Simultaneous schlieren and shadowgraph visualization of fluid flow using one color CCD camera

A Martinez Gonzalez¹, and D Moreno Hernandez^2
1Depto. de Ingeniería Robótica, Universidad Politécnica del Bicentenario,
Carr. Silao – Romita km 2, San Juan de los Duran, C.P. 36283, Silao, Guanajuato, México.
²Centro de Investigaciones en Óptica A.C., Loma del Bosque 115,
Lomas del Campestre, CP 37150, León, Guanajuato, México
This article is dedicated to Professor Cesar Sciammarella

Fluid flow analysis, where its behavior is highly unstable, requires information from different optical methods to validate the observables. Usually, this task is carried out by implementing different optical setups, and the visualization of the flow. However, the complexity of these systems makes their implementation a challenge. Therefore, to facilitate the study of this fluid flow phenomenon with more manageable optical systems, we propose a z-schlieren setup that allows simultaneous recording of horizontal and vertical sensitivity schlieren images and shadowgraph images. The optical system employs two ultra-thin filters, an RGB Light Emitting Diode (LED), and a color digital camera. The performance of the optical system is demonstrated by visualizing different fluid flows. The results of this study show that shadowgraph images are contaminated with the crosstalk effect, and correction against it was applied. The data obtained is significantly improved over the existing standard schlieren methods. © Anita Publications. All rights reserved.
Keywords: Schlieren, Shadowgraph, Ultra-thin filters, Crosstalk.

Peer Review Information
Method: Single- anonymous; Screened for Plagiarism? Yes
Buy this Article in Print © Anita Publications. All rights reserve

References

1. Vogel A, Apitz I, Freidank S, Dijkink R, Sensitive high-resolution white-light Schlieren technique with a large dynamic range for the investigation of ablation dynamics, Opt Lett, 31(2006)1812–1814.
2. Tang J W, Liebner T J, Craven B A, Settles G S, A schlieren optical study of the human cough with and without wearing masks for aerosol infection control, J R Soc Interface, 6(2009)S727–S736.
3. Barnes N F, Bellinger S L, Schlieren and shadowgraph equipment for air flow analysis, J Opt Soc Am, 35(1945) 497–509.
4. Korpel A, Yu T T, Snyder H S, Chen Y M, Diffraction-free nature of Schlieren sound-field images in isotropic media, J Opt Soc Am, 11(1994)2657–2663.
5. Stanic S, Quantitative schlieren visualization, Appl Opt, 17(1978)837–842.
6. Agrawal A K, Butuk N K, Gollahalli S R, Griffin D, Three-dimensional rainbow schlieren tomography of a temperature field in gas flows, Appl Opt, 37(1998)479–485.
7. Wong T, Agrawal A K, Quantitative measurements in an unsteady flame using high-speed rainbow schlieren deflectometry, Meas Sci Technol, 17(2006)1503; doi. 10.1088/0957-0233/17/6/031.
8. Alvarez-Herrera C, Moreno-Hernández D, Barrientos-García B, Guerrero-Viramontes J A, Temperature measurement of air convection using a Schlieren system, Opt Laser Technol, 41(2009)233–240.
9. Martínez-González A, Moreno-Hernández D, León-Rodríguez M, Carrillo-Delgado C, Wide-range average temperature measurements of convective fluid flows by using a schlieren system, Appl Opt, 55(2016)556–564.
10. Prevosto L, Artana G, Mancinelli B, Kelly H, Schlieren technique applied to the arc temperature measurement in a high energy density cutting torch, J Appl Phys, 107(2010)023304; org/10.1063/1.3291099.
11. Agrež V, Požar T, High-speed photography of shock waves with an adaptive illumination, Opt Lett, 45(2020) 1547–1550.
12. Xiao G, Yin J, Chen C, Feng B, Zhong W, Zhang Y, Duan X, Flow visualization and density measurement of the supersonic molecular beam for fusion plasma fueling, Rev Sci Instrum, 92(2021)043539; doi.org/10.1063/5.0039181.
13. Underwood T C, Loebner K T, Miller V A, Cappelli M A, Schlieren diagnostic for cinematic visualization of dense plasma jets at Alfvénic timescales, Exp Fluids, 61(2020)1–13.
14. Zhang P, Xu Z, Wang T, Che Z, A method to measure vapor concentration of droplet evaporation based on background oriented Schlieren, Int J Heat Mass Transfer, 168(2021)120880; doi.org/10.1016/j.ijheatmasstransfer.2020.120880.
15. Tropea C, Yarin A, Foss J, Handbook of experimental fluid mechanics, (Springer, Berlin), 2007.
16. Merzkirch W, Flow visualization, (Academic Press, Orlando), 1987.
17. Settles G S, Schlieren and shadowgraph techniques, (Springer, Berlin), 2001.
18. Barry F W, Edelman G M, An improved schlieren apparatus, J Aeronaut Sci, 15(1948)364; doi.org/10.2514/8.11588.
19. Rudinger G, Somers L M, A Simple Schlieren System for Two Simultaneous Views of a Gas Flow, J SMPTE, 66(1957)622; doi: 10.5594/J17005.
20. Owen R B, Witherow W K, United States Patent #4,391,518 (1983).
21. Golub V V, Kharitonov A I, Sharov I L, Shulmeister A M, in Flow Visualization V: Proceedings of the Fifth International Symposium, R. Reznicek, ed, (Taylor and Francis), 1990, p 556.
22. Chaloupka J L, Wood M, Aas J, Hutchins J, Thistle J D, Color schlieren imaging with a two-path, double knife edge system, Opt Express, 22(2014)8041–8046.
23. Settles G S, A direction-indicating color schlieren system, AIAA J, 8(1970)2282; doi.org/10.2514/3.6106.
24. Stricker J, Zakharin B, Hornick B T, Rosenblatt F, Bidirectional quantitative color schlieren, Opt Eng, 45(2006)123604; doi.org/10.1117/1.2402103.
25. Elsinga G E, Oudheusden B W Van, Scarano F, Assessment and application of quantitative schlieren methods: Calibrated color schlieren and background oriented schlieren, Exp Fluids, 36(2004) 309–325.
26. Kleine H, Grönig H, Takayama K, Simultaneous Shadow, Schlieren and Interferometric Visualization of Compressible Flows, Opt Lasers Eng, 44(2006)170–189.
27. Martinez-Gonzalez A, Moreno-Hernandez D, Horizontally and vertically sensitive schlieren and shadowgraph system, Opt Lett, 47(2022)3596–3599.
28. Caspi D, Kiryati N, Shamir J, Range imaging with adaptive color structured light, IEEE Transactions on Pattern Anal and Mach Intell, 20(1998)470–480.
29. Edmund Optics: longpass and shortpass optical filters: https://www.edmundoptics.com/f/everix-ultra-thin-shortpass-filters/39542/
30. Lumenera corporation: Lt225 Datasheet, available from: https://www.lumenera.com/lt225.html