Exploratory Measurement of Recession Rates of Low Temperature Ablators Subjected to Mach 6 Flow
Abstract
The high speed/high-temperature effect of heat shield ablation was simulated in the low-enthalpy AFRL Mach 6 Ludwieg Tube using solid dry ice as a low-temperature sublimator. The experiments utilized both 21 deg half-angle cones and bi-conic models with a 7 deg half-angle leading edge followed by a 26 deg half-angle base contained within a cryogenic-cooled stainless steel holder. A method of fabricating dry ice test articles was developed using commercially procured dry ice and custom-made aluminum molds. Tests were performed at Mach 6.1 with a stagnation temperature of 490 K and stagnation pressures ranging from 40 - 500 psi. Unit Reynolds number ranged from 2.6 x 106 to 23 x 106 m-1.High-speed Schlieren photography with a frame rate of 20 kHz was used for visualization and data analysis. Nose recession rates were determined by overlaying time-sequenced images and measuring the loss of material at the leading edge. The observed ablation rates compared favorably to previous research and were analyzed using the Fay-Riddell stagnation point heating correlation. While the test program yielded good results, there are several opportunities for improvement. One challenge was maintaining the dry ice model position and shape during the evacuation of the test section. This exploratory effort demonstrated the potential for other uses of dry ice test models in the facility, including for store separation experiments and localized particle-based flow visualization.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 24, 2022
- Accession Number
- AD1175610
Entities
People
- Ross H. Kellet
Organizations
- Air Force Institute of Technology