Development of Small Scale Arc-jet Facility OPG1

Abstract

A small-scale thermal arc-jet facility based on a 21.5 kW tungsten inert gas welding power supply has been developed. The design and simulations are presented here. The plasma generator is situated inside a vacuum vessel forming an Argon plasma with a mass flow rate of approximately 0.2 g/s. The vessel is evacuated by a series of pumps providing sufficient suction to keep the vessel below 125 Pa during continuous operation. The system is designed with regards to heat transfer and vacuum performance with the goal of keeping component temperatures pressures below critical values to prevent material failure and enable adequate vacuum. The thermal design of the plasma generator includes a water cooling circuit which keeps the copper anode below melting temperatures. A viscous reacting 2D axisymmetric simulation is carried out using Eilmer4 simulating the nozzle flow including the stagnation chamber and the free jet impinging onto a 40 mm diameter sphere-cone model. The simulations predict a maximum heat flux on the model surface of approximately 800 kW/m 2 when a plasma total temperature of 7400 K is assumed.

Optical temperature measurement in unsteady plasma free jet

“…Figure 2 displays a photograph of the OPG1 miniaturised plasma wind tunnel facility, which consists of a thermal arcjet plasma generator, an electrical power supply, a gas/water delivery system, a vacuum exhaust system with heat exchanger, a model mounting system, and a data acquisition system. The electrical power for the arc-jet is supplied by a Jasic TIG 500P AC/DC tungsten inert gas (TIG) welding power supply, which can generate up to 500A of current and up to 21.5 kW of power [26]. The plasma generator utilises a tungsten cathode with 2% thorium and a water-cooled copper nozzle as the anode.…”

Development of combined hypersonic test facility for aerothermodynamic testing

“…Conceptual design involves a dual facility setup using an arc-jet tunnel as a model preheating device in an impulse test facility [31]. A small-scale arc-jet facility, OPG1, for integration, has been developed [32]. However, subcomponents and a vertical movement system for dual-facility operation in the expansion tube mode of the T6 Stalker tunnel appear to be still under development.…”

Integration of Arc-jet in Impulse Facility for Hypervelocity Aerothermal Testing with Ablation

“…The system operation is recorded by a data acquisition system. More details are provided in a sister paper [32].…”

“…The integration will enable realistic preheated model experiments in hypervelocity flows. As a first step, a small-scale arcjet system [32] is currently being developed to examine the feasibility of a plasma generator, model movement system, and sub-component systems. This paper focusses on the dual-facility preheating methodology, including the expansion tube flow conditions and necessary considerations for the implementation within the facility test section.…”