
The work is devoted to the construction of the basic equations of hydromechanics of two-phase flows with external mass transfer. The flow of a two-phase liquid is regarded as a continuum consisting of a large number of different groups of particles. The derivation of the phenomenological equations of motion is given taking into account both the external attached (or detachable) mass and the phase transitions within the medium. By applying fundamental conservation equations, the equations of mass, momentum and energy transfer for individual phases and the medium as a whole are obtained. It is shown that from the obtained systems of equations, in the absence of sources (sinks) of mass, momentum and energy, as a particular case, the known equations of hydromechanics of two-phase flows follow. The obtained equations of motion are valid for describing the component of the mixture and the medium with any physical and mechanical properties. For closure them, one can use thermodynamic and rheological equations of state, as well as expressions for the heat flux, interphase forces, the mass of phase transitions, and heat transfer between phases.