By controlling the flow on air wings, one may decrease dramatically aircraft fuel consumption and/or noise. It has been proved that the separation can be managed by blowing oscillatory air jets in the boundary layer through submillimetric holes situated on the surface near the separation area. Performance improvement of the next generation planes (lift enhancement, drag reduction,...) pushes plane designers to investigate MEMS solutions in order to provide active control of the air flow surrounding wings and compressor blades. In order to answer the needs of the aeronautical industry, two small sized, high flow rate, dynamically actuated microvalve prototypes were designed, fabricated and characterized. A first prototype consists in a silicon channel, alternatively pinched by a Poly(dimethilsiloxane) (PDMS) polymer membrane. Actuation is provided by coupling an inductive driving coil and a NdFeB permanent magnet situated on the PDMS flexible membrane, yielding the valve closure. A second prototype, dedicated to higher frequency actuation, consists in a resonating silicon cantilever, acting as a deflector on the internal fluid flow, alternatively addressing it to the output hole and to a recycling output. The cantilever is coated with a nanostructured (TbCo/FeCo)n magnetostrictive film, driving it at its resonance frequencies. Moreover, Spin Reorientation Transition (SRT) is induced in the film in order to benefit from a dramatic increase of the magnetoelastic sensitivity. In this case, two micro coils are sufficient for dynamic driving of the microsystem. Characterization of both actuators is presented in this paper : impermeability in closed mode, jet geometry in open mode (Schlieren imagery) ; outlet jet speed (hot wire anemometry), mechanical deflection and vibration results are also presented.
Magnetically actuated microvalves for active flow control
Magnetisch betriebene Mikroventile für die aktive Mengendurchflussregelung
2006
4 Seiten, 7 Bilder, 8 Quellen
Aufsatz (Konferenz)
Englisch
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