Parametric study and modelling of the dielectric barrier discharge plasma actuator for flow control

Abstract

Dielectric Barrier Discharge (DBD) plasma actuators are widely studied in different applications such as flow control, de-icing, surface coating or surface cleansing. For instance, in their flow control use, flow reattachment can be achieved, or boundary layer control can be performed. DBD actuators can be used in different shapes or with different electric signals, which have different effects on the flow. However, the flow control abilities of the DBD are limited to low Reynolds numbers, with a lack of knowledge on the optimum design or a mathematical model to predict the optimum design of a DBD. Consequently, the following study focuses on the parametric investigation of the DBD actuator, in order to determine the relative significance of its design parameters, based on their effects on the momentum induced by the DBD in the airflow and on its electrical power consumption. Due to its lower power consumption and its ability to be used in different flow control cases, the AC driven DBD is focused on in the study. The momentum induced by DBD actuators is evaluated through the thrust generated devices, and the thrust over power ratio (or force efficiency) is used as a surrogate of the efficiency. A test rig has been created, in order to measure the small thrust induced by 10 cm wide DBDs. The test rig measures the thrust via a lever that amplifies the force generated by a DBD. The assessment of the new test rig demonstrates that its measurements of the thrust and power are accurate and repeatable. Nine design parameters of the DBD have been analysed with a Design of Experiment, using the data measured by the test rig. A fractional factorial design was employed with a resolution of IV, and a confidence level of 95%. The results show that mainly the electric parameters and the geometries of the dielectric and of the air electrode influence the thrust, power and force efficiency of DBDs. Firstly, a high voltage yields the greater thrust and force efficiency. Secondly, a high AC frequency results in a greater thrust but a smaller force efficiency. Thirdly, a short distance between the electrodes is need to reach a higher thrust and force efficiency. Finally, a thin and narrow air exposed electrode generates a greater thrust. The ranking of the parameters allows general guidelines to be drawn, that can be followed to achieve the best flow control performance of particular DBDs. The DOE derives models that can approximate the power consumption and force efficiency. The product of these two models provide reasonable estimates of the thrust generation, with a maximum inaccuracy of 0.9 mN/m. These models can be used to estimate the most suitable DBD design for a particular application. Then, the provided guidelines can be followed to achieve the highest force efficiency or thrust generation of this DBD.

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ORCID for Sylvain Grosse: orcid.org/0000-0002-0365-1357

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