Two-Phase Wall Shear Stress Measurements in a Channel Flow Using PIV, Wall-Pressure and an Optical Sensor

摘要

Drag reduction in turbulent flows is a challenging topic for research and an important topic for engineers due to its potential application in several disciplines. Studies of changes of the turbulence properties in wall-bounded turbulent flows with either a passive or additive techniques provide knowledge to understand some of the physical principles that govern turbulence. The ability to forecast, modify and control turbulence has interesting practical applications in the nuclear, chemical, petroleum, chemical fields among others. Many drag reduction investigations have been performed with the injection of polymers and surfactants; however, a less number of studies that show the drag reduction with injected microbubbles in the boundary layer of channel flows are available in the literature. This study is an attempt to study the influence of microbubbles injection on the characteristics of turbulence and drag reduction. The need for energy savings and environmental protection is one of the motives for pursuing this investigation. Energy savings can be a direct result from an adequate control of turbulence.