Summary
Low-cost, large-scale liquid rocket engines with regeneratively cooled nozzles will enable reliable and reduced-cost access to space. Coolant, contained under high pressure, circulates through a bank of channels within the nozzle to properly cool the nozzle walls to withstand high temperatures and prevent failure. It has been a challenge to affordably manufacture and close out the intricate nozzle channels. As such, NASA developed a robust and simplified additive manufacturing technology to build the nozzle liner outer jacket to close out the channels within and contain the high-pressure coolant. The new Laser Wire Direct Closeout (LWDC) capability reduces the time to fabricate the nozzle and allows for real-time inspection during the build. One variation enables a bimetallic part (copper/super-alloy, e.g.) to help optimize material where it is needed. The manufacturing process has been demonstrated on a series of different alloys. Hot-fire testing is complete—the parts were exposed to extreme combustion chamber temperatures and pressure conditions for 1,000+ seconds. Micro-graph examination of the hot-fired test article has verified that the coolant channel closeout bonds are reliable and that there is very little deformation to the coolant channels.