Anti-PIV type 1 Monoclonal antibody, Clone C1493M

The authors have presented results of an experimental investigation into the velocity field in a turbulent boundary layer behind a thin (0.00045 m) three-dimensional plate. The chord of the plate (streamwise length) was equal to 0.55 delta (delta is the boundary-layer thickness), and its width, to 1.0 delta. The plate was installed at a zero angle of attack at the center of a water channel at a distance of 0.09 delta from the surface. Velocity-field measurements have been performed by the Particle Image Velocimetry method at the Reynolds number Re-h = 7750 calculated from the channel half-width and the velocity at the center of the channel. It has been shown that the average velocity increased in a logarithmic region of the boundary layer at a distance of its three thicknesses behind the plate. Longitudinal-velocity pulsations decreased in the buffer region of the boundary layer, but grew in the logarithmic region. Vertical pulsations only decreased to a distance of 0.8 delta behind the plate, but downstream they were higher than in an unperturbed boundary layer. The high resolution of the velocity field (50.10(-6) m) has made it possible to determine shear stresses on the wall from the velocity gradient in a laminar sublayer. Shear stresses on the surface behind the plate decreased in the interval where a growth in the average velocity in the logarithmic region was noted. Maximum reduction in the shear stresses occurred at a distance of 1.8 delta and amounted to similar to 33%. The influence of edge effects was manifested in the less intense reduction on shear stresses in the shorter interval behind the plate.

Liquid-phase turbulence plays a vital role in determining various gas-liquid two-phase flow parameters, such as void fraction distribution, bubble morphology, bubble-bubble interactions, and interfacial area concentration. In this study, a two-phase flow database including both the gas- and liquid-phases measurements was developed focusing on three bubbly flow conditions in an air-water two-phase flow loop with a vertical one-inch diameter circular pipe test section. A particle image velocimetry (PIV) system integrating an optical phase separation method, i.e., the planar laser-induced fluorescence (PLIF) technique using fluorescent particles and optical filtration, was applied to measure the liquid-phase turbulence information, including the time-averaged velocity, Reynolds stress, and turbulent kinetic energy for the liquid phase. The PIV measurements were taken at three ports along the test section at 14.5, 51.5, and 88.5 pipe inner diameters downstream of a bubble injector. In addition, a double-sensor conductivity probe was used to measure radial distributions of the local time-averaged void fraction and gas velocity. The measured liquid-phase turbulence was used to benchmark Sato's turbulence model considering the bubble-induced shear stress for the three tested bubbly flows. The benchmark results showed good agreement between the PIV measurements and model predictions. In the two bubbly flows tested that have low void fractions being less than 3%, the effect of the bubble-induced turbulence was found not significant. However, the bubble-induced shear stress becomes important with the increase of the void fraction.