Development of a Pulsed Arc Heater for a Hypersonic High Enthalpy Wind Tunnel

A pulsed arc heater was designed and manufactured at Centrospazio to equip a new hypersonic high-enthalpy blow-down wind tunnel capable of producing flows with a specific total enthalpy up to 2.5 MJ/kg. The heater mainly consists of two coaxial electrodes, separated by a constrictor, and a plenum chamber. The flow is heated by an electric arc ignited between the electrodes and sustained by the discharge of a large capacitor bank. The plenum chamber allows the flow to reach thermo-chemical equilibrium before the expansion in the wind tunnel nozzle. A numerical model was developed to simulate the unsteady behavior of the arc heater. The model was used during the design phase to optimize the geometrical and temporal parameters of the heater and the flow residence time. Experimental results from preliminary characterization compare favorably with numerical predictions. More than 600 runs have been performed up to date, demonstrating heater reliability and capabilities. A section area C 0 arc characteristic constant C p gas constant pressure specific heat C v gas constant volume specific heat I arc current k arc characteristic coefficient m arc characteristic coefficient & m mass flow rate M section Mach number p static pressure R gas constant (288 J kg-1 K-1 for air) t time T static temperature v flow velocity V chamber volume W th thermal input power ∆h enthalpy variation ∆V voltage difference ∆x electrodes distance ε arc efficiency γ gas specific heat ratio Γ internal energy function η restricted section discharge coefficient