We have performed 3D hydrodynamic simulations of a symmetrical jet ejection following previous works (Raga et al. 2009, Riera et al. 2014, Velázquez et al. 2014). The jet is emitted from a binary system in elliptical orbit, and its direction changes describing a precession cone. We have considered that the jet has a time-dependence density ejection or a time-dependence velocity ejection, in order to propose an alternative model to explain the morphology of PPNe’s. Also in our description we have included the effect of the photoionization of the central source. From numerical results, synthetic Hα maps were obtained, and a proper motion study were carried out. We found that the photoionization has an important effect on the case with variation density resulting in a increse in the Hα emission.