Non-Equilibrium Radiation from Shock-Heated Air
Abstract
A research program is described whose objectives include the quantitative measurement of the ultraviolet radiation behind strong shock waves in air, the identification of the radiating species and the determination of the mechanisms and rates that govern the emission. A shock tube was used to generate 3-4 km/s shock waves through air and oxygen nitrogen mixtures at initial pressures between 0.36-2.25 torr. The temporal gas-radiance profiles recorded radiometrically exhibited strong non-equilibrium overshoots, followed by decay to steady-state equilibrium. The dependence of the peak overshoot values on wave speed and pressure was measured and shown to scale with density. Emission spectra of the gas both in the overshoot region and the equilibrium region showed the NO gamma band system between 210 and 340 nm to be the dominant radiation source. The role of O2 Schumann-Runge radiation in this region was also studied; in pure O2 no overshoot was recorded. Infrared vibronic emission profiles were also measured and shown to be a description of the NO concentration growth. It was found that currently accepted rates for air ground-state chemistry do not predict the NO generation correctly. Finally, a simplified excitation model is suggested to describe the ultraviolet radiation behind the shock wave.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1991
- Accession Number
- ADA244905
Entities
People
- C. E. Treanor
- M. J. Williams
- W. H. Wurster
Organizations
- Calspan-University of Buffalo Research Center