Rainbow Schlieren Deflectometry for Scalar Measurements in Fluid Flows

Agrawal, Ajay K.; Wanstall, C. Taber

doi:10.1615/jflowvisimageproc.2018028312

Cited by 18 publications

(10 citation statements)

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“…Results from numerical simulations are typically not obtained in the same way, and thus this validation process might be inconsistent. In contrast, although it used to be very difficult to obtain quantitative information of the density profile in flows by a schlieren technique, the integration and subsequent processing analyses can now be done with ease by conventional personal computers (Settles & Hargather 2017;Agrawal & Wanstall 2018). There have been some recent attempts to visualize the prominent characteristics of shock-containing microjets by quantitatively utilizing a computer-based imaging approach.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

et al. 2020

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Section: Introductionmentioning

confidence: 99%

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

et al. 2020

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Section: Introductionmentioning

confidence: 99%

“…The rainbow schlieren deflectometry is a modified form of the conventional schlieren such as the greyscale schlieren with a knife edge and color schlieren with a tricolor filter [1] [12] and it is different from the conventional schlieren in that the rainbow schlieren can capture density fields of flows with variable refractive index. In addition, the rainbow schlieren deflectometry can measure density fields of three-dimensional free jets by combining it with computed tomography [9] [10] [12]. A comprehensive and thorough review of the rainbow schlieren technique is presented by Agrawal and Wanstall [12], where methods to acquire quantitative density data including mathematical relationship, numerical algorithms, system design criteria, hardware issues, calibrations of rainbow filters, and so on are summarized.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the rainbow schlieren deflectometry can measure density fields of three-dimensional free jets by combining it with computed tomography [9] [10] [12]. A comprehensive and thorough review of the rainbow schlieren technique is presented by Agrawal and Wanstall [12], where methods to acquire quantitative density data including mathematical relationship, numerical algorithms, system design criteria, hardware issues, calibrations of rainbow filters, and so on are summarized. Recently, Ezoe et al [13] applied the rainbow schlieren deflectometry for leek peeler nozzle jets to improve the nozzle peeling performance and developed a new nozzle with higher removing potential for peeling leeks in comparison with the conventional nozzle.…”

Section: Introductionmentioning

confidence: 99%

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Application of Rainbow Schlieren Deflectometry for Jets from Round Laval Nozzles Followed by Cylindrical Ducts

Fukunaga¹,

Islam²,

Awata³

et al. 2021

JFCMV

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The jet from a round Laval nozzle followed by a cylindrical duct with an inner diameter of 10 mm and a length of 50 mm is investigated experimentally. The Laval nozzle has a design Mach number of 1.5. Quantitative flow visualization of the jet issued from the duct exit is performed over a range of nozzle pressure ratios from 2.0 to 4.5 using the rainbow schlieren deflectometry combined with the computed tomography to investigate the jet three-dimensional structure. The flow features of the near-field shock systems in the jets are displayed with the density contour plot at the cross-section including the jet centerline. Effects of the nozzle pressure ratio on the density profile along the jet centerline are clarified quantitatively. In addition, a comparison between the present experiment and the previous one with a conventional Laval nozzle for jet centerline density profiles is carried out to examine the effect of the cylindrical duct. Furthermore, the three-dimensional structures of overexpanded and underexpanded jets are demonstrated with the isopycnic surfaces to visualize the internal flow features.

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“…More recently, Wernet and Stiegemeier (2017) have applied BOS for the micron-scale density field of a free jet issued from a small rocket engine. Another simpler optical technique for visualizing jet density fields comparable to BOS might be the rainbow schlieren deflectometry (Takano et al 2016;Maeda et al 2018;Agrawal and Wanstall 2018;Mariani et al 2020). This technique is a modified approach based on the conventional color schlieren.…”

Section: Introductionmentioning

confidence: 99%

Quantitative Flow Visualization of Slightly Underexpanded Microjets by Mach–Zehnder Interferometers

Sugawara

Nakao

Miyazato

et al. 2020

Flow Turbulence Combust

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The Mach–Zehnder interferometer with the finite fringe setting is applied for a shock-containing microjet issued from an axisymmetric convergent nozzle with an inner diameter of 1.0 mm at the exit. Experiments are performed at a nozzle pressure ratio of 3.0 to produce a slightly underexpanded sonic jet where the Reynolds number, based upon the diameter and flow properties at the nozzle exit, is $$4.45 \times 10^4$$ 4.45 × 10 4 . The reconstruction of the jet density field is performed using the Abel inversion method under the assumption of an axisymmetric flow as well as the Fourier transform method for the phase shift analyses of interferograms. The three-dimensional density field of a shock-containing microjet can be captured with a spatial resolution of 4 $$\upmu$$ μ m, and the near-field shock structure inside the jet plume is shown in the density contour plot at the cross-section including the jet centerline. In addition, the density field of the microjet is illustrated with various techniques, including representation such as the vertical-knife-edge schlieren, the horizontal-knife-edge schlieren, the bright-field schlieren, and the shadowgraphy. In addition to experiments, the Reynolds averaged Navier–Stokes (RANS) simulation with the SST k–$$\omega$$ ω turbulence model is carried out to model the microjets, and a quantitative comparison with the experiments is performed. The jet centerline density profile obtained by the present experiment is quantitatively compared with those from the previous Mach–Zehnder interferometer, the background oriented schlieren, as well as the RANS simulation.

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Rainbow Schlieren Deflectometry for Scalar Measurements in Fluid Flows

Cited by 18 publications

References 0 publications

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

Three-dimensional reconstruction of a microjet with a Mach disk by Mach–Zehnder interferometers

Application of Rainbow Schlieren Deflectometry for Jets from Round Laval Nozzles Followed by Cylindrical Ducts

Quantitative Flow Visualization of Slightly Underexpanded Microjets by Mach–Zehnder Interferometers

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