We conducted large eddy simulations of the control of separated flow over an airfoil using body forces and discuss the role of a three-dimensional vortex structure in separation control. Two types of cases are examined: (1) the body force is distributed in a spanwise uniform layout and (2) the body force is distributed in a spanwise intermittent layout, with three-dimensional vortices being expected to be generated in the latter cases. The flow fields in the latter cases have a shorter separation bubble than those in the former cases although the total momentum of the body force in the latter cases is the same as or half of the former cases. In the flow fields of the latter type, the three-dimensional vortices, which are not observed in the former cases, are generated by the body force downstream of the body force distributed. Thus, three-dimensional vortices are considered to be effective in controlling the separated flow. 1. Introduction Recently, the dielectric barrier discharge (DBD) plasma actuator [1] (hereafter, “plasma actuator”)—a small active flow control device—has been receiving a lot of attention because it is superior to conventional devices with respect to reactivity, a comparatively simple structure, and smaller energy consumption. The plasma actuator can probably find applications in unmanned air vehicles (UAVs) [2] and turbine blades [3, 4]. In this paper, we investigate the potential applications of a plasma actuator in separation control. Figure 1 shows a schematic diagram of a plasma actuator. As shown, a plasma actuator consists of two electrodes and a dielectric. A plasma actuator generates plasma by means of dielectric barrier discharge in the area between the exposed electrode and the dielectric when a high alternating current (AC) voltage is applied to the electrodes, inducing flow. Figure 1: Configuration of plasma actuator. Many experiments and numerical simulations are conducted in this study, and their results show the applicability of a plasma actuator for use in separation control. In particular, a lot of studies are conducted on the input AC parameters (e.g., voltage, frequency, and waveform) [5, 6]. With respect to the waveform shown in Figure 2, it has been found that using an unsteady input voltage, or “ burst wave,” gives a better separation control capability [5, 7, 8]. The nondimensional burst wave frequency is set between 1 and 10 in these studies. Figure 2: Burst wave image. Research conducted to clarify the mechanism of separation control is mainly performed by means of numerical simulations. Asada and Fujii
References
[1]
T. C. Corke, M. L. Post, and D. M. Orlov, “SDBD plasma enhanced aerodynamics: concepts, optimization and applications,” Progress in Aerospace Sciences, vol. 43, no. 7-8, pp. 193–217, 2007.
[2]
M. P. Patel, T. T. Ng, S. Vasudevan, T. C. Corke, and C. He, “Plasma actuators for hingeless aerodynamic control of an unmanned air vehicle,” Journal of Aircraft, vol. 44, no. 4, pp. 1264–1274, 2007.
[3]
D. P. Rizzetta and M. R. Visbal, “Numerical investigation of plasma-based flow control for a transitional highly-loaded low-pressure turbine,” in Proceedings of the 45th AIAA Aerospace Sciences Meeting, vol. 16, pp. 11366–11388, 2007, AIAA 2007-938.
[4]
D. K. Van Ness, T. C. Corke, and S. C. Morris, “Tip clearance flow control in a linear turbine cascade using plasma actuation,” in Proceedings of the 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, p. 300, January 2009, AIAA 2009-300.
[5]
A. A. Sidorenko, B. Y. Zanin, B. V. Postnikov et al., “Pulsed discharge actuators for rectangular wing separation control,” in Proceedings of the 45th AIAA Aerospace Sciences Meeting, pp. 11422–11432, January 2007, AIAA 2007-941.
[6]
D. Tsubakino, Y. Tanaka, and K. Fujii, “Effective layout of plasma actuators for a flow separation control on a wing,” in Proceedings of the 45th AIAA Aerospace Sciences Meeting, vol. 9, pp. 5695–5704, 2007, AIAA 2007-474.
[7]
B. Goksel, D. Greenblatt, I. Rechenberg, C. N. Nayeri, and C. O. Paschereit, “Steady and unsteady plasma wall jets for separation and circulation control,” in Proceedings of the 3rd AIAA Flow Control Conference, pp. 1621–1635, San Francisco, Calif, USA, June 2006, AIAA 2006-3686.
[8]
M. P. Patel, T. T. Ng, S. Vasudevan et al., “Scaling effects of an aerodynamic plasma actuator,” in Proceedings of the 45th AIAA Aerospace Sciences Meeting, vol. 11, pp. 7654–7679, 2007, AIAA 2007-635.
[9]
K. Asada and K. Fujii, “Computational analysis of unsteady flow-field induced by plasma actuator in burst mode,” in Proceedings of The 5th Flow Control Conference, Chicago, Ill, USA, June 2010, AIAA 2010-5090.
[10]
J. Poggie, C. P. Tilmann, P. M. Flick et al., “Closed-loop stall control on a morphing airfoil using hot-film sensors and DBD actuators,” in Proceedings of The 48th AIAA Aerospace Sciences Meeting, Orlando, Fla, USA, January 2010, AIAA 2010-547.
[11]
D. P. Rizzetta and M. R. Visbal, “Numerical investigation of plasma-based control for low-reynolds number airfoil flows,” in Proceedings of the 5th Flow Control Conference, June 2010, AIAA 2010-4255.
[12]
K. Asada, Y. Ninomiya, A. Oyama, and K. Fujii, “Airfoil flow experiment on the duty cycle of DBD plasma actuator,” in Proceedings of The 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Orlando, Fla, USA, January 2009, AIAA 2009-0531.
[13]
Y. B. Suzen and P. G. Huang, “Simulations of flow separation control using plasma actuators,” in Proceedings of The 44th AIAA Aerospace Sciences Meeting, pp. 10456–10464, January 2006, AIAA 2006-877.
[14]
C. L. Enloe, M. G. McHarg, G. I. Font, and T. E. McLaughlin, “Plasma-induced force and self-induced drag in the dielectric barrier discharge aerodynamic plasma actuator,” in Proceedings of The 47th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, Orlando, Fla, USA, January 2009, AIAA 2009-1622.
[15]
K. Fujii, “Developing an accurate and efficient method for compressible flow simulations-example of CFD in aeronautics,” in Proceedings of the 5th International Conference on Numerical Ship Hydrodynamics, 1990.
[16]
S. Obayashi, K. Matsushima, K. Fujii, and K. Kuwahara, “Improvements in efficiency and reliability for navier-stokes computations using the LU-ADI factorization algorithm,” in Proceedings of the 24th AIAA Aerospace Sciences Meeting, New York, NY, USA, 1986, AIAA 86-0513.
[17]
S. K. Lele, “Compact finite difference schemes with spectral-like resolution,” Journal of Computational Physics, vol. 103, no. 1, pp. 16–42, 1992.
[18]
M. R. Visbal and D. V. Gaitonde, “Computation of aeroacoustic fields on general geometries using compact differencing and filtering schemes,” in Proceedings of The American Institute of Aeronautics and Astronautics, 1999, AIAA 1999-3706.
[19]
D. V. Gaitonde and M. R. Visbal, “Pade-type higher-order boundary filters for the navier-stokes equations,” AIAA Journal, vol. 38, pp. 2103–2112, 2000.
[20]
H. Nishida and T. Nonomura, “ADI-SGS scheme on ideal magnetohydrodynamics,” Journal of Computational Physics, vol. 228, no. 9, pp. 3182–3188, 2009.
[21]
M. R. Visbal and D. P. Rizzetta, “Large-eddy simulation on general geometries using compact differencing and filtering schemes,” in Proceedings of The American Institute of Aeronautics and Astronautics, 2002, AIAA 2002-288.
[22]
K. Fujii, “Unified zonal method based on the fortified solution algorithm,” Journal of Computational Physics, vol. 118, no. 1, pp. 92–108, 1995.
