A Comparison of Subpixel Edge Detection and Correlation Algorithms for the Measurement of Sprays

Duke, Daniel J.; Honnery, Damon; Soria, Julio

doi:10.1260/1756-8277.3.2.93

Cited by 13 publications

(2 citation statements)

References 26 publications

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“…Since the interframe time ∆t is known, the average convective velocity is given by u = ∆x/∆t. The accuracy of this method depends upon the camera resolution, signal to noise ratio, timing accuracy and frame rate [30].…”

Section: Example Applicationsmentioning

confidence: 99%

A low-cost high-speed CMOS camera for scientific imaging

Duke¹,

Knast²,

Thethy³

et al. 2019

Meas. Sci. Technol.

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Non-intrusive temporally and spatially resolved measurements of dynamic phenomena are heavily reliant on high-speed (>1 kHz) digital scientific cameras. The cost of these cameras is a major constraint on the operation of many experimental and educational research facilities. In this paper we present a performance analysis of a low-cost high-speed CMOS camera, the Chronos 1.4. Developed for consumer use, we investigate its potential as a scientific camera. It uses a 12 bit Luxima LUX1310 CMOS sensor with 1280 × 1024 px at 6.6 µm pitch and 1 µs minimum global shutter. It is capable of recording at 1057 Hz at full frame and up to 38 kHz with a reduced field of view. It provides a number of features not typically found in low-cost consumer cameras, such as external triggering and shutter gating control, clock outputs, and raw binary data output. We test the linearity of the sensor response using a pulsed LED source and analyse the sensor performance in terms of noise, jitter and intensity lag. A quantitative demonstration of the camera's performance under realistic experimental conditions is demonstrated with an image correlation velocimetry measurement in a high-speed propellant spray. The camera compares favourably against several scientific high speed cameras from major manufacturers. The camera is well suited for high resolution forward-scattering and in-line imaging techniques such as schlieren, shadowgraphy, holography and bright-field microscopy. Spatial bias in the dark field noise floor makes it generally unsuitable for lowlight measurement conditions. However, the small footprint and low cost make it ideal as an educational tool and for multi-camera experiments. These tests were conducted independently of the manufacturer and the authors have no conflicts of interest to disclose.

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Section: Example Applicationsmentioning

confidence: 99%

A low-cost high-speed CMOS camera for scientific imaging

Duke¹,

Knast²,

Thethy³

et al. 2019

Meas. Sci. Technol.

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“…However, the transfer function caused by phase-contrast, beam hardening, scintillator properties, the optical path, and post-processing introduces a point spread function which blurs this edge. 33 The derivative of the edge profile intensity provides a line spread function (LSF) that can be approximated by a Gaussian curve whose width is described by its standard deviation, σ . Smaller values of σ indicate a sharper edge and smaller uncertainty of the edge position and thus the hole diameter.…”

Section: Effective Resolution and Uncertainty Analysismentioning

confidence: 99%

High-resolution X-ray tomography of Engine Combustion Network diesel injectors

Matusik

Duke

Kastengren

et al. 2017

International Journal of Engine Research

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The flow inside direct-injection diesel nozzles is strongly influenced by the local geometry. Deviations from the design geometry and nonuniformities along the fuel’s flow path can alter the expected spray behavior. The influence of small-scale variations in the internal geometry is not well understood due to a lack of data available to experimentalists and modelers that resolve such features. To address the need for more accurate geometry measurements that also quantify the error bounds on manufacturing variability, the 7-BM beamline of the Advanced Photon Source at Argonne National Laboratory has been customized to obtain high-resolution X-ray tomography of injection nozzles. In this article, we present results for several diesel injectors provided by the Engine Combustion Network. The imaging setup was optimized to measure dense metallic samples at high signal-to-noise ratio using projection imaging. To improve contrast, multiple images were recorded at each rotation angle. Phase shifting effects, which amplify the uncertainty in locating nozzle boundaries, were minimized by reducing the propagation distance of the X-rays between the nozzle and detector. Such improvements to the imaging technique enabled the nozzle hole diameter to be measured with an accuracy of 1.8 µm, which takes into account the pixel resolution as well as the properties of the imaging setup and the geometric analysis. The high spatial resolution allows the nozzle hole inlet corner radius to be azimuthally resolved. For the sample set under consideration, these new measurements reveal that non-hydroground injectors have a distribution of radii which typically vary by more than a factor of two. An azimuthally varying radius of curvature at the hole inlet is expected to result in highly asymmetric cavitation. Skeletal wireframe models of the nozzle hole geometries suitable for computational fluid dynamics mesh generation have been developed, in addition to full three-dimensional isosurfaces; these data have been made publicly available online.

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