observed between needle opening and closing. The existing correlation between turbulence and cavitation at the nozzle hole exit during the needle motion has been quantified.