  We present results of hydrodynamical simulations of young supernova remnants.
To model the ejecta, we use several models (discussed in literature) of type Ia
supernova explosions with different abundances. Our hydro models are
one-dimensional and spherically symmetrical, but they take into account
ionization kinetics with all important processes. We include detailed
calculations for the X-ray emission, allowing for time-dependent ionization and
recombination. In particular, we compare the computed X-ray spectra with recent
XMM-Newton observations of the Tycho SN remnant. Our goal is to find the most
viable thermonuclear SN model that gives good fits to both these X-ray
observations and typical SN Ia light curves.
