X-33 experimental aeroheating at Mach 6 using phosphor thermography

The goal of the NASA reusable launch vehicle technology program is to matur e and demonstrate essential, cost-effective technologies for next-generatio n launch systems. The X-33 flight vehicle presently being developed by Lock heed Martin is an experimental single-stage-to-orbit demonstrator that seek s to validate critical technologies and ensure applicability to a full-scal e reusable launch vehicle. As with the design of any hypersonic vehicle, th e aeroheating environment is an important issue, and one of the key technol ogies being demonstrated on X-33 is an advanced metallic thermal protection system. As part of the development of this thermal protection system, the X-33 aeroheating environment is being defined through conceptual analysis, ground-based testing, and computational fluid dynamics. An overview of the hypersonic aeroheating wind-tunnel program conducted at the NASA Langley Re search Center in support of the ground-based testing activities is provided . Global surface heat transfer images, surface streamline patterns, and sho ck shapes were measured on 0.013 scale (10-in.) ceramic models of the propo sed X-33 configuration in Mach 6 air. The test parametrics include angles o f attack from -5 to 40 deg, unit Reynolds numbers from I x 10(6) to 8 x 10( 6)/ft, and body-flap deflections of 0, 10, and 20 deg. Experimental and com putational results indicate the presence of shock/shock interactions that p roduced localized heating on the deflected flaps and boundary-layer transit ion on the canted fins. Comparisons of the experimental data to laminar and turbulent predictions were performed. Laminar windward heating data from t he wind tunnel was extrapolated to flight surface temperatures and generall y compared to within 50 degreesF of flight prediction along the centerline. When coupled with the phosphor technique, this rapid extrapolation method would serve as an invaluable thermal protection system design tool.