Abstract
Digital Particle-Image-Velocimetry was applied to investigate particle trajectories in a gas flow past a sphere. The particle displacement was determined by autocorrelation analysis of image sections. To enhance the signal/noise ratio a synthetic image with idealized particle pictures was generated from the real image. The autocorrelation function (ACF) was calculated using the Fast Hartley Transformation (FHT). The desired secondary maximum of this function was detected by an algorithm with subpixel resolution. A data validation step testing the plausibility of the velocity vectors completes the image analysis. Particle trajectories are traced with help of the particles' velocity vectors. The particle deposition on a sphere can be deduced from the course of these trajectories.
Similar content being viewed by others
Abbreviations
- Cu :
-
Cunningham correction
- e :
-
double distance between the limiting particle trajectory and the stagnation point axis
- f :
-
focal length
- H :
-
Hartley-Transform
- M :
-
enlargement factor
- S :
-
interference band spacing
- x :
-
coordinate
- y :
-
coordinate
- x p :
-
particle diameter
- x T :
-
droplet or sphere diameter
- V :
-
image as grey value function
- ν ∞.rel :
-
face velocity of droplet or sphere
- Δ :
-
particle image displacement
- Δx :
-
particle image displacement in x-direction
- Δy :
-
particle image displacement in y-direction
- η :
-
collection efficiency
- λ :
-
wavelength of the laser light
- μ L :
-
fluid viscosity
- ρ L :
-
fluid density
- ρ p :
-
particle density
References
Adrian, R. J. 1985: Multi-point vector measurement by pulsed Laser- Velocimetry with image compression. Symp. on fluid control and measurement, Papers of the Soc. of Instrument and Control Engineers, 1065–1078, Tokyo
Bracewell, R. H. 1990: Schnelle Hartley-Transformation. München: Oldenbourg
Brigham, E. O. 1985: FFT Schnelle Fourier-Tranformation, München: Oldenbourg
Dau, G.; Ebert, F. 1987: Determination of aerosol deposition on the front and wake side of spheres by gas-chromatography. J. Aerosol Sci. 18, 147–157
Hähner, F.; Ebert, F. 1992; Institut für Mechanische Verfahrenstechnik und Strömungsmechanik, Universität Kaiserslautern (personal communication)
Hartley, R. V. L. 1942: More symmetrical Fourier analysis applied to transmission problems, Proc. Inst. Radio Engrs. 30, 144–150
Liu, Z. C.; Landreth, C. C.; Adrian, R. J.; Hanratty, T. J. 1991: High resolution measurement of turbulent structure in a channel with Particle-Image-Velocimetry; Exp. Fluids 10; 301–312
Lourenco, L. M.; Krothapalli, A.; Smith, C. A. 1989: Particle-Image-Velocimetrie; Lecture Notes in Engineering (Ed.: Brebbia, C. A.; Orzag, S. A.), Vol. 45: Advances in Fluid Mechanics Measurements (Ed.: Gad-el-Hak, M.). Berlin Heidelberg New York: Springer
NAG Manual 1991: IBM FUJITSU FORTRAN Installation. NAG Ltd. Oxford
Merzkirch, W. 1990: Laser-Speckle-Velocimetrie. Lasermethoden in der Strömungsmeβtechnik (Ed.: Ruck, B.), 71–97 Stuttgart: AT-Fachverlag
Reeves, A. A. 1990: Optimized fast Hartley-transform for the MC68000 with applications in image processing. MS Thesis, Dartmouth College, Hannover, New Hampshire
Rusband, W. 1991: Image Manual, Department of Health & Human Services, Public Health Service, National Institutes of Health, Bethesda, Maryland
Schmidt, M.; Löffler, F. 1991: Das Strömungsfeld um eine Kugel bei kleinen und mittleren Reynoldszahlen (Re < 130); Chem. Ing. Tech. 63, 851–853
Schmidt, M.; Löffler, F. 1992 a: Determination of limiting particle trajectories by Particle-Image-Velocimetry, 5. Europ. Symp. Particle Characterization, Nürnberg
Schmidt, M.; Löffler, F. 1992b: Calculation of particle deposition on charged droplets. 2. Europ. Symp. Separation of Particles from Gases (PARTEC 92), Nürnberg
Walton, W. H.; Woolcock, A. 1960: The supression of air borne dust by water spray. Int. J Air Pollution 3, 129–153
Willert, C. E.; Gharib, M. 1991: Digital particle image velocimetry. Exp. Fluids 10, 181–193
Wozniak, K.; Wozniak, G.; Rösgen, T. 1990: Particle-Image-Velocimetry applied to thermocapillary Convection. Exp. Fluids 10; 12–16
Yao, C. S.; Adrian, R. J. 1984: Orthogonal compression and 1-D analysis technique for measurement of 2-D particle displacements in pulsed laser velocimetrie. Appl. Opt. 23, 1687–1689
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Schmidt, M., Löffler, F. Experimental investigations on two-phase flow past a sphere using digital Particle-Image-Velocimetry. Experiments in Fluids 14, 296–304 (1993). https://doi.org/10.1007/BF00189487
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00189487