Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Water immersion single-mirror schlieren imaging system for flow visualization

Shubham Saxena, Manish Kumar

Abstract

Schlieren imaging is a popular optical technique for visualizing flow in transparent media. In-water high-sensitivity flow visualization, using schlieren imaging, is usually performed with a large-footprint two-mirror z-configuration. Here, we present a small footprint, easy-to-implement, single-mirror schlieren imaging system for in-water flow visualization. The same system is capable of high-sensitivity flow visualization in air as well. At its core, our system uses a concave mirror with water immersion. We present theoretical analysis and experimental results to show that this water immersion helps reduce the system's footprint by 25%. Our water immersion-based single-mirror schlieren imaging method additionally reduces mirror surface artifacts, increasing the sensitivity of flow visualization. This technique enables a low-cost schlieren system, as demonstrated experimentally using an inexpensive concave mirror. We also provide the experimental validation of high sensitivity in-water flow visualization for some transparent chemicals or solutions.

Water immersion single-mirror schlieren imaging system for flow visualization

Abstract

Schlieren imaging is a popular optical technique for visualizing flow in transparent media. In-water high-sensitivity flow visualization, using schlieren imaging, is usually performed with a large-footprint two-mirror z-configuration. Here, we present a small footprint, easy-to-implement, single-mirror schlieren imaging system for in-water flow visualization. The same system is capable of high-sensitivity flow visualization in air as well. At its core, our system uses a concave mirror with water immersion. We present theoretical analysis and experimental results to show that this water immersion helps reduce the system's footprint by 25%. Our water immersion-based single-mirror schlieren imaging method additionally reduces mirror surface artifacts, increasing the sensitivity of flow visualization. This technique enables a low-cost schlieren system, as demonstrated experimentally using an inexpensive concave mirror. We also provide the experimental validation of high sensitivity in-water flow visualization for some transparent chemicals or solutions.
Paper Structure (9 sections, 18 equations, 7 figures, 1 table)

This paper contains 9 sections, 18 equations, 7 figures, 1 table.

Table of Contents

  1. Introduction
  2. Theory
  3. Schlieren system footprint reduction
  4. Mirror surface artifacts reduction
  5. Experimental results
  6. System footprint reduction
  7. Mirror surface artifacts reduction
  8. In-water flow visualization
  9. Discussion and conclusion

Figures (7)

  • Figure 1: Comparison between two schlieren configurations: a) two-mirrors based z-configuration and b) single-mirror configuration.
  • Figure 2: Effect of a thin liquid lens on the radius of curvature of a concave lens. a) Sag of a concave mirror, b) radius of curvature of a concave mirror, and c) effective radius of curvature of a concave mirror filled with water. The water-lens is a plano-convex lens with the convex side having same but opposite radius of curvature as the mirror.
  • Figure 3: Effect of a thick liquid lens on the radius of curvature of a concave lens. Concave mirror without water lens (left) and concave mirror with a thick water lens (right).
  • Figure 4: Effect of liquid immersion on surface artifact reduction. a) A simplified dent in a mirror surface having depth $L$, and b) liquid (water) immersion of the dented mirror.
  • Figure 5: System footprint reduction with water-lens assisted schlieren. a) Schematics of the single mirror water-lens assisted schlieren setup. b) Actual setup in the lab. c) The tripod height adjustments for schlieren imaging before (main image) and after (inset image) water-immersion of the lens. d) Confirmation of the schlieren contrast with visualization of the butane gas ejecting from a lighter.
  • ...and 2 more figures