Light extinction tomography for measurement of ice crystals and other small particles
Inventors
Bencic, Timothy J. • Rohler, David P. • Fagan, Amy F. • Izen, Steven H. • Maniyedath, Arjun K.
Assignees
United States, Government Administrator Of Nasa • PLEXAR ASSOCIATES Inc
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-10073023-B2
Publication Date
2018-09-11
Expiration Date
Abstract
A tomography duct for wind tunnels includes a plurality of light sources and sensors displaced around a support structure. The light sources are cycled and sensor measurements are made from sensors opposite the light sources. Tomographic algorithms are used to determine an extinction map from the sensor measurements. The extinction map provides details about particles in a cross-section of the air flow through the tomography duct.
Core Innovation
The invention provides a system with a support frame at least partially surrounding a cavity through which a flow of air passes. A plurality of electromagnetic emitters displaced along the support frame emit electromagnetic radiation into the cavity to illuminate at least a cross-section of the flow of air, and a plurality of electromagnetic detectors displaced along the support frame detect the electromagnetic radiation emitted toward the cavity.
A controller cycles on-and-off each electromagnetic emitter in an illumination pattern, acquires measurements from selected detectors during each on-cycle, and reconstructs an extinction map of the cross-section using a tomography algorithm. The extinction map is used to determine one or more characteristics of particles in the flow of air from a plurality of acquired measurements generated during the emitter on-cycles.
Tomography reconstruction includes iterative reconstruction, filtered backprojection, truncated singular value decomposition, and diffraction tomographic reconstruction. In this context, extinction maps correspond to particle density and/or water content of particles such as ice crystals, supercooled water, and water droplets, enabling particle characterization from the reconstructed extinction distribution.
Claims Coverage
The independent claim set includes one independent claim, with additional refinement provided by dependent claims. The core inventive coverage centers on cycling electromagnetic emitters in an illumination pattern, acquiring detector measurements during each emitter on-cycle, reconstructing an extinction map via tomography, and determining particle characteristics from that extinction map, with dependent claims specifying particular tomography algorithms and selected emitter/detector implementations.
Support frame and cavity for air flow
A support frame at least partially surrounding a cavity through which a flow of air can pass without substantial interference.
Displaced electromagnetic emitters for cross-sectional illumination
A plurality of electromagnetic emitters displaced along the support frame and configured to emit electromagnetic radiation toward the cavity to illuminate at least a cross-section of the flow of air.
Displaced electromagnetic detectors for radiation detection
A plurality of electromagnetic detectors displaced along the support frame and configured to detect the electromagnetic radiation emitted from the electromagnetic emitters.
Illumination-pattern cycling, measurement acquisition, extinction-map reconstruction, and particle-characteristic determination
A controller configured to cycle on-and-off each of the plurality of electromagnetic emitters in an illumination pattern, acquire a measurement from each of one or more selected electromagnetic detectors during each on-cycle of an electromagnetic emitter, reconstruct, from a plurality of acquired measurements, an extinction map of the cross-section of the flow of air using a tomography algorithm, and determine one or more characteristics of particles in the flow of air from the reconstructed extinction map.
Tomography algorithm selection for reconstruction
The system wherein the tomography algorithm comprises an algorithm selected from iterative reconstruction, filtered backprojection, truncated singular value decomposition, and diffraction tomographic reconstruction.
Emitter types for electromagnetic emission
The system wherein each electromagnetic emitter is chosen from optical light emitters, monochromatic light generating emitters, monochromatic emitters with a spectral filter to emit monochromatic light, light emitting diodes, lasers, and emitters coupled to a fiber optic waveguide.
Detector types for electromagnetic detection
The system wherein each electromagnetic detector is chosen from a charge-coupled-device pixel, one or more charge-coupled-device pixels, or a fiber optic waveguide coupled to part of a charge-coupled device.
Wind-tunnel arrangement with sprayer and engine under test
A system further including a wind tunnel, a sprayer that injects particles into an air flow, an engine mount for an engine under test, and a tomography duct in the wind tunnel with a support frame and electromagnetic emitters and electromagnetic detectors between the sprayer and the engine mount.
Particle species selection
The system wherein the particles are chosen from water, supercooled water, or ice.
Across the independent and dependent claims, the system is defined by cycling electromagnetic emitters in an illumination pattern, acquiring detector measurements during emitter on-cycles, reconstructing an extinction map of a flow cross-section via a tomography algorithm, and determining particle characteristics from the reconstructed extinction map. Dependent claims further constrain the tomography algorithm choices and specify emitter and detector implementation options, and add a wind-tunnel-style experimental arrangement with an engine under test and selected particle species.
Stated Advantages
Not explicitly described in patent.
Documented Applications
real-time monitoring of ice/water clouds in NASA wind tunnels [procedural detail omitted for safety]
feedback/control of sprays [procedural detail omitted for safety]
engine intake instrumentation [procedural detail omitted for safety]
atmospheric particulates [procedural detail omitted for safety]
smoke stack emissions [procedural detail omitted for safety]
Interested in licensing this patent?