Abstract
A quantitative rainbow schlieren study was conducted on an over-expanded jet at nozzle pressure ratio of 2.8, based on two different schlieren set-ups: the standard z-type and a single-mirror schlieren set-up. The technique used a single, weak focal-length lens placed in the field of view of the system to provide the calibration information required for the extraction of the quantitative data. In the case of the single-mirror set-up, the calibration image required further post-processing procedures to take into account the double refraction experienced by the light. Density gradients were calculated using Abel transform and compared to validated reference data. Results indicate that the single-mirror set-up is able to improve prediction of the density gradient field as compared to the standard z-type schlieren, due to its inherent property of higher sensitivity. The study has shown that the single-mirror set-up performs on average better than the standard z-type system, yielding an overall averaged error of ± 20%, with localized values as low as ± 5% where the shock cell structure is clearly defined, with respect to the validated reference data. At the same time, both systems perform poorly in regions where the flow structure displays poor image contrast.
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References
Agrawal AK, Butuk NK, Gollahalli SR, DeVon G (1998) Three-dimensional rainbow schlieren tomography of a temperature field in gas flows. Appl Opt 37(3):479–485
Agrawal AK, Alammar KN, Gollahalli SR (2002) Application of rainbow schlieren deflectometry to measure temperature and oxygen concentration in laminar gasjet diffusion flame. Exp Fluids 32:479–485
Al-Ammar K, Agrawal AK, Gollahalli SR, DeVon G (1998) Application of rainbow schlieren deflectometry for concentration measurements in an axisymmetric helium jet. Exp Fluids 25:89–95
Al-Ammar K, Agrawal AK, Gollahalli SR (2000) Quantitative measurements of laminar hydrogen gas-jet diffusion flames in a 2.2 s drop tower. Proc Combust Inst 28:1997–2004
Albers BW, Agrawal AK (1999) Schlieren analysis of an oscillating gas-jet diffusion flame. Combust Flame 119:84–94
Desse J-M (2006) Recent contribution in color interferometry and applications to high-speed flows. Opt Lasers Eng 44:304–320
Desse J-M, Oclhewsky F (2017) Digital holographic interferometry for analysing high-density gradients in fluid mechanics. In: Nayadenova I (Ed), Holographic materials and optical systems, Intech Open Access, (Ch 13)
Elsinga GE, 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
Greenberg PS (1995) Quantitative rainbow schlieren deflectometry. Appl Opt 34(19):3810–3822
Hargather MJ, Settles G (2012) A comparison of three quantitative schlieren techniques. Opt Lasers Eng 50:8–17
Kasyap SP, Agrawal AK (2003) Schlieren measurements and analysis of concentration field in self-excited helium jets. Phys Fluids 15:12
Killer C (2020) Abel inversion algorithm. MATLAB Central File Exchange. https://www.mathworks.com/matlabcentral/fileexchange/43639-abel-inversion-algorithm. Accessed 19 Mar 2020
Kolhe PS, Agrawal AK (2009) Density measurements in a supersonic microjet using miniature rainbow schlieren deflectometry. AIAA J 47(4):830–838
Leopold F (2007) The application of the color background oriented schlieren technique (CBOS) to the free-flight and in-flight measurements. In: Proceedings of the 22nd international congress on instrumentation in aerospace simulation facilities, 10–14 June
Mariani R, Lim HD, Zang B, Vevek US, New TH, Cui YD (2019) A comparative study on the use of calibrated and rainbow schlieren techniques in axisymmetric supersonic jets. Flow Meas Instrum 66:218–228
Mier FA, Hargather MJ (2016) Color gradient background-oriented schlieren imaging. Exp Fluids 57:95
Panigrahi PK, Muralidhar K (2012) Schlieren and shadowgraph methods in heat and mass transfer. Springer eBooks ISBN 978-1-4614-4535-7
Pretzler G (1991) A new method for numerical Abel-inversion. Zeitung fur Naturforschung 46a:639–641
Satti RJ, Kohle PS, Olcmen S, Agrawal AK (2007) Miniature rainbow schlieren deflectometry system for quantitative measurements in microjets and flames. Appl Opt 47(15):2954–2962
Settles GS (2001) Schlieren and shadowgraph techniques: visualizing phenomena in transparent media. Springer, Berlin
Stevenson D, Skews B (2014) Quantitative colour schlieren development. J Vis 18:311–320
Wu J, New TH (2017) An investigation on supersonic bevelled nozzle jets. Aerosp Sci Technol 63:278–293
Zang B, Vevek US, Lim HD, Wei X, New TH (2018) An assessment of OpenFOAM solver on RANS simulations of round supersonic free jets. J Comput Sci 28:18–31
Acknowledgements
The authors gratefully acknowledge support for the study through a Singapore Ministry of Education AcRF Tier-2 grant (Grant number: MOE2014-T2-1-002), support for the second and third authors through NTU Nanyang President Graduate Scholarship and MAE Graduate Research Officer scheme respectively, as well as facility support from Temasek Laboratories at the National University of Singapore.
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Mariani, R., Lim, H.D., Zang, B. et al. On the application of non-standard rainbow schlieren technique upon supersonic jets. J Vis 23, 383–393 (2020). https://doi.org/10.1007/s12650-020-00637-y
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DOI: https://doi.org/10.1007/s12650-020-00637-y