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Title: A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry

Abstract

In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. Here, to ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortion quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches.

Authors:
 [1];  [1];  [2];  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  2. Korea Institute of Machinery and Materials, Daejon (Korea)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
OSTI Identifier:
1327911
Report Number(s):
SAND-2016-9612J
Journal ID: ISSN 0957-0233; 647762
Grant/Contract Number:
AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Measurement Science and Technology
Additional Journal Information:
Journal Volume: 27; Journal Issue: 8; Journal ID: ISSN 0957-0233
Publisher:
IOP Publishing
Country of Publication:
United States
Language:
English
Subject:
33 ADVANCED PROPULSION SYSTEMS; particle image velocimetry; optical distortion; swirl-plane; re-entrant piston geometry; ray tracing; back-projection; diesel engine

Citation Formats

Zha, Kan, Busch, Stephen, Park, Cheolwoong, and Miles, Paul C. A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry. United States: N. p., 2016. Web. doi:10.1088/0957-0233/27/8/085201.
Zha, Kan, Busch, Stephen, Park, Cheolwoong, & Miles, Paul C. A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry. United States. doi:10.1088/0957-0233/27/8/085201.
Zha, Kan, Busch, Stephen, Park, Cheolwoong, and Miles, Paul C. Fri . "A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry". United States. doi:10.1088/0957-0233/27/8/085201. https://www.osti.gov/servlets/purl/1327911.
@article{osti_1327911,
title = {A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry},
author = {Zha, Kan and Busch, Stephen and Park, Cheolwoong and Miles, Paul C.},
abstractNote = {In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. Here, to ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortion quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches.},
doi = {10.1088/0957-0233/27/8/085201},
journal = {Measurement Science and Technology},
number = 8,
volume = 27,
place = {United States},
year = {Fri Jun 24 00:00:00 EDT 2016},
month = {Fri Jun 24 00:00:00 EDT 2016}
}

Journal Article:
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  • Conventional particle image velocimetry (PIV) configurations require a minimum of two optical access ports, inherently restricting the technique to a limited class of flows. Here, the development and application of a novel method of backscattered time-gated PIV requiring a single-optical-access port is described along with preliminary results. The light backscattered from a seeded flow is imaged over a narrow optical depth selected by an optical Kerr effect (OKE) time gate. The picosecond duration of the OKE time gate essentially replicates the width of the laser sheet of conventional PIV by limiting detected photons to a narrow time-of-flight within the flow.more » Thus, scattering noise from outside the measurement volume is eliminated. In conclusion, this PIV via the optical time-of-flight sectioning technique can be useful in systems with limited optical access and in flows near walls or other scattering surfaces.« less
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  • X-ray images acquired on systems with image intensifiers (II) exhibit characteristic distortion which is due to both external and internal factors. The distortion is dependent on the orientation of the II, a fact particularly relevant to II's mounted on C arms which have several degrees of freedom of motion. Previous descriptions of distortion correction strategies have relied on a dense sampling of the C-arm orientation space, and as such have been limited mostly to a single arc of the primary angle, {alpha}. We present a new method which smooths the trajectories of the segmented vertices of the grid phantom asmore » a function of {alpha} prior to solving the two-dimensional warping problem. It also shows that the same residual errors of distortion correction could be achieved without fitting the trajectories of the grid vertices, but instead applying the previously described global method of distortion correction, followed by directly smoothing the values of the polynomial coefficients as functions of the C-arm orientation parameters. When this technique was applied to a series of test images at arbitrary {alpha}, the root-mean-square (RMS) residual error was 0.22 pixels. The new method was extended to three degrees of freedom of the C-arm motion: the primary angle, {alpha}; the secondary angle, {beta}; and the source-to-intensifier distance, {lambda}. Only 75 images were used to characterize the distortion for the following ranges: {alpha}, {+-}45 deg. ({delta}{alpha}=22.5 deg.); {beta}, {+-}36 deg. ({delta}{beta}=18 deg.); {lambda}, 98-118 cm ({delta}{lambda}=10 cm). When evaluated on a series of test images acquired at arbitrary ({alpha},{beta},{lambda}), the RMS residual error was 0.33 pixels. This method is targeted at applications such as guidance of catheter-based interventions and treatment planning for brachytherapy, which require distortion-corrected images over a large range of C-arm orientations.« less