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1. A Review on Schlieren Flow Visualization Technique Maryam Kordbacheh Undergraduate Student Supervisor: Dr. Esfehanian 8/4/1389 Faculty of Mechanical Engineering University of Tehran

3. Technical Considerations

4. Specialized Schlieren Technique

5. Comparison to Other Methods

7. Flow Visualization Methods Compressible flows Smoke visualization Particle Shadowgraphs and Schlieren Incompressible flows Dye Shadowgraphs and Schlieren Particles Bubbles Fluorescence, phosphorescence Drop falling on liquid surface

8. Incompressible Flows Insects walking on water Normal laminar flow chain dye visualization

9. Compressible Flows Shadowgraph Schlieren flow visualization laminar smoke jet

12. the refractive index : n = c0/c

13. For air - index has a linear relation with density: The higher the density, the slower the light moves

14. So, any compressible flow will cause the wave front of light to “turn”.

16. Density gradient causes displacement of source image Displaced Image Image

19. The extra dimension of color helps to have vector directions in addition to scalars

21. 2nd derivative of density

22. Simplest method

23. Lower contrast

24. Schlieren

25. 1st derivative of density

26. Small increase in complexity

27. Increase in contrast

28. Interferometer

29. 2D quantitative measurement of n, T, Density

30. Sum of path differences < λ/10th

32. Schlieren Technique in Application Schlieren for Flight Test

33. Thanks for your Attention