New wall motion actuator using magnetic fluid and elastic membrane for laminar flow control

A new wall motion actuator for the control of boundary layer flow is presented. The actuator consists of a magnetic fluid layer with an elastic membrane surface and coil system. The vertical motion of the elastic membrane is generated when the magnetic fields are applied to the magnetic fluid. It is possible to control the wall motion by the adjustment of the electric current to the coils. The static and dynamic characteristics of the new actuators have been experimentally investigated. The effectiveness of the actuator for laminar flow control has been shown via wind tunnel testing. Two-dimensional travelling waves, or Tollmien-Schlichting waves (T-S waves), have been effectively attenuated by using the new actuator.