Accession Number:

ADA244905

Title:

Non-Equilibrium Radiation from Shock-Heated Air

Descriptive Note:

Final rept. 1 Jul 1988-30 Jun 1991,

Corporate Author:

CALSPAN UB RESEARCH CENTER BUFFALO NY

Report Date:

1991-07-01

Pagination or Media Count:

96.0

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 kms 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.

Subject Categories:

  • Atmospheric Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE