Simultaneous Measurement of Velocity and Equivalent Diameter on Non‐Spherical Particles

Morikita, Hiroshi; Hishida, Koichi; Maeda, Masanobu

doi:10.1002/ppsc.19940110310

Cited by 14 publications

(3 citation statements)

References 15 publications

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“…The images of the particles are processed and analyzed at high particle velocities to find velocity, shape, orientation, and size of particles, regardless of their shape (spherical or nonspherical) and optical property such as refractive index and particle emissivity. The principle of the Shadow Doppler Particle Analyzer was given in detail by Morikita et al (1994Morikita et al ( , 1995, and the application of the SDPA continues to be an area of research. The objective of this study was to develop a laboratory in-line optical probe for the simultaneous determination of particle shape, size, and velocity in a solid particle-laden process flow.…”

Section: Introductionmentioning

confidence: 99%

Optical Probe for the In-Line Determination of Particle Shape, Size, and Velocity

Petrak

Rauh

2006

Particulate Science and Technology

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A laboratory optical probe was developed to simultaneously determine the following particle characteristics: circularity, particle projection area, equivalent diameter of a circle, length of the particle outline or perimeter, maximum chord length, aspect ratio, and particle velocity. Using the projection area and the perimeter, the particle shape factor circularity can be determined. The aspect ratio was approximated by the ratio of the equivalent diameter to the maximum chord length. The basic measuring principle is multi-point scanning of the particle shadow image by a line of optical fibers. In addition, the particle velocity can be measured by a differential spatial filter of optical fibers. These fibers are step index fibers with a core diameter of 64 mm and cladding of 70 mm. The shadow image of a single particle was generated by a parallel laser beam. The uncertainty of the measured circularity and aspect ratio was investigated by using metal wires with diameters of 0.12 to 0.5 mm as test particles with known circularity and aspect ratio. The standard deviations were 1.9% for the circularity and 15.5% for the approximated aspect ratio. In addition, the optical probe system was investigated by measurements of solid particles with different shapes. As an example, the results of sand, marjoram seed, and metallic oxide particles are shown. Using 1000 sand particles, the correlation between equivalent diameter and particle velocity could be demonstrated. The presented configuration of the optical probe is applicable in the size range of 0.1 to 0.9 mm and up to a particle velocity of 5 m=s.

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Section: Introductionmentioning

confidence: 99%

Optical Probe for the In-Line Determination of Particle Shape, Size, and Velocity

Petrak

Rauh

2006

Particulate Science and Technology

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“…Size and velocity measurement of particles can be achieved by various laser-based techniques, some of which are commercially available. One technique is an intensitybased one, in which the intensity of the light scattered by a particle into particle size is interpreted using a known calibration relationship (Morikita et al 1994). In the case of particles with absorbing media and irregular shape, the intensity of diffracted light is especially useful because it is much less sensitive to the particle shape and its optical properties than are other approaches which use refraction and reflection modes.…”

Section: Introductionmentioning

confidence: 99%

Application of shadow Doppler velocimetry to paint spray: potential and limitations in sizing optically inhomogeneous droplets

Morikita

Taylor

1998

Meas. Sci. Technol.

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This paper reports size measurement of droplets with optically inhomogeneous media by shadow Doppler velocimetry (SDV), which can provide spatially and temporally precise in situ readings of the size and velocity of a single particle with irregular shape and with arbitrary optical properties of the particle medium. In this work, water, instant coffee solution and water-based paint with various solid contents were measured to evaluate the capability and limitations of the measurement. The experiment with instant coffee solutions of 2 and 5% (wt:wt), which contained 10 µm discrete particles, atomized by a standard paint spray gun, demonstrated that the accuracy of sizing was not affected by the optical properties of the medium. Insensitivity to the optical properties is one of the primary advantages of SDV over the other optical, single-particle sizing methods. As a further demonstration, paint samples atomized by the same gun containing solid flakes of nominal diameter 25 µm were also measured. The results revealed a spatially uniform arithmetic mean diameter of 30 µm and suggested that the atomization characteristics were influenced in the highest flake volume fraction case (red paint containing mica, 1.5%) with the result that the mean diameter was 20% larger than that of a similar paint with a smaller flake volume fraction (green paint containing aluminium, 0.4%). It was also found that the measurable number density is limited to no more than 1000 droplets cm −3 in the case of droplets with an average size of 20 µm.

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“…he nce s imultaneous meas ure me nt o f the ve loc ity and size of particl es, and o f the mean gas fl o w a lso, is the re fo re necessa ry fo r the qu antifi cati o n of the aerody na mic c lea n up. T ec hniques fo r sizin g a n irreg ul a r di spersed phase are still at a n earl y stage o f develo pme nt a nd in c lude, fo r exa mpl e , ho log raphy [5) , the vi s ibility o f a Do ppl e r s ig na l [6], imag in g [7 1 a nd arg uabl y th e most wide ly applied tec hnique the a m plitude of difft·acti ve lysca tte red li ght [8][9][10][11][12][13][14] . Us ua ll y, in a pplicati o ns fo r pul veri sed coal combu sti o n th e s izing beam has to pass throug h g lass w indo ws whi c h are subj ect to un co nt ro ll ed mo ve me nt due to th erm a l ex pa ns io n, makin g the ma inte na nce of o ptica l a li g nm e nt a diff"i c ult tas k [I OJ.…”

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confidence: 99%

Shadow Doppler Velocimetry for Simultaneous Size and Velocity Measurements of Irregular Particles in Confined Reacting Flows

Maeda¹,

Morikita²,

Prassas³

et al. 1997

Part & Part Syst Charact

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We report the application of the Shadow Doppler Velocimeter (SDV) for spatial precise, simultaneous measurement of the size and velocity to assess the particle retention performance of a laboratory, 1/6 scale, 10 kW vertically‐fired atmospheric model of the pressurised pulverised‐coal furnace of Reichert et al. [1]. The SDV is based on the imaging of a conventional LDV probe volume onto a linear photodiode array and has the advantage over other sizing methods for irregular particles that it is tolerant of the optical misalignment and fouling which are inevitable when passing laser beams through windows in such furnaces. The size and two components of velocity of burning coal particles were measured in the present geometry which has 172 mm furnace diameter and 40 mm lateral exit duct diameter and a calculated exit bulk velocity of 4 m/s, evaluated at 300 K. The Sauter mean diameter of the particles is, within the experimental error, uniform at about 40 μm in the vertical profile normal to the axis of the exhaust pipe, 34.5 mm upstream of the exit. Coal particle velocities in the near‐exit region are directed towards the exit, closely following the gas‐phase velocities. Both these observations imply that particle retention efficiency due to streamline curvature is low and extrapolation suggests that there will be even less at large scales.

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Simultaneous Measurement of Velocity and Equivalent Diameter on Non‐Spherical Particles

Cited by 14 publications

References 15 publications

Optical Probe for the In-Line Determination of Particle Shape, Size, and Velocity

Optical Probe for the In-Line Determination of Particle Shape, Size, and Velocity

Application of shadow Doppler velocimetry to paint spray: potential and limitations in sizing optically inhomogeneous droplets

Shadow Doppler Velocimetry for Simultaneous Size and Velocity Measurements of Irregular Particles in Confined Reacting Flows

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