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Application of Prandtl's theory in the design of an experimental chamber for static pressure measurements
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SYSNO ASEP 0547472 Document Type J - Journal Article R&D Document Type Journal Article Subsidiary J Článek ve WOS Title Application of Prandtl's theory in the design of an experimental chamber for static pressure measurements Author(s) Šabacká, Pavla (UPT-D)
Neděla, Vilém (UPT-D) RID, ORCID, SAI
Maxa, Jiří (UPT-D)
Bayer, R. (CZ)Number of authors 4 Article number 6849 Source Title Sensors. - : MDPI
Roč. 21, č. 20 (2021)Number of pages 13 s. Publication form Online - E Language eng - English Country CH - Switzerland Keywords ESEM ; BD sensor ; static probe ; static pressure ; mach number ; differentially pumped chamber ; Prandtl’s theory Subject RIV JA - Electronics ; Optoelectronics, Electrical Engineering OECD category Thermodynamics R&D Projects GA19-03909S GA ČR - Czech Science Foundation (CSF) Method of publishing Open access Institutional support UPT-D - RVO:68081731 UT WOS 000714802000001 EID SCOPUS 85117003015 DOI 10.3390/s21206849 Annotation Pumping in vacuum chambers is part of the field of environmental electron microscopy. These chambers are separated from each other by a small-diameter aperture that creates a critical flow in the supersonic flow regime. The distribution of pressure and shock waves in the path of the primary electron beam passing through the differentially pumped chamber has a large influence on the quality of the resulting microscope image. As part of this research, an experimental chamber was constructed to map supersonic flow at low pressures. The shape of this chamber was designed using mathematical–physical analyses, which served not only as a basis for the design of its geometry, but especially for the correct choice of absolute and differential pressure sensors with respect to the cryogenic temperature generated in the supersonic flow. The mathematical and physical analyses presented here map the nature of the supersonic flow with large gradients of state variables at low pressures at the continuum mechanics boundary near the region of free molecule motion in which the Environmental Electron Microscope and its differentially pumped chamber operate, which has a significant impact on the resulting sharpness of the final image obtained by the microscope. The results of this work map the flow in and behind the Laval nozzle in the experimental chamber and are the initial basis that enabled the optimization of the design of the chamber based on Prandtl’s theory for the possibility of fitting it with pressure probes in such a way that they can map the flow in and behind the Laval nozzle. Workplace Institute of Scientific Instruments Contact Martina Šillerová, sillerova@ISIBrno.Cz, Tel.: 541 514 178 Year of Publishing 2022 Electronic address https://www.mdpi.com/1424-8220/21/20/6849
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