DEVELOPMENT OF A PULSED ARC HEATER

A pulsed arc heater was designed, manufactured and installed in Centrospazio laboratory to equip a newly developed hypersonic, high-enthalpy, small-scale blow-down wind tunnel. The facility operates with air in the low to medium Reynolds number range (10 4 ∼10 6) and is capable of producing Mach 6 air flows, with a specific total enthalpy up to 3 MJ/kg, on an 60 mm effective diameter test section. The heater is run in a pulsed, quasi-steady mode, with test time ranging between 10 and 50 ms. The flow is directly heated by the electric arc established between two coaxial electrodes, powered by a large capacitor bank. A suitable plenum chamber placed just downstream of the discharge chamber allows the flow to reach thermochemical equilibrium before the expansion in the wind tunnel nozzle and enhances mixing therefore reducing radial gradients. A numerical model was developed to simulate the unsteady gasdynamic behavior of the arc heater: the model was used during the design phase to optimize the geometric and temporal parameters of the heater and to assess the hypersonic tunnel useful test time. Experimental results compare favorably with numerical predictions. More than 600 runs have been so far performed, demonstrating the heater reliability and capabilities