E-JET performance using higher order modes
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abstract
Electroactive polymer synthetic jet actuators ("E-JETs") are a new lightweight, lowpower means of generating a synthetic jet for active flow control applications. The actuation method utilizes a thin ( 30 micron), pre-strained, low modulus, and circular dielectric elastomer membrane excited to operate at resonance to pump a working fluid into and out of a partially closed chamber. Based on device configurations tested to date, peak attainable nozzle velocity has been experimentally determined to be approximately 22 m/s at a nozzle exit diameter of 13mm and a frequency of approximately 250Hz without optimization. While performing frequency sweep characterization of the device, it was noted that certain higher membrane vibration modes induced significantly greater jet velocities than the first membrane mode due to the nonlinear nature of the system. A series of tests were performed using stroboscopic imaging techniques to identify the modes and correlate them qualitatively with the device performance. These initial tests verified the presence of modes approximating classical membrane modes in the system. A second series of tests was then performed using a scanning laser vibrometer to quantitatively correlate membrane mode shapes with overall device performance. The vibrometer tests experimentally attributed peak device performance to the presence of one particular higher order mode, approximating the fourth classical membrane mode shape. Copyright 2008 by the American Institute of Aeronautics and Astronautics, Inc.
