Flow Enthalpy of Nonequilibrium Plasma in 1 MW Arc-Heated Wind Tunnel

• Published in: AIAA journal 2021-01, Vol.59 (1), p.263-275
• Main Authors: Takahashi, Yusuke, Enoki, Naoya, Koike, Taiki, Tanaka, Mayuko, Yamada, Kazuhiko, Shimoda, Takayuki
• Format: Article
• Language: English
• Subjects: Discharge; Electric arcs; Emission spectra; Enthalpy; Heat flux; High temperature gases; Impact loads; Nitric oxide; Nonequilibrium plasmas; Nozzles; Numerical models; Plasma arc heating; Rotational spectra; Ultraviolet spectra; Wind tunnels
• ISSN: 0001-1452; 1533-385X
• DOI: 10.2514/1.J058407

The flow enthalpy of an arc-heated wind tunnel is an important parameter for reproducing planetary entry and performing heating tests. However, its distribution is insufficiently clarified, owing to complicated phenomena, such as arc discharge and supersonic expansion. In this paper, the authors assess the enthalpy of an arc-heated flow in a large-scale facility based on measurements and computational results. The flow enthalpy of high-temperature gases, which comprised thermal, chemical, kinetic, and pressure components, was reconstructed based on the measured rotational temperature, heat flux, and impact pressure, in addition to the computational science approach. The rotational temperature of nitric oxide molecules was obtained using emission spectroscopic measurements of band spectra in the near-ultraviolet range. A numerical model was developed and validated based on measured data. The results indicated that the model efficiently reproduced the arc discharge behavior in the heating section and the thermochemical nonequilibrium in the expansion section. It was discovered that the dominant components of the arc-heated flow in the test section were the chemical and kinetic components. The flow enthalpy exhibited a nonuniform distribution in the radial direction. The authors conclude that the flow enthalpy of the core is approximately 28  MJ/kg at the nozzle exit.