Development of Stable, High Power, High Pressure Arc Air Heaters for a Hypersonic Wind Tunnel

Research was performed on high voltage arc air heaters for hypersonic wind tunnels. Scaling laws and factors affecting them were established for the heaters. Two arc heater designs, capable of operating at two and four megawatts, respectively, were test d. Satisfactory operation was achieved at minimum operating specifications of one megawatt power to the air, 500 psi stagnation pressure, greater than 50% efficiency, contamination less than 0.1% in the effluent air jet, and running times longer than one minute. A plenum chamber for dual operation of two 2 megawatt arc air heaters was tested successfully. Heat losses in the plenum were less than 20% when operating at 200 psi pressure with 0.7 megawatt in the air effluent. Irregularities in brightness of an atmospheric pressure jet from a High Voltage arc air heater ranged from 6 to 30% rms. Variations in Mach number across the core of a 1-inch diameter free jet in a small wind tunnel were less than + or - 0.2 at Mach 5. Preliminary trials of alternating instead of direct current power were successful with the high voltage arc air heater and unsuccessful with the direct and toroidal arc air heaters. Design and operating data were projected for high voltage arc air heaters capable of operating at 40 and 100 megawatts of power with efficiencies of 50% or higher. The performance of three 40 megawatt heaters operating into a plenum chamber was also projected.