Frozen Sonic Flow Method Applied to Arc-Heated Facilities for Planetary Re-Entry Simulation

Abstract

The most important parameter in low-density arc-heated flows for atmosphere entry simulations is the centerline total enthalpy Hcl which is strictly related to the average total enthalpy Hne (bulk enthalpy at nozzle exit). In this paper the “sonic flow method” widely used for Hcl calculation in mono-atomic and diatomic molecules gas mixtures, has been extended to polyatomic molecules gas mixtures. By means of a reduced-scale arc-jet facility and using Nitrogen N2 as hot feeding gas, three mixtures were investigated by adding cold gases like O2, CO2 and CH4 through a mixer just before the nozzle. Using bulk enthalpies ranging between 5 and 30 [M J/kg] the calculated enthalpy ratios were Hcl/Hne = 1.38 for N2 - O2 mixture, Hcl/Hne = 1.18 for N2 - CO2 mixture and Hcl/Hne = 1.85 for N2 - CH4 mixture.