When synthetic jet actuators are used to control flow separation in practical situations, it is anticipated that the orifices will be distributed in the form of an array. Wind tunnel experiments were conducted to investigate the effect of the location and number of these actuators on boundary layer separation. Three synthetic jets were located upstream of the separation point in undisturbed flow, and the mean and root mean-square (RMS) velocity profiles were measured at several axial locations within the separated flow region. This paper reports the effect of actuator placement and the integrated effectiveness of two and three synthetic jets with different forcing voltages and frequencies.
The flow produced by a synthetic jet actuator located in one wall of a microchannel is investigated using computational fluid dynamics (CFD) simulations. In the case of no cross-flow, the ejected vortices travel to the opposite wall and replenish the remains of the vortex left behind from the previous cycle. When cross-flow is added, the vortex penetration increases with both stroke length and frequency. The flow in the cavity appears to be nearly symmetrical, with the greatest effect seen near the orifice. In the orifice itself, three-dimensional effects are more noticeable with decreasing jet-to-cross-flow momentum ratio. The microchannel cross-flow causes the vortices to tumble about their transverse axis, the effect of which also increases with decreasing jet-to-cross-flow momentum ratio.
The synthetic jet actuator is a novel means of applying flow control that lends itself to incorporation into micro- electro-mechanical systems. Experimental and computational studies of the flow generated by this actuator are presented and discussed. The synthetic jet is seen to resemble a steady turbulent jet. Self-similarity is, however, achieved closer to the orifice in the case of the synthetic jet, and this is consistent with the observation from the numerical simulations that a main vortex is trapped close to the orifice. This main vortex merges with the secondary vortex that is generated at the circumference of the orifice during each cycle of oscillation of the actuator membrane. The effect of synthetic jets on wake flows and flames has also been examined. Preliminary results of these investigations suggest that synthetic jets can significantly reduce drag and enhance mixing.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.