This paper considers the effect of choice of actuator technology and associated power systems architecture on the mass cost and power consumption of implementing active flow control systems on civil transport aircraft. The research method is based on the use of a mass model that includes a mass due to systems hardware and a mass due to the system energy usage. An Airbus A320 aircraft wing is used as a case-study application. The mass model parameters are based on first-principle physical analysis of electric and pneumatic power systems combined with empirical data on system hardware from existing equipment suppliers. Flow control methods include direct fluidic, electromechanical-fluidic, and electrofluidic actuator technologies. The mass cost of electrical power distribution is shown to be considerably less than that for pneumatic systems; however, this advantage is reduced by the requirement for relatively heavy electrical power management and conversion systems. A tradeoff exists between system power efficiency and the system hardware mass required to achieve this efficiency. For short-duration operation the flow control solution is driven toward lighter but less power-efficient systems, whereas for longduration operation there is benefit in considering heavier but more efficient systems. It is estimated that a practical electromechanical-fluidic system for flow separation control may have a mass up to 40% of the slat mass for a leading-edge application and 5% of flap mass for a trailing-edge application.

This article documents the development of synthetic jet actuator array hardware to augment high-lift system effectiveness in a wind tunnel model. The study involved the design, manufacture and bench test of a synthetic jet actuator array based on an inclined actuator configuration to reduce volume installation requirements without a loss in jet velocity relative to a non-inclined baseline model; incorporation of proper synthetic jet actuator systems wiring and internal synthetic jet actuator chamber pressure-sensing for actuator health monitoring. The peak velocity obtained from the inclined synthetic jet actuator array was 100 m/s, which favourably compares to the baseline array ($90 m/s), while reducing the usable depth requirements by 50%. The final outcome of this study has been to apply the design lessons learned to develop a methodology for designing a synthetic jet actuator array with the constraints of using piezoelectricbased actuator technology for flow separation control applications.

An investigation into the behaviour of clustered synthetic jet Actuators for flow-control applications is described. Experiments have been undertaken with two small-scale synthetic jet actuators in a zero-pressure gradient boundary-layer, in order to investigate the effect of configuration yaw angle and relative input signal phase. Oil-flow visualisation and hotwire anemometry techniques were used, demonstrating that changes in the downstream flow structure could be observed. Compared to a streamwise configuration, in which a symmetrical counter-rotating vortex pair was produced by the synthetic jet-boundary-layer interaction, a broader asymmetric interaction was produced in a 15°yaw configuration. Streamwise velocity contour plots, illustrating the development of the interaction downstream, over four phase angles, were presented. Significant differences in the PSD analyses of downstream streamwise velocity time histories were found, suggesting that input signal phase could influence the stability and hence effectiveness of flow structures used in flow-control applications. Figure 1. Illustration of small-scale synthetic actuator zero pressure gradient turbulent boundary layer rig.Clockwise from left: Exploded view of one actuator; two such actuators mounted in the circular plate;Circular plate assembly mounted in the flat-plate aerofoil, and in the 0⋅5m × 0⋅5m Goldstein tunnel.

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