Hydrogen bubble flow visualization and digital image analysis for drag reduction mechanism in wall turbulence with groove-riblet surface

作者：Chang Yue Feng; Jiang Nan^*; Xia Zhen Yan; Tian Yan

来源：Journal of Tianjin University, 2009, 42(9): 839-844.

• Coherent structure
• Comparative analysis
• Digital image analysis
• Digital image processing technique
• Drag reduction mechanism
• Experimental investigations
• Flow manipulation
• Groove-riblet surface
• High-speed
• Hydrogen-bubble flow visualization
• Lateral directions
• Lateral velocities
• Near-wall region
• Plate surfaces
• Quantitative analysis
• Riblets
• Spatial scale
• Turbulent boundary layers
• Two-dimensional planes
• Wall turbulence
• Water channels

The experimental investigation of drag reduction mechanism over micro-riblets surface in a turbulent boundary layer was carried out with hydrogen bubble flow visualization and digital image processing techniques. The burst phenomena of high-speed and low-speed streak flow structures in the near wall region of turbulent boundary layer was visualized over both smooth plate and riblet plate in an open-surface recirculating water channel. With ';comparison-between-frame'; quantitative analysis technique, the two-dimensional plane distributions of longitudinal and lateral velocity components were obtained through processing and analyzing hydrogen bubble flow visualization images. Comparative analysis of the hydrogen bubble flow visualization images of coherent structures in the near wall region over smooth plate and riblet plate was conducted. The spatial scale characteristics along longitudinal and lateral directions of high-speed and low-speed streak flow structures in the near wall region of turbulent boundary layer were studied over both smooth plate and riblet plate surface according to the two-dimensional plane distributions of longitudinal and lateral velocity components. The mechanism of drag reduction over micro-riblets surface in a turbulent boundary layer was analyzed according to coherent structure manipulation in wall turbulence.

• 出版日期2009
• 单位天津大学