Xavier LAMBOLEY, Laurent SERRE, Benjamin KHIAR, Nicolas DELLINGER
DOI Number: N/A
Conference number: HiSST-2025-079
The ONERA F4 hypersonic wind tunnel was commissioned in the early 1990s to support the European Space Shuttle program HERMES. Despite the cancellation of this program shortly afterwards, it has been used for many years to support studies of hypersonic reentry, both for Earth and Mars. More recently, it was used for scramjet propulsion tests in non water-viciated air. In this high-enthalpy wind tunnel, the hot flow source is generated using an electric arc chamber. This high-power arc (of the 150 MW class) heats a volume of a few litres of cold air at moderate pressure (between 30 and 80 bar) and brings it to the pressure and temperature levels required to simulate reentry conditions, with the ability to produce flows at several km/s. After a period of dormancy due to a slowdown in demand for tests in this speed range, the increasing focus on hypersonic high-enthalpy activities in France and worldwide in recent years justifies the reinstatement of this facility. This restart, which requires a partial renovation of the wind tunnel, also provides an opportunity to implement complementary activities aimed at better mastering the quality of the flow produced by the arc chamber. Indeed, the high-power electric arc heating process involves numerous physical phenomena, including the physics of the arc plasma, the Laplace forces that impact its dynamics, the interactions between the arc and the air, the dynamics of the internal air flow in the chamber, heat exchanges with the chamber walls and the degradation processes of the electrodes. The communication will first remind the design principles of the electrical architecture of the arc chamber, guided by the desire to minimise air pollution caused by electrode degradation. These architectural choices have been supported by large-scale experiments, which validated the principle of rotating the electric arc on its electrodes to limit degradation. In the second part, the article will present the work recently initiated at ONERA to start calculating the heating process in the arc chamber by coupling three in-house softwares: CEDRE for aero-thermochemistry and radiation, TARANIS for electromagnetism and MoDeTheC for material degradation processes. The first results obtained coupling these three codes will be presented. The final goal is to provide a better estimation of the flow properties when the pyrotechnic plug is activated to start the flow in the nozzle.