  Eulerian-Lagrangian simulations are conducted for two-dimensional Rotating
Detonative Combustion (RDC) fueled by partially prevaporized n-heptane sprays.
The influences of droplet diameter and total equivalence ratio on detonation
combustion and droplet dynamics are studied. It is found that small n-heptane
droplets (e.g. 5 um) are completely vaporized around the detonation wave, while
intermediate n-heptane droplets (e.g. 20 um) are consumed in or behind the
detonation wave, with the escaped ones be continuously evaporated and
deflagrated. The droplet distributions in the RDE combustor are significantly
affected by the droplet evaporation behaviors. Mixed premixed and non-premixed
combustion modes are seen in two-phase RDC. The detonated fuel fraction is high
when the droplet diameters are small or large, reaching its minimal value with
diameter being 20 um. The detonation propagation speed decreases with increased
droplet diameter and is almost constant when the diameter is larger (> 30 um).
The velocity deficits are 2-18% compared to the respective gaseous cases.
Moreover, the propagation speed increases as the total equivalence ratio
increases for the same droplet diameter. It is also found that the detonation
propagation speed and detonated fuel fraction are considerably affected by the
pre-vaporized gas equivalence ratio. The specific impulse first decreases for
cases with initial diameter less than 5 {\mu}m, then increases with droplet
diameter between 5 {\mu}m and 20 {\mu}m, and finally decreases with droplet
diameter larger than 20 {\mu}m.
