Intermittent round jet controlled by lateral pulse-modulated synthetic jets
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A round air jet was actively controlled by a pair of lateral control jets. The control jets were generated by a pair of opposing synthetic jet actuators, which were driven by the pulse-modulated sinusoidal signal. Two carrier frequencies were tested, namely 160 Hz and 840 Hz. Moreover, control jets driven by un-modulated sinusoidal signals were also tested. An unforced continuous jet was used as the reference case, and for all cases, the Reynolds number of the main round jet was 1570 (related to the nozzle exit diameter of 10 mm). Experiments (flow visualization and hot-wire anemometry) revealed that the flow control caused a suppression of the jet core and a more rapid jet flow decay. In addition, the pulse modulation caused jet intermittency that was distinguished by the periodicity of the time-averaged and fluctuating velocity components. For the case of the lower carrier frequency of 160 Hz, a flapping motion of the controlled jet occurred and the jet formed a zigzag pattern.
KeywordsFlow control Pulse modulation Synthetic jet Flow visualization Hot-wire anemometry
We gratefully acknowledge the support of the Grant Agency of the Czech Republic—Czech Science Foundation (project no. 16-16596S) and the institutional support RVO: 61388998.
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