Thermal Performance of 625-kg/m3 Elastomeric Ablative Materials on Spherically Blunted 0.44-Radian Cones.
Abstract
Spherically blunted 0.44-radian (25 deg) half-angle conical models coated with elastomeric ablative materials were tested in supersonic arc-heated wind tunnels to evaluate performance of the ablators over a range of conditions typical of lifting entry. Four test conditions were combinations of stagnation-point heat-transfer rates of 2.3 and 4.5 MW/m2 (200 and 400 Btu/ft2-sec) and stagnation pressures of 20 and 2 kN/m2 (0.2 and 0.02 atm). Afterbody values of heat-transfer rate and pressure were 0.05 to 0.20 of stagnation-point values. Stagnation enthalpy varied from 4.4 to 25 MJ/kg (1900 to 11 000 Btu/lbm) and free-stream Mach number was in a range from 3.5 to 4. Ablative materials retained the spherical nose shape throughout tests at the lower heat-transfer level, but receded, assuming a flattened nose shape, during tests at the high heat-transfer level. The residue layer that formed on the conical afterbody was weak, friable, and extensively cracked. The reference ablative material, which contained phenolic microspheres, generally retained the conical shape on the model afterbody. However, a modified ablator, in which phenolic microspheres were replaced with silica microspheres, deformed and separated from the undegraded material, and thereby produced a very uneven surface. Substrate temperatures and ablator recession were in good agreement with values computed by a numerical analysis, for which one set of material properties and environmental data represented the four test conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1972
- Accession Number
- ADA307326
Entities
People
- Andrew J. Chapman
Organizations
- Langley Research Center