Spectroscopic Analysis of NO Band Emissions from Arc-Heated Air Flows in a 750kW Arc-Heated Wind Tunnel.

摘要

Spectroscopic measurements of arc-heated high enthalpy air free streams were carried out in a 750 kW arc-heated wind tunnel. A 50cm Acton SpectraPro 500iu spectrograph with Princeton Instrument 576G-1 ICCD detector was used to obtain emission spectra in the wavelength range from 190nm to 900nm. Major spectral features identified were the vibrational of NO gamma delta and epsilon band systems in the UV region. All the vibrational bands observed show only an upper vibrational level of v'=0. The NO bands were analyzed and synthetic spectra built based on the detailed energy level structure of NO and spectral line profile. The extent of agreement between synthetic and high resolution experimental spectra was examined to determine rotational temperatures, using a spectral profile matching method. Vibrational temperatures could not be determined by experiment due to the lack vibrational bands with v' greater than 0. Examining problems such as the lack of Beta band system and v' greater than 0 bands of other band systems and, unexpectedly weak intensities of the E band systems would be of use in clarifying details of nonequilibrium energy transfer mechanisms in the flow.