抄録
Effects of ultrasonic vibrations on turbulent (Re=7000±50) square-duct flow were investigated experimentally by means of LDV. Ultrasound was introduced into the flow by Langevin PZT-type transducers attached to the trapezoidal horn. Three cases of horn arrangements were investigated: the horn is located at the sidewall near the bottom, at the corner between sidewall and bottom, and at the center of the sidewall. Driven frequency and power supplied to transducers were 45±2 kHz and mainly 20 W respectively. Results show that acoustic streaming varies the distribution of Reynolds shear stress, and its change is explained by conventional momentum transfer theory. The experiment varying ultrasonic power shows that the region of ultrasonic vibration can be adjusted in case that the horn is located at the sidewall near the bottom, since this case is less affected by inertia of main flow compared with other cases.
