An experimental study on turbulence modification in the near-wall boundary layer of a dilute gas-particle channel flow

Jing Li, Hanfeng Wang, Zhaohui Liu*, Sheng Chen, Chuguang Zheng

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

62 Citations (Scopus)

Abstract

Turbulence modifications of a dilute gas-particle flow are experimentally investigated in the lower boundary layer of a horizontal channel by means of a simultaneous two-phase PIV measurement technique. The measurements are conducted in the near-wall region with y + < 250 at Re τ (based on the wall friction velocity u τ and half channel height h) = 430. High spatial resolution and small interrogation window are used to minimize the PIV measurement uncertainty due to the velocity gradient near the wall. Polythene beads with the diameter of 60 μm (d p + = 1.71, normalized by the fluid kinematic viscosity ν and u τ) are used as dispersed phase, and three low mass loading ratios (U m) ranging from 10 -4 to 10 -3 aretested.It is found that the addition of the particles noticeably modifies the mean velocity and turbulent intensities of the gas-phase, as well as the turbulence coherent structures, even at φ m = 0.025 %. Particle inertia changes the viscous sublayer of the gas turbulence with a smaller thickness and a larger streamwise velocity gradient, which increases the peak value of the streamwise fluctuation velocity (u+ ms) of the gas-phase with its location shifting to the wall. Particle sedimentation increases the roughness of the bottom wall, which significantly increases the wall-normal fluctuation velocity (v rms+) and Reynolds shear stress (- 〈u'v'〉 +) of the gas-phase in the inner region of the boundary layer (y + < 10). Under effect of particle-wall collision, the Q2 events (ejections) of the gas-phase are slightly increased by particles, while the Q4 events (sweeps) are obviously decreased. The spatial scale of the coherent structures near the wall shrinks remarkably with the presence of the particles, which may be attributed to the intensified crossing-trajectory effects due to particle saltation near the bottom wall. Meanwhile, the v rms+ and -〈u'v'〈 + of the gas-phase are significantly reduced in the outer region of the boundary layer (y + > 20).
Original languageEnglish
Pages (from-to)1385-1403
Number of pages19
JournalExperiments in Fluids
Volume53
Issue number5
Early online date30 Aug 2012
DOIs
Publication statusPublished - Nov 2012
Externally publishedYes

Keywords

  • Particle Image Velocimetry
  • Coherent Structure
  • Bottom Wall
  • Particle Image Velocimetry Measurement
  • Reynolds Shear Stress

ASJC Scopus subject areas

  • Computational Mechanics
  • Mechanics of Materials
  • General Physics and Astronomy
  • Fluid Flow and Transfer Processes

Fingerprint

Dive into the research topics of 'An experimental study on turbulence modification in the near-wall boundary layer of a dilute gas-particle channel flow'. Together they form a unique fingerprint.

Cite this