Accession Number:



Droplet Size and Evaporation Rate within a Two-Phase Flow by Morphology-Dependent Resonances in the Optical Spectra.

Descriptive Note:

Final rept. 15 Nov 81-31 Dec 84,

Corporate Author:


Personal Author(s):

Report Date:


Pagination or Media Count:



In two-phase chemically reacting flows, the size, shape, and chemical content of fuel droplets affect combustion and their chemical by-products. A new in-situ and nonintrusive optical technique has been developed which provides highly accurate one part in 10000 - 100,000 size and shape determination, as well as provide chemical speciation of the majority species forming the droplet. This all-optical technique uses the morphology-dependent resonances MDRs of spheres, spheroids, or any shape that enables an internal wave to travel around a great circle with appropriate phase shift. These MDRs in the fluorescence spectra of dye-doped droplets flowing in a linear stream have also provided information on 1 evaporation rate of interacting droplets flowing in the ambient or heated environment 2 condensation rate of interacting droplets flowing in a saturated vapor and 3 surface tension and bulk viscosity of individual droplets which have been perturbed by a laser beam so as to cause slight shape distortions, e.g., from spheres to oblate or prolate spheroids. MDRs can provide wavelength selective high Q optical feedback for the internally generated fluorescent and Raman radiation. By using this high optical feedback, lasing from individual dye-tagged droplets of approx. 20 micron radius has been achieved. The potential of using bright lasing droplets as markers in flow diagnostics is promising. Stimulated Raman scattering from individual droplets of approx. 20 micron radius has been achieved. Keywords Liquid droplets LorenzMie formalism Dynamic surface tension Morphology-dependent resonances.

Subject Categories:

  • Fluid Mechanics
  • Optics
  • Combustion and Ignition
  • Fuels

Distribution Statement: