Characterization of fluorescent polystyrene microspheres for advanced flow diagnostics

Maisto, Pietro; Lowe, K. Todd; Byun, Guibo; Vercamp, Max; Danley, Jason E.; Koh, Brian D.; Tiemsin, Pacita I.; Danehy, Paul M.; Wohl, Christopher J.

doi:10.2514/6.2013-3168

Cited by 4 publications

(6 citation statements)

References 9 publications

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“…The present work has the focus of finding and applying safe fluorescent dyes to dope seed particles that can be used for LIF and flow diagnostics, such as PIV or laser Doppler velocimetry (LDV). Past work has used dichlorofluorescein (DCF) doped fluorescent particles for single particle LDV measurements [20,29,30]. However, when extended to planar PIV measurements, it was found that the DCF particles did not provide an adequate fluorescent signal for particle imaging (estimates from [29] indicate approximately 50 times weaker signals than exhibited in current results).…”

Section: Measurement Science and Technologymentioning

confidence: 55%

“…Using fluorescent light for PIV, rather than Mie scattering, has been used on the macro scale in water flows [15,16] and has had numerous applications in microscale PIV [17,18]. The technique is difficult to implement in a gas flow, which requires small particles and safe dyes due to inhalation concerns [19,20]. Fluorescent seed has been used on a few occasions for PIV in two phase flows, such as fuel injection into air [21,22].…”

Section: Measurement Science and Technologymentioning

confidence: 99%

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Improvements in laser flare removal for particle image velocimetry using fluorescent dye-doped particles

Petrosky

Lowe

Danehy

et al. 2015

Meas. Sci. Technol.

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Laser flare, or scattering of laser light from a surface, can often be a major issue in particle image velocimetry (PIV) involving solid boundaries in the flow or a gas–liquid interface. The use of fluorescent light from dye-doped particles has been demonstrated in water applications, but reproducing the technique in an airflow is more difficult due to particle size constraints and safety concerns. The following work presents fluorescent Kiton Red 620 (KR620)-doped polystyrene latex microspheres as a solution to this issue. The particles are small and narrowly distributed, with a mean diameter of 0.87 and diameter distribution standard deviation of 0.30 . Furthermore, the KR620 dye exhibits much lower toxicity than other common fluorescent dyes, and would be safe to use in large flow facilities. The fluorescent signal from the particles is measured on average to be 320 ± 10 times weaker than the Mie scattering signal from the particles. This reduction in signal is counterbalanced by greatly enhanced contrast via optical rejection of the incident laser wavelength. Fluorescent PIV with these particles is shown to eliminate laser flare near surfaces, allowing for velocity measurements as close as 100 to the surface. In one case, fluorescent PIV led to velocity vector validation rates more than 20 times that of the Mie scattering results in the boundary layer region of an angled surface.

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Section: Measurement Science and Technologymentioning

confidence: 55%

Section: Measurement Science and Technologymentioning

confidence: 99%

Improvements in laser flare removal for particle image velocimetry using fluorescent dye-doped particles

Petrosky

Lowe

Danehy

et al. 2015

Meas. Sci. Technol.

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“…A first study made use of non-fluorescent 2 µmdiameter PSL particles [3]. A second study made use of 0.87 µm-diameter PSL particles doped with KR620, manufacturedin a manner similar as described in [14]. The tracers are in a water solution placed in an atomizer (TSI six-jet 9306) and introduced in the air above the outlet of the nozzle.…”

Section: B Two Phase Experimentsmentioning

confidence: 99%

“…The present work brings together multidisciplinary efforts from teams of researchers at NASA Langley Research Center, George Washington University and Virginia Tech with a focus on finding and applying safe fluorescent dyes to dope seed particles that can be used for LIF and flow diagnostics, such as PIV or Laser Doppler Velocimetry (LDV). Past work has centered around Dichlorofluorescein (DCF) and KR620 dye-doped PSLs as safe alternatives for LIF, with Kiton Red exhibiting promising results [2,14,15]. The KR620 doped PSL particles used in the present work had 0.87 micron diameter and were developed using an improved proprietary version compared to that initially described in [15].…”

Section: Introductionmentioning

confidence: 99%

Particle Image Velocimetry Applications Using Fluorescent Dye-doped Particles

Petrosky

Maisto

Lowe

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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Polystyrene latex sphere particles are widely used to seed flows for velocimetry techniques such as Particle Image Velocimetry (PIV) and Laser Doppler Velocimetry (LDV). These particles may be doped with fluorescent dyes such that signals spectrally shifted from the incident laser wavelength may be detected via Laser Induced Fluorescence (LIF). An attractive application of the LIF signal is achieving velocimetry in the presence of strong interference from laser scatter, opening up new research possibilities very near solid surfaces or at liquid/gas interfaces. Additionally, LIF signals can be used to tag different fluid streams to study mixing. While fluorescence-based PIV has been performed by many researchers for particles dispersed in water flows, the current work is among the first in applying the technique to micron-scale particles dispersed in a gas. A key requirement for such an application is addressing potential health hazards from fluorescent dyes; successful doping of Kiton Red 620 (KR620) has enabled the use of this relatively safe dye for fluorescence PIV for the first time. In this paper, basic applications proving the concept of PIV using the LIF signal from KR620-doped particles are exhibited for a free jet and a two-phase flow apparatus. Results indicate that while the fluorescence PIV techniques produce a signal roughly 3 orders of magnitude weaker than Mie scattering, they provide a viable method for obtaining data in flow regions previously inaccessible via standard PIV. These techniques have the potential to also complement Mie scattering signals, for example in multi-stream and/or multi-phase experiments.

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“…Alternatively, laser flare reduction may be accomplished with the use of fluorescent tracer particles; their Stokes-shifted light may be collected through a long-pass filter that blocks surface reflections at the laser's wavelength. Fluorescent PIV has been used in water-based experiments [Poussou and Plesniak (2006)], but is more challenging for gas flows, which require smaller particles and careful consideration of particle inhalation hazards [Maisto et al (2013)]. For example, the study by Chennaoui et al (2008) successfully demonstrated flare reduction with fluorescent PIV in air, but made partial use of hazardous materials that warranted protective measures.…”

Section: Introductionmentioning

confidence: 99%

Fluorescent PIV using Atomized Liquid Particles

Acharya¹,

Lowe²,

Ng³

2021

ISPIV21

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It is shown that aerosolized fluorescent particles generated using a Venturi-type atomizer, from a solution of fluorescent Kiton Red 620 dye in a water/glycol fluid, provide effective flow seeding for fluorescent PIV. The atomized liquid particles were found to be of acceptable size for PIV purposes, with 92% of detected particles by number concentration measuring < 1 μm in diameter. A PIV application was conducted in a wind tunnel (freestream velocity U∞ = 27 m/s), using the particles for measurement of the boundary layer flow approaching a forward-facing step (approach boundary layer momentum thickness Reynolds number of Reθ = 5930), to identify potential benefits in near-wall regions normally affected by unwanted laser reflections from tunnel surfaces. Particles were generated from solutions with dye molar concentrations of 2.5 × 10−3 and 1.0 × 10−2 mol/L, and PIV images were obtained for both elastic Mie scattering and filtered, Stokes-shifted fluorescent light. Raw images indicate that the fluorescence yield of the 1.0 × 10−2 mol/L solution provides PIV images with high contrast, even in the near-surface regions where Mie scattering images are highly affected by surface reflections. Boundary layer profiles are processed in the adverse pressure gradient region leading up to the forward-facing step, where the fluorescent PIV performed comparably to the most optimized Mie scattering PIV; both obtained data as near to the wall as 30 μm, or 2 viscous wall units in our flow of interest. These results indicate that the new seeding method holds excellent promise for near-surface measurement applications with more complicated three-dimensional geometries, where it is impossible to arrange PIV cameras to reject surface-scattered light.

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Characterization of fluorescent polystyrene microspheres for advanced flow diagnostics

Cited by 4 publications

References 9 publications

Improvements in laser flare removal for particle image velocimetry using fluorescent dye-doped particles

Improvements in laser flare removal for particle image velocimetry using fluorescent dye-doped particles

Particle Image Velocimetry Applications Using Fluorescent Dye-doped Particles

Fluorescent PIV using Atomized Liquid Particles

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