An Experimental Study of the Rotational Distribution Function of Nitrogen in a Shock Wave

摘要

The electron beam fluorescence technique was used to measure the rotational energy distribution through shock waves in nitrogen. At Mach 1.7 the deviation from thermodynamic equilibrium was found to be small and the rotational temperature profile followed the density profile. Comparison with theoretical calcullations yielded the rotational relaxation collision number Z sub R = 5, in reasonable agreement with other determinations. At high Mach numbers the measured rotational distribution function within the shock wave could not be represented by a single temperature, but was found to be representable approximately by the merging of two rotational distribution functions corresponding to temperatures upstream and downstream of the shock wave. The profile of the average local 'temperature' defined by the ratio of the total measured rotational energy to the gas density, was found to precede the density profile through the shock wave by an amount which increased with Mach number. (Author)