The paper considers the possibility of dispersion of liquid, that is, excitation of surface waves, the increase in amplitude of which leads to the separation of droplets from its surface due to the parametric instability of the liquid interface (Rayleigh instability) resulting from the modulation of the centrifugal acceleration due to the modulation of the velocity of the liquid entering the vortex chamber of the generator, as well as due to the instability due to the modulation of the shear rate (Kelvin-Helmholtz instability). In this paper, in the framework of a viscous, incompressible fluid, the possibility of dispersion of the liquid by variable pressure arising in the axial zone of the vortex chamber during the operation of the generator is investigated. Since the consideration is carried out for the case of incompressible fluid, the change in pressure is identified with a change in the density of the liquid. The solution is sought in a linear viscosity approximation using the Fourier transform in coordinates and the Laplace transform in time. It was found that the dispersion of the liquid in this case, that is, the instability of the liquid surface, is due to the same as in the work, parametric resonance and is described depending on the rate of fluid flow into the vortex chamber of the generator , the length of the vortex chamber, the type of the outlet (nozzle) Mathieu or Meissner equations. From the solution of these equations the boundaries of the liquid surface stability are obtained.