Flow Control Using Plasma Actuators
Previous research at the University of Kentucky in both the Fluid Mechanics Lab and the CFD Group has shown that plasma actuators can be used as an effective active flow control device. This research has been focused in boundary layer control and separated flow control.
Plasma actuators consist of two electrodes that are located on surface separated by a dielectric material. A high-voltage AC supplied to the electrodes causes the air in their vicinity to weakly ionize. The ionized air (plasma) in the presence of the electric field gradient produced by the electrodes, result in a body force vector acting on the external flow that can induce steady or unsteady velocity components as illustrated in the figure to the right.
The results from experimental investigations indicate that several parameters have to be taken into consideration for effective flow control. The important parameters are location of the actuators on the surface, orientation, size, and relative placement of the embedded and exposed electrodes, applied voltage, and frequency of the actuation.
Current research in the UK CFD Group deals with incorporating the model developed by Y.B. Suzen and P.G. Huang into the unstructured grid code UNCLE, a two/three dimensional unstructured grid based N-S solver. The effect of the plasma actuator is modeled as a body force vector tangent to the surface above the embedded electrode. This model has been verified through results obtained from its incorporation into GHOST, a two-dimensional structured grid based N-S solver. Some model details can be seen on the left.
Computational Efforts and Experimental Collaborations
At UK CFD we are currently developing a novel numerical simulation methodology and an optimization algorithm for active flow separation control applications using plasma actuators supported with experiments that are designed and conducted to provide high quality detailed measurements needed for development, testing, and validation of the numerical simulation techniques and modeling approach. For the experimental component of this research we are collaborating with Dr. Jamey Jacob and Arvind Santhanakrishnan.
The goals of computational efforts are:
(i)development of an accurate modeling approach to incorporate the effects of plasma actuator into CFD simulations,
(ii)development of a robust optimization technique based on genetic algorithm that will be coupled with CFD solver to the enable design, development, and testing of closed-loop flow separation control systems using plasma actuators,
(iii) testing and validation of the modeling approach and optimization algorithm against specifically designed experiments that will be conducted at University of Kentucky as well as a variety of available experiments from other sources.
Experimental component of the research provides high quality detailed measurements needed for development, testing, and validation of the numerical simulation techniques and modeling approach. The goals of the experimental efforts are:
(i) obtain a better understanding of the physics of plasma flow control and how plasma actuators can be integrated into flow control applications,
(ii) obtain data suitable for CFD code validation, and
(iii) implement the control scheme in a range of flows of interest to determine practical feasibility.
Current simulations of the S.-H. DBD plamsa actuator model are underway for applications extending beyond that of the linear DBD plasma actuator. These simulations include the study of linear plasma synthetic jet actuators (L-PSJAs). The current focus is to validate the model against different experimental configurations of this device for quiescent and crossflow. This includes comparisons of jet width, peak velocity loss, wall effects, and cross flow velocity profiles. A paper will be presented at the 46th AIAA Aerospace Meeting and Exhibit displaying results relative to simulations of L-PSJAs in these different configurations.
A demostration of an unsteady simulation of a L-PSJA in quiescent flow with a pulsing frequency of 10Hz can be found in the figures below. In these figures, the peak velocity near the actuator interface corresponds to the formation of the vortex pairs near the actuator; which agrees with experimental observations.
Related Publications:
-
"Numerical Simulations of Plasma Based Flow Control Applications", Y.B. Suzen, P.G. Huang, J.D. Jacob, D.E. Ashpis, AIAA Paper 2005-4633, 35th AIAA Fluid Dynamics Conference, June 2005, Toronto.
-
"Simulations of Flow Separation Control using Plasma Actuators", Y.B. Suzen, P.G. Huang AIAA Paper 2006-877, 44th AIAA Aerospace Sciences Meeting & Exhibit, Reno, NV, Jan. 2006.
-
"Unstructured Grid Simulations of Plasma Actuator Models", R.P. LeBeau, D.A. Reasor, Y.B. Suzen, AIAA Paper 2007-3973 , 37th AIAA Fluid Dynamics Conference, Miami, FL, June 2007.
- "Unstructured Numerical Simulation of Experimental Plasma Actuator Flows", R.P. LeBeau, D.A. Reasor, A. Santhanakrishnan, submitted to the 46th AIAA Aerospace Sciences Meeting and Exhibit, Reno, NV, Jan 2008.