Author(s): Toshimitsu Komatsu; Hideo Oshikawa; Mirei Takeuchi
Linked Author(s): Hideo Oshikawa
Keywords: Turbulence Modulation; Neutrally Suspended Particle; Oscillating Grid Turbulence; Wave Number Spectrum; Strouhal Number
Abstract: Turbulence modulation in a flow with neutrally suspended particles has been experimentally investigated. The turbulent field generated by an oscillating grid was adopted as a basic turbulent field. Since there is no mean shear flow in it, the steady state can be easily attained. In the present study, the spatial characteristics such as1-dimensional wave number spectra and integral length scales in multiphase turbulent flows have been examined on the basis of measurements by traversing FLV. The main results obtained are as follows: New eddies whose dimensionless wave number kd/2πis about 0. 2 are generated when neutrally suspended particles exist in the flow. The eddies seem to be those of wake due to a relative velocity between a particle and ambient fluid, because the value of kd/2πcorresponds to Strouhal number St found behind a rigid sphere in a uniform flow. Consequently, a wave number spectrum has a peak at around kd/2π=0. 2 if a comparably large number of spherical particles are contained in the flow.
Year: 1999