Observation of Nonequilibrium Radiation behind Strong Shock Waves in Low-density Air

Article type: Research Article

Authors: Morioka, T. | Sakurai, N. | Maeno, K. | Honma, H.

Affiliations: Graduate School of Science and Technology, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

Abstract: Nonequilibrium radiation phenomena behind strong shock waves in low-density air are observed by using a couple of CCD camera systems in a shock tube experiment. The simultaneous observation for total radiation and its spectral radiation is carried out in order to elucidate space-dependent contribution of an individual radiation spectrum to the total radiation intensity. The results are shown for the shock velocity range from 9.0 km/s to 12.1 km/s at the initial pressure 13.3 Pa. Wavelength range is selected from 300 nm to 445 nm to investigate mainly the contributions from UV radiation. It is found that the band spectra due to the molecular species N_2^+ and CN mainly contribute to the first-peak, while the spectra due to the atomic species O^+ and N mainly contribute to the formation of the second-peak. It is also found that the Balmer series in H spectra strongly contributes to the second-peak. The radiation along the tube wall surfaces is composed of the same constituents as those around the tube axis as well as the spectra coming from the impurities.

Keywords: strong shock wave, radiation, spectroscopy

Journal: Journal of Visualization, vol. 3, no. 1, pp. 51-61, 2000