Vibrational Relaxation of Anharmonic Oscillators in Expansion Nozzles
Abstract
The problem of the vibrational relaxation of anharmonic oscillators in expansion nozzles has been analysed numerically. It is concluded: (1) Effects of anharmonicity increase with increasing p_{r}r^{*}/\tanθ and/or T_{r}, where p_{r} and T_{r} are the reservoir pressure and temperature, and r^{*} and θ are the throat radius and expansion angle of the nozzle respectively. (2) Anharmonicity has the effect of somewhat lowering the translational temperature of gas. This effect being taken into account, the relaxation rate of the vibrational energy gets an increase of less than a factor 1.3 due to anharmonicity. Contrary to the Boltzmann distribution of the harmonic oscillators, however, the vibrational distribution function of the anharmonic oscillators undergoes a considerable distortion in the expanding flow.
 Publication:

Journal of the Physical Society of Japan
 Pub Date:
 May 1976
 DOI:
 10.1143/JPSJ.40.1391
 Bibcode:
 1976JPSJ...40.1391N
 Keywords:

 Conservation Equations;
 Gas Dynamics;
 Gas Expansion;
 Molecular Relaxation;
 Nozzle Flow;
 Boltzmann Distribution;
 Equilibrium Flow;
 Harmonic Oscillators;
 Nozzle Geometry;
 Numerical Integration;
 Steady Flow;
 Atomic and Molecular Physics