OH rotational temperature and concentration measurements in a supersonic jet
- Sandia National Labs., Livermore, CA (United States)
- California Univ., San Diego, La Jolla, CA (United States). Center for Energy and Combustion Research
Axial and radial profiles of the rotational temperature and concentration of the OH molecule in an axi-symmetric combustion- driven supersonic free jet were measured over a Mach number range from M=1.5 to 7.5 and number density from 10{sup 12} to 10{sup 14}cm{sup {minus}3}. The free jet was produced from the combustion products of a low-pressure (51.8-torr) H{sub 2}/O{sub 2}Ar flame ({Phi}=1.09) expanded from a converging quartz nozzle into a vacuum. The temperature and concentration of the OH molecule were measured via laser-induced fluorescence (LIF) from the R{sub 1}(3), R{sub 1}(4), and R{sub 1}(7) lines in the (1.0) band of the A {sup 2}{Sigma} {minus} X {sup 2}{Pi} transition with detection in the (1, 1) band. The temperature was measured using a two-line technique. An empirical model of the fluorescence yield was developed using time-resolved fluorescence quenching rates measured on the jet axis to correct the fluorescence signals for quenching effects. The predicted fluorescence yield increased by a factor of 23 along the jet axis as the temperature decreased from 772 K to 100 K, primarily due to the corresponding decrease in number density for this isentropic expansion. The increase in fluorescence yield due to the density decrease was reduced due to an increase in the collisional cross-section following a T{sup {minus}0.5} temperature dependence. The fluorescence yield increased with increasing rotational quantum number. At a temperature of 400 K, the fluorescence yield increased by 30-percent from N{prime}=5 to N{prime}=8. The measured OH rotational temperature and concentration profiles were in good agreement with the predictions of a method of characteristics solution for the behavior of the supersonic free jet. 11 refs., 6 figs., 1 fig.
- Research Organization:
- Sandia National Labs., Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States); California Univ., Berkeley, CA (United States)
- DOE Contract Number:
- AC04-76DR00789
- OSTI ID:
- 10114901
- Report Number(s):
- SAND-91-8733; CONF-920707-10; ON: DE92006700
- Resource Relation:
- Conference: 24. international symposium on combustion,Sydney (Australia),5-10 Jul 1992; Other Information: PBD: [1991]
- Country of Publication:
- United States
- Language:
- English
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