High Frequency Pulsed Microjet Actuation

Flow control theory and actuator development have been the subject of intense research for more than a decade for applications on various aircraft structures including fixed wings, cavity flow, rotor blades, and impinging jets.

The present invention comprises a piezoelectric actuator for varying the throat geometry of a microjet nozzle, thereby varying the characteristics of the microjet produced by the microjet nozzle. The inventive device is capable of producing pulsed flow and also rapidly variable flow in order to provide active control. To our knowledge, most of the actuators that are presently available suffer from a limited dynamic range, insufficient control authority, very high mass flow, complexity, size/weight and/or robustness. Piezoelectric materials, in particular, are used in stack actuator configurations for high bandwidth nanoprecision control applications which makes it ideal for actively throttling an array of microjets. The direct conversion of electrical energy to mechanical energy provides unique capabilities when coupled to an actively deforming supersonic nozzle.

Applications:

• The proposed actuator can be incorporated into a wide variety of known flow control systems and because it is so responsive in the frequency domain, an active control system (using feed-back and/or feed-forward control loops) can be used. The control system can even vary the frequency in real time in order to disrupt unwanted isolations in the flow.
• This invention should be of interest to a whole array of aerospace and aviation stakeholders who are actively pursuing Active Flow Control for the current and Next Generation of air and space vehicles. These include commercial aircraft manufacturers, e.g. Boeing, Airbus and Gulfstream, the US Dept of Defense (DARPA, Air Force, Navy and the Army) Military and NASA.