Performance Enhancement of the Space Shuttle RSRM Nozzle-to-Case Joint Using a Carbon Rope Barrier

A carbon rope "thermal barrier" is being considered as a component to enhance performance of the Reusable Solid Rocket Motor (RSRM) nozzle-to-case joint. Fundamental performance characteristics of the rope have been considered in this paper. In particular, resistance to erosion, ability to filter particulate matter, thermal capacitance, and flow resistance have been considered. Testing results have shown the rope to be resistant to the corrosive internal environment of the RSRM. The rope has also been shown to be an effective "slag barrier." A desirable feature of the rope would be the ability to act as a heat sink. However, analyses have indicated that the thermal capacitance of the rope is not large enough to reduce the temperature of an impinging gas stream below the ablation temperature of the 0-ring for significant time periods, The real value of the rope is its ability to act as a flow diffuser. Flow resistance test, were performed on the rope In the course of testing the rope between parallel plates, an undesirable "blow-by" phenomenon was observed when the compressive stress in the rope was smaller than the upstream gas pressure. It was found, however, that in the converging passage of the actual design, the rope would consistently "Self-seat" and thereby prevent blow-by, even in the absence of any precompression. Flow resistance values have been quantified for use in future analyses. The work presented here provides an initial thermal-fluid assessment of the rope for this application, and lays the groundwork for future development.