We have conducted inviscid flow computations of wave drag reduction by a single pulse energy deposition in a supersonic flowfield around a blunt body. The wave drag for a sphere is reduced as a result of interaction between a blast wave produced by the energy deposition and the bow shock formed in front of the sphere. Effects of deposited energy and deposition location on energy reduction were examined by parametric studies. From obtained results, we have refined on parameters utilizing the baroclinic source term in vorticity equation. The amount of energy reduction analytically estimated by the baroclinic vortex has a linear dependence with low-density radius of the blast wave and is proportional to the square of freestream Mach number as well as the computational result.