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Robust Cryogenic Compatible Turbo-machinery and Liquid Rocket Engine coatings


OBJECTIVE: Demonstrate feasibility of proposed coating technologies in cryogenic liquid rocket engine environments. DESCRIPTION: In order to enable greater launch capability at significantly reduced operating cost, the Air Force is developing domestic technology for highly reusable oxygen-rich staged combustion hydrocarbon engines. These engines present unique operating challenges, particularly in their turbomachinery. The turbomachinery is highly mechanically loaded while exposed to 8000 psi, 1400 R and oxygen-rich gasses. While monolithic materials have been developed for this application, to date, they have only been partially successful and are extremely expensive. An alternative approach would be to develop a robust coating technology which is able to survive the environment for the 50 launch cycles between overhauls desired for a next generation launch system engine. Novel approaches are desired to develop robust coatings for use in the high temperature, high pressure, oxygen-rich environment of proposed upcoming oxygen-rich staged combustion liquid rocket engines. While coatings have been investigated previously, for example on the Air Force Research Laboratory (AFRL) Integrated Powerhead Demonstration Program, they do not meet the long-life requirements necessary for this type of reusable system. Similarly, while coatings have been successfully applied to aircraft components, those materials have not yet been successfully demonstrated in the more demanding rocket engine environments. Critical issues that must be addressed include: Ability to withstand the requisite environment, including not only chemical and thermal but also the high and low cycle fatigue necessary to achieve a 50 mission life between overhauls; compatibility with and bonding to the substrate material(s); and manufacturability. If applicable, processes for removing the material for part refurbishment, repair of lightly damaged coatings, and methods for non-destructively assessing the condition of the coating can also be addressed. Since the cost of testing in the requisite environment is prohibitive under a SBIR program, it is expected that some demonstrations of the feasibility of the materials, particularly in Phase I, will be achieved through a combination of sub-scale hardware, analysis, similarity, or other approaches. While this is acceptable, clear linkage between the proposed demonstrations and the desired properties is necessary, and will be a critical point of evaluation. As much as possible, direct demonstrations in the relevant environment are encouraged. PHASE I: Demonstrate the feasibility of the proposed material/coating system to survive in an environment representative of a reusable oxygen-rich staged combustion engine turbine. Demonstrations may include analysis or similarity, however clear linkage between any demonstration and the representative environment is critical. PHASE II: Demonstrate and mature the proposed material by manufacture of a representative test article to demonstrate manufacturability and test the article to show survival in the oxygen-rich staged combustion environment. PHASE III: The coatings will be most applicable to the newest generations of turbopumps and other rotating equipment in rockets as well as liquid rocket engines. REFERENCES: 1. G.P. Sutton and O. Biblarz, Rocket Propulsion Elements, 7th Ed., John Wiley & Sons, Inc., New York, 2001, ISBN 0-471-32642-9. 2. D.K. Huzel and D.H. Huang, Modern Engineering for Design of Liquid-Propellant Rocket Engines, Vol. 147, Progress in Astronautics and Aeronautics, Published by AIAA, Washington DC., 1992, ISBN 1-56347-013-6. 3. Yang, V et. al, Liquid Rocket Thrust Chambers: Aspects of Modeling, Analysis, and Design, Vol. 200, Progress in Astronautics and Aeronautics, Published by AIAA, Washington DC, 2004, ISBN 1-56347-223-6.
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