Effect of Local DBD Plasma Actuation on Transition in a Laminar Separation Bubble
This work examines the effect of local active flow control on stability and transition in a laminar separation bubble. Experiments are performed in a wind tunnel facility on a NACA 0012 airfoil at a chord Reynolds number of 130 000 and an angle of attack of 2 degrees. Controlled disturbances are introduced upstream of a laminar separation bubble forming on the suction side of the airfoil using a surface-mounted Dielectric Barrier Discharge plasma actuator. Time-resolved two-component Particle Image Velocimetry is used to characterise the flow field. The effect of frequency and amplitude of plasma excitation on flow development is examined. The introduction of artificial harmonic disturbances leads to significant changes in separation bubble topology and the characteristics of coherent structures formed in the aft portion of the bubble. The development of the bubble demonstrates strong dependence on the actuation frequency and amplitude, revealing the dominant role of incoming disturbances in the transition scenario. Statistical, topological and linear stability theory analysis demonstrate that significant mean flow deformation produced by controlled disturbances leads to notable changes in stability characteristics compared to those in the unforced baseline case. The findings provide a new outlook on the role of controlled disturbances in separated shear layer transition and instruct the development of effective flow control strategies.
KeywordsLaminar separation bubble Airfoil Boundary layer separation Separated shear layer Laminar-to-turbulent transition DBD plasma actuator Flow control
- 1.Carmichael, B.H.: Low reynolds number airfoil survey NASA CR 165803 (1981)Google Scholar
- 2.Gaster, M.: The Structure and Behaviour of Laminar Separation Bubbles Reports and Memoranda, vol. 3595. Aeronautical Research Council, London (1967)Google Scholar
- 22.Ol, M.V., Mcauliffe, B.R., Hanff, E.S., Scholz, U., Kähler, C.: Comparison of laminar separation bubble measurements on a low Reynolds number airfoil in three facilities. In: 35th AIAA Fluid Dynamics Conference and Exhibit, June, Toronto (2005)Google Scholar
- 39.Van Ingen, J., Kotsonis, M.: A Two-Parameter Method for En Transition Prediction. In: 6th AIAA Theoretical Fluid Mechanics Conference (2011)Google Scholar
- 40.Drazin, P.G., Reid, W.H.: Hydrodynamic stability (1981)Google Scholar