An image measurement system by means of statistical analysis has been developed. The number of tracer particle passing in a time is proportionate to the speed when the concentration of particle is uniform through the flow field. The method evaluates the flow speed by means of the probability of the tracer particle passing which can be measured through the probability of tracer-edge passing. The difference function of binarized image data gives tow pulse-like signals in a particle edge, and the interval and period of the signal are inversely proportional to the flow speed, and that form is dependent on only the shutter time. The mean of the absolute value of difference function obtained from binarized image data is used as the measure of flow speed, and is estimated by means of the ensemble average of the measured data. The absolute value of flow velocity can be obtained through the system, and it is suitable for the measurement of time-mean velocity. Measurement of rotating speed of particle patterned disk and wake distribution of a circular cylinder in low Reynolds number has been made. A correction method considering the difference of particle concentration has been proposed, and applied on a rotating disk which has two areas of different particle pattern concentration. The measurement system can be applied not only to the 2-D flow field but also the 3-D, and will decrease the measurement time of wake distribution compared with ordinary devices.

  • Supplemental Notes:
    • J Kansai Soc Naval Architects, n 224, Sept 1995, p 27 [8 p, 7 ref, 14 fig]
  • Authors:
    • Nishio, S
    • Okuno, T
    • Kimoto, N
  • Publication Date: 1995


  • Japanese

Subject/Index Terms

Filing Info

  • Accession Number: 00718715
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Mar 27 1996 12:00AM