HYPERSONIC ABLATION
Abstract
Refractory material, such as quartz, upon exposure to high enthalpy environment softens, melts, and flows under the influence of gas-shearing action. A fraction of the melt vaporizes and is introduced into the boundary layer. This behavior is complicated by body forces due to deceleration and to instability at the liquid-air interface. In materials such as Teflon, the intermediate liquid phase is not present and sublimation of the solid occurs directly. This type of material sublimes at a low surface temperature and, through a depolymerization process, a monomer is formed which reacts with the environmental constituents of dissociated air species. At high s rface temperatures the plastics, represented by a phenolic resin reinforced with nylon or by a foamed polyurethane, are proven ablators. A thin layer of plastic is affected by the high heat flux due to its low thermal conductivity. Characteristics of this material are the char layer formed from the depolymerization process within the plastic and the generation of gases represented by methane, hydrogen, etc. Further complication occurs due to the oxidation processes at the surface of the char with the dissociated air species. Refractory material, as graphite, ablates by the oxidation process and is affected by the mass transfer and heterogeneous reactions at i s surface.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1962
- Accession Number
- AD0275292
Entities
People
- H. Lew
- L. Steg
Organizations
- General Electric