DESIGN AND CALIBRATION OF AN ARC-HEATED ,HYPERSONIC, LOW-DENSITY WIND TUNNEL

摘要

The design and calibration of an arc-heated gas jet that produces a continuous flow in a wind tunnel at a Mach number of 4 to 5 are de¬scribed. Uniform flow conditions prevail over a central 1-inch-diameter core at static pressures of 0.05 to 0.1 millimeter of mercury with en¬thalpies up to 4300 Btu per pound for nitrogen and 1100 Btu per pound for argon. These conditions correspond to stagnation temperatures up to 9000° R, to altitudes of about 200,000 feet, and to velocities of about 11,000 feet per second.nDetails are given for design features that produce stability of a confined arc over long periods of time with arc transfer efficiencies up to 50 percent. For nitrogen, the downstream gas jet is about 5 percent dissociated, and the vibrational energy is in equilibrium before the gas enters the nozzle throat.nMass-averaged total downstream enthalpies, computed from profile measurements made with total-pressure probes and several stagnation-point heat-transfer probes of similar design about l/4 inch downstream of the nozzle exit, agree within 10 percent with enthalpies computed from electric-power input, mass-flow rates, and coolant temperature rise. The enthalpies determined in the center core are about 20 percent higher.