Experimental investigation of an electric arc air-spike in mach 10 flow with preliminary drag measurements

The effects of an arc discharge to create an Air-Spike in a hypersonic flow are currently being studied in the Rensselaer Polytechnic Institute 24-inch Hypersonic Shock Tunnel (RPI HST), modeled computationally, and compared to existing theory. The arc is a high current car battery array-driven, 75-kilowatt peak, self-sustaining electrical discharge in a Mach 10, 260 psia stagnation pressure, and 560 K stagnation temperature flow. In this low enthalpy, "ideal gas," condition, schlieren photographs are taken of the apparatus with and without a downstream blunt body, with varying arc powers. Blunt body drag measurements are also made with a fast-response accelerometer, both with and without the arc to establish a correlation between arc power and body drag. The computational effort employs the Euler gasdynamic equations to represent a heat source in flow conditions and geometries identical to those tested in the RPI HST. These two results are then compared to early Air-Spike theoretical predictions to qualitatively validate the CFD code and gain a better perspective on the loss mechanisms involved in the experiment.