The optimization for the backward-facing step flow control with synthetic jet based on experiment

• Synthetic jet with non-linear oscillating piston actuator is newly developed.
• An in-looped design optimization system based on experimental data is proposed.
• The single-objective optimum state restrains separation dramatically.
• A multi-objective optimum scheme considering power consumption is constructed.
• Flow control mechanism of the new synthetic jet device is preliminarily revealed.

Active flow control, which has great application prospects in aerodynamic design, can restrain flow separation and reduce drag. In this paper, a newly developed synthetic jet device with non-linear oscillation of the reciprocating piston actuator into the pipe is introduced and applied to control flow field of backward-facing step. An in-looped design optimization system based on experimental data adopting hybrid searching algorithm is constructed and applied to optimize parameters of this synthetic jet device. The optimum state based on experiment restrains separation dramatically, which validates the efficiency of the design optimization strategy and the excellent performance of synthetic jet device. The optimum jet slot angle is 127.5° and the optimum frequency is 35 Hz. Then, power consumed in driving reciprocator is considered to derive a multi-objective optimum scheme. With theoretical analysis and experimental data of velocity profiles and Reynolds stress distributions, flow control mechanism of synthetic jet device is preliminarily revealed. The optimization process and the analysis of optimum state provide guidance to the design of active flow control devices.

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