Condensation of sulfur hexafluoride in steady supersonic nozzle flow

Abstract

Condensation of SF6 carried in argon by homogeneous nucleation has been studied experimentally in two continuously operating supersonic wind tunnels. Condensation onset was detected by Rayleigh light scattering. Calibration of the nozzles by static pressure measurements, together with a solution of equations of motion allowing for the caloric nonideality of the vapor, permitted the determination of the thermodynamic state at the observed onset of condensation. The experiments covered conditions of condensation onset in a range 77<T<113 K, and 0.09<pSF6<4.6 torr, well below the triple point of SF6. The adiabatic supercooling ranged from 38 to 45 C and the results agree qualitatively with the classical theory of homogeneous nucleation.