Novel Materials for In-Situ Ablation Sensing

ABSTRACT: In order to achieve precise guidance, navigation and control in re-entry vehicles, aerodynamic shape must be accurately known throughout the flight trajectory. For this Phase I program an ultrasonic-based technique for real-time, non-intrusive (5 KHz) measurement of recession during ablation will be developed. The system combines the elements of ultrasonic thickness gauging technology with ultrasonic thermometry techniques. Novel, independent temperature measurement methods and analysis techniques will be formulated to separate variations attributed to thickness changes from those attributed to temperature changes. Recession, or wall thickness, changes can be measured using sensors located remotely from the ablating surface without modifying the thermal protective system in any way. The measurement concept will be verified through a series of ablation tests where real-time recession data will be quantitatively compared to post-ablation analysis. The instrumentation has low power consumption and can be made sufficiently compact for potential in-flight measurement. BENEFIT: Quantitative real-time recession sensing has application in TPS evaluation for both ground-based testing and in-flight systems. Military markets include NASA, Air Force, Navy and Army. In addition to hypersonics applications, there are also potential applications in combustion research, directed energy research and health monitoring.