  We study transitions of hadronic matter (HM) to 3-flavor quark matter (3QM)
locally, regarding the conversion processes as combustion and describing them
hydrodynamically. Not only the jump condition on both sides of the conversion
front but the structures inside the front are also considered by taking into
account what happens during the conversion processes on the time scale of weak
interactions as well as equations of state (EOS's) in the mixed phase. Under
the assumption that HM is metastable with their free energies being larger than
those of 3QM but smaller than those of 2-flavor quark matter (2QM), we consider
the transition via 2QM triggered by a rapid density rise in a shock wave. Based
on the results, we discuss which combustion modes (strong/weak detonation) may
be realized. HM is described by an EOS based on the relativistic mean field
theory and 2, 3QM's are approximated by the MIT bag model. We demonstrate for a
wide range of bag constant and strong coupling constant in this combination of
EOS's that the combustion may occur in the so-called endothermic regime, in
which the Hugoniot curve for combustion runs below the one for the shock wave
in P-V plane, and which has no terrestrial counter part. We find that strong
detonation always occurs. Depending on the EOS of quark matter (QM) as well as
the density of HM and the Mach number of the detonation front, deconfinement
from HM to 2QM is either completed or not completed in the shock wave. In the
latter case, which is more likely if the EOS of QM ensures that deconfinement
occurs above the nuclear saturation density and that the maximum mass of cold
quark stars is larger than two solar mass, the conversion continues further via
the mixing state of HM and 3QM on the time scale of weak interactions.
