FEASIBILITY DEMONSTRATION OF A ROCKET ENGINE ABLATION GAUGE.

The program objective is to demonstrate the feasibility of dynamically measuring ablation and erosion of rocket nozzle liner materials and includes analytical studies to establish design parameters, laboratory experiments to evaluate test variables, and five rocket engine tests of the measurement technique. During the Task I phase, the following major efforts were completed 1 Radiochemicals were selected to be used as trace additives in needles used to measure erosion and ablation of rocket liner materials. The additives were 95ZrO2 or 46Sc2O3 as the erosion radiochemicals and 203HgCl2 or 113SnCl2 as the ablation radiochemicals. 2 A system analysis was performed to provide guidance in the system design and source selection. Relationships were derived to determine measurement sensitivity as a function of source gamma energy and needle length. The analysis showed that a source strength of 0.4 to 1.0 millicurie is required for each additive in the needle to provide a 1 count rate accuracy. Adjacent sources were found to contribute less than 1 of the detected count rate and therefore will not cause significant interference. 3 Necessary hardware and fixtures were designed to mount six radiation detectors at the periphery of a 5K engine nozzle. Two detectors can be positioned as close together as 2-78 inches detector centerline measurement, while axial locations can be varied from 12 inch upstream from the nozzle throat to the exit of the nozzle. Author