Behaviors and Effects of Movable Objects in Supersonic Flows

In the present paper, to enhance the supersonic mixing, a new concept of a movable object is proposed. A movable object is defined an object, or a set of objects, which is supported in such manners that it can move, especially vibrate or flutter, in a flow. Several examples of movable objects are also presented, for instance rubber sheet, hinged plates and so on. To examine the probability of movable objects being able to be applied for mixing enhancement, their behavior, flutter characteristics and effects were investigated experimentally. The schlieren images show that the flutter limits with respect to the sizes of movable objects and the flow conditions exist. Moreover, they indicate that movable objects can vibrate violently, i.e. with quite large frequencies and amplitudes. The root mean square distributions of the Pitot pressure fluctuations show that the flutter of movable objects intensifies the Pitot pressure fluctuations and extends the fluctuation region remarkably, which implies that quite strong and large dynamic vortices are generated. All the results imply that the flutter of movable objects stirs the supersonic flow violently, therefore meaning that it has quite large enhancement effects on the supersonic mixing. That is, movable objects are expected as effective vortex generators.