Active control of turbulent boundary layer using an array of piezo-ceramic actuators

Abstract

This paper presents preliminary results from an experimental exploration on drag reduction in a turbulent boundary layer using an array of piezo-ceramic actuators. The actuator array consisting of 16 actuators can generate wall-normal oscillations and, given a phase shift between two adjacent actuators, a spanwise travelling wave. A sinusoidal waveform with four different amplitudes was investigated while oscillating in a wide range of frequencies. The preliminary results showed that about 5% reduction in drag could be obtained based on the measurement of a hot-film flush-mounted on the wall. A drag increase up to 20% was also observed when the actuator array worked in large amplitudes and high oscillation frequencies. The possible mechanism of drag reduction behind this control technique was discussed. Investigations are on-going to use different control strategies such as different actuation signals, spanwise travelling wavelengths and speeds, etc. in order to achieve better results in terms of drag reduction.