A technique for simultaneous velocity measurement of liquid and gas phases

Chen, Tzong; Nejad, A. S.; Carter, Cam; Goss, L. P.

doi:10.2514/6.1994-494

Cited by 2 publications

(1 citation statement)

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“…A level-searching routine was developed for tracking the droplet image to yield geometric information such as image area (can be related to droplet size), circumference, and mass center. 8 This additional information greatly enhanced the pairing process of the displaced droplets. Typically, about 13 s are required for the determination of the droplet locations in an image composed of roughly 6000 droplets.…”

Section: System Development Strategies and Proceduresmentioning

confidence: 98%

Multifunction droplet imaging and velocimetry system for spray jets

Chen

Roe

Nejad

1994

Journal of Propulsion and Power

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The development of a multifunction instrumentation system capable of scalar imaging and velocity-vector mapping of a dense liquid jet in crossflow is described. This system requires only one laser that is double-pulsed to produce droplet-displacement images. Direct image digitization and processing using a combination of a charge-coupled device camera, controller, microcomputer, and custom software has shortened the image-processing time from days to minutes. Important features of this effective image-analysis process include 1) a highspeed, general-purpose scheme capable of analyzing image size and shape factor, therefore determining droplet location; 2) a rapid method of computing two-dimensional spatial correlation; 3) a compact data structure for merging image-intensity and geometry information to reduce data storage and improve tracking accuracy; and 4) a newly developed three-point interpolation scheme that preserves the two-dimensional vector field for postprocessing. Application of this imaging system to the study of liquid jets transversely injected into a crossflow has yielded a much improved formulation that takes into account multizone jet behavior in describing jet penetration into the crossflow. The measurement of droplet and spray fragment velocities throughout the spray field indicated substantial droplet-freestream velocity slip even at far-downstream locations.

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Section: System Development Strategies and Proceduresmentioning

confidence: 98%