An Investigation on Fundamental Characteristics of Excited Synthetic Jet Actuator Under Cavity and Diaphragm Resonances

This paper experimentally studies the basic characteristics of an isolated two-dimensional synthetic jet actuator (SJA) and two resonance frequencies found at 40 Hz and 160 Hz, which are respectively corresponding to the resonance of diaphragm and resonance of cavity of SJA, Data indicate that the former is independent of various excitation waveforms, excitation voltages and exit area of the SJA orifice. The latter is only associated with the exit area of the orifice. In addition, the dimensionless stroke length (Ld) is proportional to the Reynolds number of the exit velocity for the diaphragm resonance at various excitation voltages. As for the cavity resonance, the important result is that the dimensionless stroke length is proportional to Re3/2 for all four different excitation voltages and the effective neck length (l’) doesn’t keep constant with the varying exit area of orifice. That is, the l’ increases linearly with the increasing A2/3. Regarding the relationship among the maximum ejection velocity (Ūe, max), mean ejection velocity (Ū) and the resonance frequency of cavity (fc) at various voltages of excitation, both Ūe, max and Ū are inversely proportional to the fc3/2 in this study. The current experimental results are expected to be useful for designing a synthetic jet actuator for real applications.