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Tessa Fedotowsky

Publications and source records attributed to Tessa Fedotowsky.

7 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2024

Welding of Crack Sensitive Aluminum Alloys for Liquid Rocket Propulsion Applications

In this welding test campaign, electron beam welding (EBW) and manual gas tungsten arc welding (GTAW) processes were utilized to join an additively manufactured aluminum alloy nozzle to a wrought aluminum flange. Both aluminum alloys were 6061, which in their conventional form are susceptible to solidification cracking issues. The AM nozzle utilized a novel high-performance modified version of 6061 which exhibits crack resistant properties during the AM process and during welding. When manually conducting GTAWs a filler wire with the same modified version of 6061 was utilized to weld different combinations of 6061 coupons (either modified or unmodified). Due to the grain refinement technology in the modified 6061, either as filler material or base material, there was complete elimination of weld solidification cracking. During EBW development a combination of wrought 6061 with a modified and additively manufactured 6061 was investigated. The EBWs developed exhibited no crack like defects. Each weld development program utilized non-destructive evaluation, metallography, and mechanical testing to determine the final weld acceptance. Mechanical testing involved hardness evaluation and tension testing on welded coupons. Both welding techniques were successfully developed and exhibited adequate properties for the final test articles and met all requirements of the development campaign. These welds were ultimately developed to be utilized on a set of all-aluminum liquid rocket nozzles to demonstrate additively manufactured aluminum alloys for propulsion applications. These aluminum nozzles were tested at NASA Marshall Space Flight Center’s hot fire test facility and subsequently underwent a test campaign involving a variety of chamber pressures and liquid propellant combinations. Following the hot fire test campaign each weldment was investigated for post operation performance and any defects that may have evolved during testing.

Welding↗
NASA NTRSDate not supplied

Current State of NASA Continuously Rotating Detonation Cycle Engine Development

NASA is currently investigating continuous detonation cycle engines for the application of lander and interplanetary space exploration missions. The performance benefits of a detonation cycle engine may allow for a broader design trade space and more compact geometry required for future missions to the Moon and onwards towards Mars. However, the technology readiness level (TRL) within the US was found to be low with several major risk factors that require understanding prior to full engine system development. One area of uncertainty is the extreme heat loads expected during thermal steady state conditions. To achieve this, an announcement for collaborative opportunity (ACO) partnership between IN Space LLC and NASA Marshall Space Flight Center (MSFC) was established to explore integration of additive manufacturing (AM) processes and the high conductance copper-based alloys, GRCop-42 and GRCop-84. This work outlines the hot fire testing of a 7K lbf thrust class fully AM GRCop-alloy rotating detonation rocket engine (RDRE). Two annular thrust chamber configurations emulating a lander engine system were tested with LOx/GH2 and LOx/LCH4. In both configurations, select hardware was actively cooled using de-ionized water and regeneratively cooled using LCH4. All primary hardware survived long duration tests to thermal steady state up to 133 seconds in a single burn. In total, 18 starts and 802 seconds of duration were achieved with and without visual confirmation of waves present. The proportion of burned propellant, or level of complete combustion, was found to be high compared to the theoretically achievable mean chamber pressure in all cases.

Thomas Teasley↗
NASA NTRSDate not supplied

High Performance Rotating Detonation Rocket Engine for Mars Interplanetary Transport

NASA has successfully evaluated the performances and survivability of two additively manufactured (AM) continuously rotating detonation cycle rocket engine (RDRE) thrust chambers. The AM hardware was subjected to long duration continuous detonative environments in excess of 100 seconds. Performance trends were directly compared to theory and similar scale constant pressure engines with identical propellants. The performance benefits of RDREs include higher combustion efficiency at a more compact design trade space, which allow advantages for future NASA missions. A major finding of this work is that the heat fluxes experienced are substantially higher than traditional liquid rocket engines at the same operating conditions. In addition, completion of combustion occurs rapidly in an annular geometry at ¼ that of the L* and L’ of an equivalent state-of-the-art thrust chamber. Finally, all hardware survived the extreme environments and achieved the major goal of the test project by demonstrating hot fire conditions with detonation modes up to 133 seconds in duration. Follow-on efforts funded by STMD Early Career Initiative (ECI) award are now focused on achieving higher performances than the previous designs and closing the remaining technology risks.

Thomas Teasley↗
NASA NTRSDate not supplied

Al6061-RAM2 Development and Hot-Fire Testing using Additive Manufacturing Laser Powder Directed Energy Deposition for Liquid Rocket Engine Channel-Cooled Nozzles

Aluminum 6061-RAM2 is a high-strength aluminum feedstock developed for additive manufacturing (AM)processes. This alloy leverages Reactive Additive Manufacturing (RAM) technology. The RAM aluminum alloys were developed to be weldable—therefore printable—while equaling or exceeding strength properties of high strength wrought aluminum alloys. NASA and industry partners developed Laser Powder Directed Energy Deposition (LP-DED)additive manufacturing of Al6061-RAM2 for use in aerospace applications. Efforts included establishing build parameters, characterizing the alloy, fabricating components, and completing hot-fire testing of complex internal channel-cooled nozzles. These efforts are to address the growing need for large-scale parts using high-performance light-weight materials. Two rocket engine nozzles were fabricated using LP-DED Al6061-RAM2 that included integral cooling channels. The Al6061-RAM2 has completed process development and initial properties were established. This paper provides an overview of the LP-DED process development, material characterization and properties, component manufacturing, supplemental development, and hot-fire testing. Results from hot-fire testing are provided for a lander-class 31kN (7,000lbf) thrust engine using Liquid Oxygen (LOX)/Liquid Hydrogen (LH2) and LOX/Methane (LCH4).

Al6061-RAM2↗