A piezohydraulic actuator has been designed and tested for broadband flow control of a microjet actuator. This actuator is under development to understand fundamental flow characteristics near a pulsed flow microjet for active flow control on a number of aircraft structures including impinging jets, cavities, and jet inlets. Recent research has shown substantial reductions in flow separation and noise reduction using steady blowing microjets. This approach often leads to inefficiencies due to excessive mass flux that is typically bled off of an aircraft compressor. Reductions in mass flux without performance losses are desired by actively pulsing the microjet. A piezohydraulic actuator design is presented to investigate this concept. The actuator includes a piezoelectric stack actuator and hydraulic circuit to achieve sufficient displacement amplification to throttle a 400 μm diameter microjet. This system is shown to provide broadband pulsed flow actuation up to 900 Hz. Key parameters contributing to dynamic actuation are shown to include hydraulic fluid behavior, biased microjet air pressure, and voltage inputs to the stack actuator.

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