- No. 22-01 – Detecting Flow-Induced Vibration in Bellows
The NESC performed testing to determine if high-speed video techniques can be used to predict the onset of flow-induced vibrations (FIV) in bellows. A comprehensive test matrix was established to determine if Motion Magnification (MM) and Digital Image Correlation (DIC) can be used to determine the onset of FIV in straight and gimbaled bellows. Several of the tests were intended to determine if MM and DIC can establish the resonant frequencies of the bellows with no a priori knowledge. The results of the MM and DIC were compared with data from strain gages and microphones. Although the testing was limited to one single-ply unshielded bellows, this effort provided the proof-of-concept that MM and DIC are feasible methods for determining the onset of FIV in bellows. - No. 22-02 – Revisiting Filtration Standards and Definitions for Spaceflight Propulsion and Pressurant Systems
The NESC performed an assessment of existing filtration standards and guidance documents for propellant and pressurant systems. The assessment included a vendor survey to better understand concerns about filtration systems, defined a common set of filtration and contamination-related terms, and developed guidelines for system filtration design and implementation.
All previous NESC technical bulletins are available on the Technical Bulletins page.