Download or read book Integrated High Payoff Rocket Propulsion Technology Ihprpt Sic Recession Model written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: SiC stability and recession rates were modeled in hydrogen/oxygen combustion environments for the Integrated High Payoff Rocket Propulsion Technology (IHPRPT) program. The IHPRPT program is a government and industry program to improve U.S. rocket propulsion systems. Within this program SiC-based ceramic matrix composites are being considered for transpiration cooled injector faceplates or rocket engine thrust chamber liners. Material testing under conditions representative of these environments was conducted at the NASA Glenn Research Center, Cell 22. For the study described herein, SiC degradation was modeled under these Cell 22 test conditions for comparison to actual test results: molar mixture ratio, MR (O2:H2) = 6, material temperatures to 1700 C, combustion gas pressures between 0.34 and 2.10 atm, and gas velocities between 8,000 and 12,000 fps. Recession was calculated assuming rates were controlled by volatility of thermally grown silica limited by gas boundary layer transport. Assumptions for use of this model were explored, including the presence of silica on the SiC surface, laminar gas boundary layer limited volatility, and accuracy of thermochemical data for volatile Si-O-H species. Recession rates were calculated as a function of temperature. It was found that at 1700 C, the highest temperature considered, the calculated recession rates were negligible, about 200 m/h, relative to the expected lifetime of the material. Results compared favorably to testing observations. Other mechanisms contributing to SiC recession are briefly described including consumption of underlying carbon and pitting. A simple expression for liquid flow on the material surface was developed from a one-dimensional treatment of the Navier-Stokes Equation. This relationship is useful to determine under which conditions glassy coatings or thermally grown silica would flow on the material surface, removing protective layers by shear forces. The velocity of liquid flow was found to de

Download or read book Materials Needs and R D Strategy for Future Military Aerospace Propulsion Systems written by National Research Council and published by National Academies Press. This book was released on 2011-07-20 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ongoing development of military aerospace platforms requires continuous technology advances in order to provide the nation's war fighters with the desired advantage. Significant advances in the performance and efficiency of jet and rocket propulsion systems are strongly dependent on the development of lighter more durable high-temperature materials. Materials development has been significantly reduced in the United States since the early 1990s, when the Department of Defense (DOD), the military services, and industry had very active materials development activities to underpin the development of new propulsion systems. This resulted in significant improvements in all engine characteristics and established the United States in global propulsion technology. Many of the significant advances in aircraft and rocket propulsion have been enabled by improved materials and, materials manufacturing processes. To improve efficiency further, engine weight must be reduced while preserving thrust. Materials Needs and Research and Development Strategy for Future Military Aerospace Propulsion Systems examines whether current and planned U.S. efforts are sufficient to meet U.S. military needs while keeping the U.S. on the leading edge of propulsion technology. This report considers mechanisms for the timely insertion of materials in propulsion systems and how these mechanisms might be improved, and describes the general elements of research and development strategies to develop materials for future military aerospace propulsion systems. The conclusions and recommendations asserted in this report will enhance the efficiency, level of effort, and impact of DOD materials development activities.

Download or read book A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs written by National Research Council and published by National Academies Press. This book was released on 2007-01-14 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rocket and air-breathing propulsion systems are the foundation on which planning for future aerospace systems rests. A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs assesses the existing technical base in these areas and examines the future Air Force capabilities the base will be expected to support. This report also defines gaps and recommends where future warfighter capabilities not yet fully defined could be met by current science and technology development plans.