Effects of ablation products on ionization in hypersonic wakes.

Abstract

Recent interest in ionized hypersonic wakes has prompted the present study of the effects of ablation products on wake ionization. Such effects are examined through computations of wake flows composed of carbon, hydrogen, and sodium-containing species added to the air constituents. A 20 species, 31 reactions chemical system is considered. An exact (finitedifference) method for solving the conservation equations for chemically reacting wake flow is employed for both laminar and turbulent flow regions. The ablation product influences investigated are the direct ; ionization of readily ionized additives, the modification to the thermodynamic state resulting from the mixing of additives with the air and the alteration of over-all ionization kinetics through the provision of alternative mechanisms. In order to ascertain these effects separately, four different chemical subsystems of increasing complexity are treated. These are pure air; air plus sodium; air, sodium, and hydrogen; and air, sodium, hydrogen, and carbon monoxide systems. In addition, each chemical system is studied for two sets of initial (neck) conditions for the postneck wake: high- and low-enthalpy cases. Results demonstrate that ablation species exert significant influences on wake ionization and must be properly accounted for in any practical studies of ablating body wakes.