The drag reduction of blunt body in hypersonic flow via plasma injection has been investigated by a combined experimental and computational effort. The counterflow plasma jet generated by a plasma torch has a vibrionic temperature of 4400 K, an electronic temperature around 20,000 K, and electron density greater than 3 x 10(12)/cm(3). At a fixed injection stagnation pressure and in the absence of an applied magnetic field, the plasma injection actually increases drag above that of room-temperature air due to a decreased mass flow rate at the elevated temperature. However, at an identical mass flow rate, the plasma injection reveals a greater drag reduction than the room-temperature air counterpart through thermal energy deposition. From experimental measurements, an overwhelming major portion of the drag reduction is derived from the viscous-inviscid interaction of the counterflow jet and thermal energy deposition. The numerical results of Navier-Stokes equations with a local equilibrium plasma composition also confirm this observation. References: 34
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