In this study, the variation of the flow field in Hydro-reactive engine combustor was numerically studiedthrough 2-dimensional axisymmetric model with aluminum and heated water vapor. For calculating all velocityfields, compressible Navier-Stokes equation was used with Pre-conditioning. AUSM+up(p) method was usedto exactly calculate mass flow in the control volume. As using SST model that is a turbulent model, the resulthad high accuracy for free stream and the flow near the wall. The effects of the temperature, variation of theflow field and distribution of chemical products on inject angle of heated water vapor were studied.