Active Flow Control Over a Wing Model Using Synthetic-Jet-Actuator Arrays
In this study, synthetic-jet-actuator (SJA) arrays were designed, implemented, and tested on a straight-wing model for flow separation control. First, the characteristics of a single SJA were determined. The jet velocity appears a peak between 400 and 500
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Abstract In this study, synthetic-jet-actuator (SJA) arrays were designed, implemented, and tested on a straight-wing model for flow separation control. First, the characteristics of a single SJA were determined. The jet velocity appears a peak between 400 and 500 Hz, which corresponds to the SJA’s Helmholtz resonance frequency. Second, two arrays of such SJAs were implemented at different chordwise locations on a straight-wing model. Force balance measurements and power spectrum analysis showed that both SJA arrays are able to effectively delay flow separation, with the front SJA array more effective than the rear one. For the front array, the improvement in CL and CD was 27.4 % and 19.6 %, respectively. Keywords Synthetic jet UAV
Synthetic-jet-actuator array Active flow control
1 Introduction Synthetic jet (SJ) technology has been proved to be a promising active flow control means in aeronautical applications, including flow separation control (Amitay and Glezer 2002; Zhong et al. 2007), mixing control (Pavlova et al. 2008), and turbulence control (Rathnasingham and Breuer 2003). As shown in Fig. 1, a typical synthetic jet actuator (SJA) consists of a cavity with an oscillatory diaphragm on one side and an orifice on another side. The oscillation of the diaphragm generates a succession of vortex structures that propagate away from the orifice, forming a so-called synthetic jet. Due to its well-known zero-net-mass-flux and compact H. Tang (&) P. Salunkhe J. Du Y. Wu School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore, Singapore e-mail: [email protected]
Y. Zhou et al. (eds.), Fluid-Structure-Sound Interactions and Control, Lecture Notes in Mechanical Engineering, DOI: 10.1007/978-3-642-40371-2_16, Springer-Verlag Berlin Heidelberg 2014
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Fig. 1 Schematic of a SJA
features, SJA can be easily implemented in arrays to achieve better flow control effects. As a study toward realizing active flow control for unmanned aerial vehicles (UAVs) by applying the SJ technology, the current investigation aims to design and deploy suitable SJA arrays to control the possible flow separation over a straight-wing model and hence enhance its aerodynamic performance. In addition, an experimental framework will be established for the investigation of the active flow control effectiveness and efficiency of SJA arrays on UAV wings.
2 Test Rig Setup and Instrumentation Experiments were carried out in a subsonic closed-loop wind tunnel at a speed of 10 m/s. The test section size of the wind tunnel is 0.8 m (W) 9 0.8 m (H) 9 2 m (L). The wing model used in this study is based on the low-speed LS(1)-0421MOD airfoil, with chord length c = 180 mm and span b = 255 mm. In the present study, a new design of piezoelectric-driven SJA is proposed as shown in Fig. 2. It consists of four 20-mm-diameter piezoelectric ceramic disks attached to its four sidewalls. An O-ring is placed right above the opening on its top for a leak-proof fit. Multiple such SJAs can be arraye
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