LDV Measurement of Turbulent Boundary Layer Flow under Streamwise Traveling Wave Control for Drag Reduction

Abstract

Drag reduction effect of travelling wave control for turbulent boundary layer flow is measured by laser doppler velocimetry (LDV). Travelling waves are generated on a rubber sheet by oscillation of a piezoelectric actuator. Experiment apparatus is consist of 1.5 m of run up section and 1 m of testing section where the rubber sheet is installed. Experiment is carried out in the condition of mainstream velocity U_∞ = 3m/s, and momentum thickness-based Reynolds number Re_θ ~ 1500 at the center of the testing section. Friction drag coefficient C_f is calculated by integrated velocity distribution within 3% of uncertainty.