  This work is devoted to a theoretical analysis of mass frequency response to
pressure oscillations of a spray of repetitively injected drops into a
combustion chamber. A single stationary spherical droplet continuously fed with
the same liquid fuel so that its volume remains constant despite the
evaporation, the so-called 'mean droplet' in the Heidmann analogy, represents
this vaporizing spray. The feeding is realized with a liquid-liquid heat
transfer coefficient by using a source point placed at the mean droplet centre,
in such a way that only radial thermal convection and conduction effects are
allowed inside the droplet during the process. This feeding procedure is now
viewed as a proper boundary condition that is a mixed or a generalized feeding
regime controlling the liquid fuel injection process into the combustion
chamber. Drawing upon a linear analysis based on the Rayleigh criterion, the
evaporating mass response factor is evaluated. Effects due to the variation of
the heat transfer coefficient and that of the process characteristic times are
analysed. An abrupt increase appears in the response when a fuel thermodynamic
coefficient approaches a particular value.
