  Galactic winds play a crucial role in the ejection of the interstellar medium
(ISM) into intergalactic space. This study presents a model that classifies
possible transonic solutions of galactic winds in the gravitational potential
of the dark matter halo and stellar component under spherically symmetric and
steady assumptions. Our model includes injections of mass and energy resulting
from supernovae feedback along a flow line. The mass flux in galactic winds is
a critical factor in determining the acceleration process of the flow and
revealing the impact of galactic winds on galaxy evolution. We apply the
transonic galactic wind model to the observed outflow velocities of
star-forming galaxies to estimate the mass flux. Dividing the mass flux by the
star formation rate (SFR) yields the mass loading rate (and mass loading
factor), which indicates the entrainment effect of the ISM by the hot gas flow.
Our results demonstrate that the mass loading rate is inversely correlated with
galaxy mass and SFR. In less massive galaxies (stellar mass $\sim 10^{7-8}
M_\odot$), the mass loading rate exceeds unity, indicating effective ejection
of the ISM into intergalactic space. However, in massive galaxies (stellar mass
$\sim 10^{10-11} M_\odot$), the mass loading rate falls below unity, meaning
that the mass flux cannot exceed the injected mass by supernovae, thus
resulting in the ineffective ejection of the ISM.
