Imaging and Photophysics
Why are imaging and photophysics important?
Imaging techniques allow for two-dimensional quantitative measurements of thermodynamic parameters in a flow field with a high temporal resolution. Photophysics connects quantitative physical parameters to the light intensities encapsulated in recorded images. Imaging techniques are in situ, non-invasive and are beneficial for measuring flows with non-uniformities and large spatial gradients. Phenomena such as fluid mixing, chemical reaction zones, and wave structures can be captured and quantified. These techniques are useful for understanding the dynamics of gases in real systems, such as scramjets, internal combustion engines, and high-speed flight models.
Schlieren imaging of buoyancy flow and blow out on a match [1]
How does imaging and photophysics work?
Absorption, transmission, and emission processes vary in space and time as functions of the local thermodynamic conditions and composition. Imaging techniques use pixel arrays to collect spatially-resolved light caused by these variations to visualize gradients in gas properties. Through these techniques, the evolution of parameters such as temperature, pressure, velocity, and composition can be determined as functions of space and time.
Reference:
[1] V. Miller, M. Tilghman, R.K. Hanson, “The Hidden Complexities of the Simple Match,” 67th Annual Meeting of the APS Division of Fluid Dynamics, 2014, DOI: 10.1103/APS.DFD.2014.GFM.V0012
