  There are large differences in the proposed progenitor models for the Cas A
SNR. One of these differences is the presence or absence of a Wolf-Rayet (WR)
phase of the progenitor star. The mass loss history of the progenitor star
strongly affects the shape of the Supernova remnant (SNR). In this paper we
investigate whether the progenitor star of Cas A had a WR phase or not and how
long it may have lasted. We performed two-dimensional multi-species
hydrodynamical simulations of the CSM around the progenitor star for several WR
life times, each followed by the interaction of the supernova ejecta with the
CSM. We then looked at the influence of the length of the WR phase and compared
the results of the simulations with the observations of Cas A. The difference
in the structure of the CSM, for models with different WR life times, has a
strong impact on the resulting SNR. With an increasing WR life time the reverse
shock velocity of the SNR decreases and the range of observed velocities in the
shocked material increases. Furthermore, if a WR phase occurs, the remainders
of the WR shell will be visible in the resulting SNR. Comparing our results
with the observations suggests that the progenitor star of Cas A did not have a
WR phase. We also find that the quasi-stationary flocculi (QSF) in Cas A are
not consistent with the clumps from a WR shell that have been shocked and
accelerated by the interaction with the SN ejecta. We can also conclude that
for a SN explosion taking place in a CSM that is shaped by the wind during a
short < 15000 yr WR phase, the clumps from the WR shell will be visible inside
the SNR.
