High Temperature Nozzle Seals for Dissimilar Materials

High-performance, lightweight nozzles and combustion chambers are a core technology need for upper-stage and planetary descent/ascent rocket engines. Future NASA missions to Moon and Mars require reduced weight in combustion chambers and nozzles so that overall mission payload fraction and cost can be improved. Ceramic Matrix Composite (CMC) nozzle extensions are a way to reduce weight and improve specific impulse because of the low density and high temperature capability of the material. CMC nozzles can help reduce component mass to 60% of current values.nbsp;This proposal addresses one of the primary outstanding challenges in using CMC nozzle extensions for flight applications: sealing the interface between metal thrust chamber and CMC nozzle extension. In traditional, heavy engines, the junction between thrust chamber and nozzle extension is welded, but this is impossible for dissimilar materials. In the Phase I effort, PSI will develop a sealing geometry based on existing couplings and incorporating similar joint methodologies from other industries. The performance of the seal will be tested at the nozzle proof pressure, tested at firing temperature, and before and after simulated launch loads have been applied.nbsp;PSI will design and manufacture surrogate nozzles to faithfully represent the nozzle geometry and the coupling. The nozzle surrogates will be machined, assembled, and tested at PSI during Phase I. PSI will deliver a manufacturing sample prototype and design data to NASA at the end of the Phase I effort, and a functional CMC nozzle extension with lightweight coupling at the end of a Phase II effort.