Abstract
An image fibre Background Oriented Schlieren (Fibre BOS) technique has an advantage in cost-effectiveness as well as portability and flexibility for a time-resolved quantitative three-dimensional unsteady density measurement. The reason why the Fibre BOS technique has these advantages is that a transparent medium can be visualized at several projection angles, which are required for a tomographic reconstruction, using the flexible optical image fibres instead of expensive high-speed cameras, simultaneously. The basic and demonstration experiments were conducted to investigate the performances of the Fibre BOS technique in this study. The estimation accuracy of a deflection angle is increased when a background-dot size is more than twice as large as a core which is the component of the image fibre if the core size is larger than a pixel size on an image sensor. Multiple images going through the image fibres from several projection angles are simultaneously captured using a single camera, and temporal variation of an unsteady complex flow is measurable. The Fibre BOS technique has a potential to conduct the high time-resolved three-dimensional unsteady density measurement using a single high-speed camera.
Graphic abstract
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
Availability of data and material
The images shown in Fig. 8 are available from the corresponding author upon reasonable request.
References
Alter P et al (2007) An introduction to fiber optic imaging, 2nd edn. SCHOTT North America
Atcheson B, Ihrke I, Heidrich W, Tevs A, Bradley D, Magnor M, Seidel HP (2008) Time-resolved 3D capture of non-stationary gas flows. ACM Trans Gr (Proc. SIGGRAPH Asia). https://doi.org/10.1145/1409060.1409085
Daichin LSJ (2003) Evaluation of recursive PIV algorithm with correlation based correction method using various flow images. KSME Int J 17:409–421
Dalziel SB, Hughes GO, Sutherland BR (2000) Whole-field density measurements by ‘synthetic schlieren.’ Exp Fluids 28(4):322–335
Elsinga GE, van Oudheusden BW, Scarano F, Watt DW (2004) Assessment and application of quantitative schlieren methods: calibrated color schlieren and background oriented schlieren. Exp Fluids 36:309–325
Gojani AB, Kamishi B, Obayashi S (2013) Measurement sensitivity and resolution for background oriented schlieren during image recording. J vis 16:201–207
Hart DP (2000a) Super-resolution PIV by recursive local-correlation. J vis 3:187–194
Hart DP (2000b) PIV Error Correction. Exp Fluids 29:13–22
Hecong L, Chongyuan S, Weiwei C (2020) Time-resolved three-dimensional imaging of flame refractive index via endoscopic background-oriented Schlieren tomography using one single camera. Aerosp Sci Technol 97:105621
Hirose Y et al (2019) The quantitative density measurement of unsteady flow around the projectile. J Flow Control Meas vis 7(2):111–119. https://doi.org/10.4236/jfcmv.2019.72009
Kak AC, Slaney M (1988) Principle of computerized tomographic imaging. IEEE Press, New York
Meier GEA (2002) Computerized background-oriented schlieren. Exp Fluids 33:181–187
Mitschke F (2009) Fiber optics: physics and technology. Springer, Verlag Berlin Heidelberg
Nicolas F et al (2016) A direct approach for instantaneous 3D density field reconstruction from Background Oriented Schlieren (BOS) measurements. Exp Fluids 57(1):13
Nicolas F et al (2017a) Experimental study of a co-flowing jet in ONERA’s F2 research wind tunnel by 3D Background Oriented Schlieren. Meas Sci Technol 28(8):085302
Nicolas F, Donjat D, Léon O, Le Besnerais G, Champagnat F, Micheli F (2017b) 3D reconstruction of a compressible flow by synchronized multi-camera BOS. Exp Fluids 58:46
Ota M, Hamada K, Kato H, Maeno K (2011) Computed-tomographic density measurement of supersonic flow field by colored-grid background oriented schlieren (CGBOS) technique. Meas Sci Technol 22:104011
Ota M, Leopold F, Noda R, Maeno K (2015) Improvement in spatial resolution of background-oriented schlieren technique by introducing a telecentric optical system and its application to supersonic flow. Exp Fluids 56(3):1–10
Raffel M (2015) Background-oriented schlieren (BOS) techniques. Exp Fluids 56(3):1–7
Raffel M et al (2018) Particle image velocimetry: a practical guide, 3rd edn. Springer International Publishing
Raffel M, Richard H, Meier GEA (2000) On the applicability of background oriented optical tomography for large scale aerodynamic investigations. Exp Fluids 28:477–481
Ukai T, Russell A, Zare-Behtash H, Kontis K (2018) Temporal variation of the spatial density distribution above a nanosecond pulsed dielectric barrier discharge plasma actuator in quiescent air. Phys Fluids 30:116106
Venkatakrishnan L, Meier GEA (2004) Density measurements using the Background Oriented Schlieren technique. Exp Fluids 37:237–247
Venkatakrishnan L, Suriyanarayanan P (2009) Density field of supersonic separated flow past an afterbody nozzle using tomographic reconstruction of BOS data. Exp Fluids 47:463–473
Westerweel J (2000) Theoretical analysis of the measurement precision in particle image velocimetry. Exp Fluids 29:S003-S012
Acknowledgements
Special thanks are directed towards Mr. Katunari Ota in Osaka Institute of Technology and Mr. Takahito Sakai in TOKAI SANYU TECHNOS Co., Ltd for supporting the experimental setup.
Funding
This work was supported by JSPS KAKENHI Grant Number 20K14655.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflicts of interest
The authors declare that they have no conflict of interest.
Rights and permissions
About this article
Cite this article
Ukai, T. The principle and characteristics of an image fibre Background Oriented Schlieren (Fibre BOS) technique for time-resolved three-dimensional unsteady density measurements. Exp Fluids 62, 170 (2021). https://doi.org/10.1007/s00348-021-03251-2
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/s00348-021-03251-2