  We present similarity solutions for adiabatic bubbles that are blown by winds
having time independent mechanical luminosities and that are each mass-loaded
by the hydrodynamic ablation of distributed clumps. The mass loading is
`switched-on' at a specified radius (with free-expansion of the wind interior
to this point) and injects mass at a rate per unit volume proportional to
M^delta r^lambda where delta = 4/3 (1) if the flow is subsonic (supersonic)
with respect to the clumps. In the limit of negligible mass loading a
similarity solution found by Dyson (1973) for expansion into a smooth ambient
medium is recovered. The presence of mass loading heats the flow, which leads
to a reduction in the Mach number of the supersonic freely-expanding flow, and
weaker jump conditions across the inner shock. In solutions with large mass
loading, it is possible for the wind to connect directly to the contact
discontinuity without first passing through an inner shock. For a solution that
gives the mass of swept-up ambient gas to be less than the sum of the masses of
the wind and ablated material, lambda < -2. Maximum possible values for the
ratio of ablated mass to wind mass occur when mass loading starts very close to
the bubble center and when the flow is supersonic with respect to the clumps
over the entire bubble radius. The maximum temperature in the bubble often
occurs near the onset of mass loading, and in some cases can be many times
greater than the post-inner-shock temperature. Our solutions are relevant to eg
stellar wind-blown bubbles, galactic winds, etc. This work complements Pittard
et al (2001) where it was assumed that clumps were evaporated through
conductive energy transport.
