Quantitative imaging of turbulent and reacting flows
- Sandia National Laboratories, Livermore, CA (United States)
Quantitative digital imaging, using planar laser light scattering techniques is being developed for the analysis of turbulent and reacting flows. Quantitative image data, implying both a direct relation to flowfield variables as well as sufficient signal and spatial dynamic range, can be readily processed to yield two-dimensional distributions of flowfield scalars and in turn two-dimensional images of gradients and turbulence scales. Much of the development of imaging techniques to date has concentrated on understanding the requisite molecular spectroscopy and collision dynamics to be able to determine how flowfield variable information is encoded into the measured signal. From this standpoint the image is seen as a collection of single point measurements. The present effort aims at realizing necessary improvements in signal and spatial dynamic range, signal-to-noise ratio and spatial resolution in the imaging system as well as developing excitation/detection strategies which provide for a quantitative measure of particular flowfield scalars. The standard camera used for the study is an intensified CCD array operated in a conventional video format. The design of the system was based on detailed modeling of signal and image transfer properties of fast UV imaging lenses, image intensifiers and CCD detector arrays. While this system is suitable for direct scalar imaging, derived quantities (e.g. temperature or velocity images) require an exceptionally wide dynamic range imaging detector. To apply these diagnostics to reacting flows also requires a very fast shuttered camera. The authors have developed and successfully tested a new type of gated low-light level detector. This system relies on fast switching of proximity focused image-diode which is direct fiber-optic coupled to a cooled CCD array. Tests on this new detector show significant improvements in detection limit, dynamic range and spatial resolution as compared to microchannel plate intensified arrays.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- OSTI ID:
- 139917
- Report Number(s):
- BNL-48923; CONF-9306172-; ON: DE93015758; TRN: 93:002191-0071
- Resource Relation:
- Conference: 15. combustion research contractors` meeting, Lake Harmony, PA (United States), 2-4 Jun 1993; Other Information: PBD: 1993; Related Information: Is Part Of Fifteenth combustion research conference; PB: 391 p.
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
02 PETROLEUM
HYDROXYL RADICALS
FLUORESCENCE SPECTROSCOPY
NITRIC OXIDE
COMBUSTION
LIGHT SCATTERING
TURBULENCE
DYNAMICS
SPATIAL RESOLUTION
IMAGE INTENSIFIERS
SIGNAL-TO-NOISE RATIO
CHARGE-COUPLED DEVICES
COLLISIONS
QUENCHING
DESIGN
CAMERAS