Rotational relaxation of H2 in nozzle flow
Abstract
The study seeks to measure the rotational relaxation rate of molecular hydrogen by monitoring the number density of n-H2 in the state where v = 0 and J = 1 in the supersonic nozzle flow. This is done using coherent anti-Stokes Raman spectroscopy (CARS). The CARS transformation coefficient is measured over wide temperature and pressure ranges. The gas mixture (20% H2 + 80% Ar) is heated by a reflected shock wave in a temperature range 2200-2650 K and a pressure range 1.5-5 atm. It is then expanded rapidly through the conical nozzle so that the nonequilibirium conditions between the rotational and the translational degrees of freedom are realized. Here, the concentration of H2 (J = 1) is determined by a CARS technique. The experimental results are analyzed by means of the conventional conservation equations of fluid mechanics and the master equations, with use made of the rate constants with an exponential energy gap law.
- Publication:
-
Shock Tubes and Waves
- Pub Date:
- 1982
- Bibcode:
- 1982stw..proc..552M
- Keywords:
-
- Hydrogen;
- Molecular Relaxation;
- Molecular Rotation;
- Nozzle Flow;
- Argon;
- Conical Nozzles;
- Maxwell-Boltzmann Density Function;
- Raman Spectroscopy;
- Shock Waves;
- Supersonic Flow;
- Fluid Mechanics and Heat Transfer