Smart Control of Flow Separation around an Airfoil

Abstract

In order to construct a control system for flow separation around an airfoil, continuous jet type vortex generator and optical cantilever sensor for discriminating flow condition were developed. Blowing jet apertures of the vortex generator are placed in airfoil surface at 0 and 30 % chord. The jet apertures were aligned span-wise on the suction surface. Locations and interval of the apertures were decided according to the previous data on the flow separation at low and high attack angles of the MEL001 airfoil. Most distinctive feature of the present jet vortex generator is that it can produce single, longitudinal vortex with arbitrary strength and extent by controlling the jet velocity distribution across the aperture. The optical cantilever sensor was developed. It was installed at the trailing edge. The sensor has two functions: discrimination of flow direction and compensation of temperature fluctuation of flow. The flow around the airfoil is controlled by actuating of the vortex generator and information from the optical cantilever sensor. The vortex generator can be used not only as an actuator but also as a tracer discharger. The longitudinal vortices are discharged as tracer for the flow monitoring. The discharged tracer vortices accumulate information on the flow around the airfoil as they travel downstream. Thus the flow condition is monitored by the sensor at the trailing edge. The monitored signals were sent to the computer and analyzed and then feedback control signal is sent to the actuator.