Separation control by means of oriented DBD plasma actuators: an experimental analysis in a wind tunnel

This thesis provides an experimental analysis of the effectiveness of oriented DBD plasma actuators over a NACA 0015 airfoil at low Reynolds numbers. Tests were performed in partnership with the Department of Electrical Engineering of Bologna University, in the wind tunnel of the Applied Aerodynamics Laboratory of Aerospace Engineering faculty. Lift coefficient measurements were carried out in order to verify how an oriented plasma jet succeeds in prevent boundary layer separation. Both actuators’ chord wise position and plasma jet orientation angle have been investigated to examine which configurations lead to the best results. A particular attention has been paid also to the analysis of results in steady and unsteady plasma actuation. Questa tesi offre un’analisi sperimentale sull’efficacia di attuatori al plasma orientabili, basati su una tecnologia DBD, installati su un profilo alare NACA 0015, a bassi numeri di Reynolds. Le prove sono state condotte in collaborazione con il Dipartimento di Ingegneria Elettrica dell’Università di Bologna, nella galleria del vento del Laboratorio di Aerodinamica Applicata della Facoltà di Ingegneria Aerospaziale di Forlì. Per verificare come un getto orientabile di plasma riesca a prevenire la separazione dello strato limite, sono state eseguite misure sul coefficiente di portanza. Sono state indagate sia la posizione degli attuatori lungo la corda che l’angolo con cui è orientato il getto di plasma, per vedere quali configurazioni conducono ai migliori risultati. Una particolare attenzione è stata riservata all’analisi dei risultati ottenuti con plasma continuo e pulsato.

Modeling and analysis of a zipping elastomeric actuator

This thesis introduces and analyzes a dielectric elastomer actuator (DEA) working in zipping mode. Electrostatic zipping is a very familiar actuation principle used in silicon micro-electro-mechanical systems. With lower voltage supply, electrostatic zipping can provide great performance for forces and displacements of an elastic membrane. Applying this principle to dielectric elastomers, the softness of the material will provide better compliance compared to silicon materials. After the presentation of an analytical model, this thesis investigates how system geometry and elastomer pre-tensioning affect system response. Results highlight how a proper selection of system parameters makes it possible to improve system regulation and reduce operating voltage requirements. Potential applications of zipping DEAs are for microfluidic control and electro-forming.