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Focused laser differential interferometry post-processing methodology for flowfields with circular symmetry

Ponchio Camillo, Giannino and Wagner, Alexander (2023) Focused laser differential interferometry post-processing methodology for flowfields with circular symmetry. Review of Scientific Instruments, 94 (045102), pp. 1-15. American Institute of Physics (AIP). doi: 10.1063/5.0132874. ISSN 0034-6748.

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Official URL: https://aip.scitation.org/doi/10.1063/5.0132874


An analytic methodology is presented to reconstruct the pressure waveform of flowfields with circular symmetry from the phase shift detected with Focused Laser Differential Interferometry (FLDI). A weak blast wave generated by an electric spark in ambient air is investigated with the proposed approach. Values of separation distance between the differentiating foci of the FLDI dx of 76, 120, 175, and 252*10^(-6) m are employed to probe the flowfield at locations between 3 and 50 mm from the spark source. In a subset of these distances, reference measurements of peak pressure obtained with a surface pressure sensor indicate good agreement with the reconstructed data when small separation distances are used. Further analysis of FLDI reconstructed data is conducted using theoretical correlations for N-waves in terms of the distribution of pressure peak amplitude and compression phase as the wave front propagates. Agreement with theory is verified for all differentiation separation distances except the largest, for which peak pressure comparison shows a 10% loss of measured vs predicted value. A computational FLDI is employed to scrutinize the simplifying hypotheses supporting the waveform reconstruction approach. The direct comparison between experimental and computational FLDI output reveals additional discrepancies for intermediate dx values but very good agreement for the smallest dx. The proposed methodology is thus verified to be reasonable, upon appropriate minimization of the FLDI differentiation distance. A parametric analysis using computational FLDI indicates the adequate value of FLDI dx to be 20% or less of the flowfield characteristic length in terms of density gradient.

Item URL in elib:https://elib.dlr.de/194619/
Document Type:Article
Title:Focused laser differential interferometry post-processing methodology for flowfields with circular symmetry
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Ponchio Camillo, GianninoUNSPECIFIEDhttps://orcid.org/0000-0002-2178-0777UNSPECIFIED
Wagner, AlexanderUNSPECIFIEDhttps://orcid.org/0000-0002-9700-1522UNSPECIFIED
Date:3 April 2023
Journal or Publication Title:Review of Scientific Instruments
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 1-15
EditorsEmailEditor's ORCID iDORCID Put Code
Publisher:American Institute of Physics (AIP)
Keywords:FLDI, HEG, hypersonics, high frequency density fluctuations
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Transportation
DLR - Research area:Raumfahrt
DLR - Program:R RP - Space Transportation
DLR - Research theme (Project):R - Reusable Space Systems and Propulsion Technology
Location: Göttingen
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Spacecraft, GO
Deposited By: Wagner, Alexander
Deposited On:15 Jun 2023 14:17
Last Modified:15 Jun 2023 14:17

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