A piezo-actuated closed loop MEMS system for active delay of transition

Haller, Daniel; Hempel, Jochen; Paetzold, A.; Losse, N.; Peltzer, Inken; Nitsche, W.; King, Rudibert; Woias, Peter

doi:10.1109/sensor.2009.5285807

Cited by 8 publications

(3 citation statements)

References 4 publications

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“…The basic suitability of PPC actuators combined with a silicone membrane for active cancellation has already been successfully proven in previous experiments (Haller et al, 2009). Using one single PPC actuator and a 26 Â 6 mm 2 large membrane, in combination with the same sensors and control, enabled a dampening of TS waves of 42%.…”

Section: Wind Tunnel Experimentsmentioning

confidence: 79%

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Piezo-Polymer-Composite Unimorph Actuators for Active Cancellation of Flow Instabilities Across Airfoils

Haller

Paetzold

Losse

et al. 2011

Journal of Intelligent Material Systems and Structures

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This article presents a smart device for active cancellation of flow instabilities. An array of two piezo unimorph actuators fabricated in piezo-polymer-composite technology is combined with a thin silicone membrane to mimic a movable wall with a closed surface. By locally displacing the thin membrane, a surface wave is generated that interferes with naturally occurring flow instabilities within the boundary layer of an airfoil. Using flow sensors and an intelligent control enables a destructive interference and therefore, an attenuation of natural flow instabilities. This leads to a delay of transition. The boundary layer remains laminar which means drag is reduced. Within the next pages, the setup of the device with actuators, membrane, sensors, and control is introduced. The main focus of this article is on actuator design, modeling, and implementation for wind tunnel experiments. Results of actuator characterization are presented. The non-linear behavior of the piezoactuator (harmonic distortions and impact of high electric fields) is investigated in detail. This study concludes with the results obtained in wind tunnel experiments which prove the functionality of the presented approach. A maximal attenuation of natural occurring flow instabilities of 80% is achieved.

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Section: Wind Tunnel Experimentsmentioning

confidence: 79%

“…As a first step, a prototype, consisting of only one actuator, was developed and tested (Haller et al, 2009). The basic suitability of piezo-polymer-composite (PPC) actuators combined with the flexible silicone membrane has been proven with this prototype.…”

Section: Introductionmentioning

confidence: 99%

Piezo-Polymer-Composite Unimorph Actuators for Active Cancellation of Flow Instabilities Across Airfoils

Haller

Paetzold

Losse

et al. 2011

Journal of Intelligent Material Systems and Structures

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“…In experiments, the extension from one locally fixed sensor-actuator system to a sequence of five streamwise cascaded actuator elements allows for an extended delay in transition, because reamplification of TS waves is delayed across a wider area ( figure 13). The five-element 'cymbal' actuator applied was developed in collaboration with the Department of Microsystems Engineering (IMTEK) at the University of Freiburg [22].…”

Section: (C) Low-speed Wind-tunnel Experiments With An 'Active-wall' mentioning

confidence: 99%

On active control of laminar–turbulent transition on two-dimensional wings

Erdmann

Pätzold

Engert

et al. 2011

Phil. Trans. R. Soc. A.

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This paper gives an overview of drag reduction on aerofoils by means of active control of Tollmien-Schlichting (TS) waves. Wind-tunnel experiments at Mach numbers of up to M x = 0.42 and model Reynolds numbers of up to Re c = 2 × 10 6 , as well as in-flight experiments on a wing glove at Mach numbers of M < 0.1 and at a Reynolds number of Re c = 2.4 × 10 6 , are presented. Surface hot wires were used to detect the linearly growing TS waves in the transitional boundary layer. Different types of voice-coil-and piezo-driven membrane actuators, as well as active-wall actuators, located between the reference and error sensors, were demonstrated to be effective in introducing counterwaves into the boundary layer to cancel the travelling TS waves. A control algorithm based on the filtered-x least mean square (FxLMS) approach was employed for inflight and high-speed wind-tunnel experiments. A model-predictive control algorithm was tested in low-speed experiments on an active-wall actuator system. For the in-flight experiments, a reduction of up to 12 dB (75% TS amplitude) was accomplished in the TS frequency range between 200 and 600 Hz. A significant reduction of up to 20 dB (90% TS amplitude) in the flow disturbance amplitude was achieved in high-speed wind-tunnel experiments in the fundamental TS frequency range between 3 and 8 kHz. A downstream shift of the laminar-turbulent transition of up to seven TS wavelengths is presented. The cascaded sensor-actuator arrangement given by Sturzebecher & Nitsche in 2003 for lowspeed wind-tunnel experiments was able to shift the transition Dx = 240 mm (18% x/c) downstream by a TS amplitude reduction of 96 per cent (30 dB). By using an active-wall actuator, which is much shorter than the cascaded system, a transition delay of seven TS wavelengths (16 dB TS amplitude reduction) was reached.

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