Özet:

The paper studies the behaviors of synthetic jets under the excitation of cavity resonance which is produced by an isolated two-dimensional actuator. A cross hot-wire was used to obtain measurements within the velocity field. This research revealed a number of notable phenomena, such as the appearance of vortex pairs only in the vicinity of orifice exit as well as their rapid dissipation downstream. Our results of analysis of the plane velocities of the synthetic jets indicate that effective flow control can be achieved only in regions close to the orifice. It is interesting to note that a linear relationship could be obtained only by taking the logarithm of mean velocity ( u - ) as well as downstream distance ( x ) in different transverses, and by using a curve fitting then linear relations can be obtained. The slopes of synthetic jets under excitation of cavity resonance were between –7/10 and –3/5, which represents a sine wave of 160 Hz on 15 V. The original time-domain data was then converted using fast Fourier transform to the show power spectrum in order to reveal more about the flow behavior of synthetic jets. Characteristic frequencies were identified at 80 Hz and 160 Hz in the initial center of the orifice. The former frequency (80 Hz) can be attributed to the collision of the upper vortex and lower vortex of the synthetic jet. The latter frequency (160 Hz) refers to the excitation frequency of the signal source. Following the development of the synthetic jet, the excitation frequency of 160 Hz eventually disappeared downstream but the characteristic frequency of 80 Hz remained until x / H = 8. These experimental results make a valuable contribution to the further development of flow control in the future.

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