. The three-dimensional flow organization past a micro-ramp in a supersonic boundary layer. Physics of Fluids, 24(5), 055105. doi: 10.1063/1.4711372 This is the accepted version of the paper.This version of the publication may differ from the final published version. The three-dimensional instantaneous flow organization in the near wake of a micro-ramp interacting with a Mach 2.0 supersonic turbulent boundary layer is studied using Permanent

In cognitive radio networks, the unlicensed users can utilize the unoccupied licensed spectrum opportunistically. In this paper, we propose a joint power and end-to-end rate control algorithm considering restricting the interference to licensed users. By duality theory, the optimal resource allocation solution is given for the unlicensed users while satisfying the interference temperature limits. An asynchronous algorithm is proposed to be implemented in practical networks. Finally, we give a discussion to the proposed algorithm's performance on fairness. Numerical results show that the proposed algorithm can limit the interference to licensed user under a predefined threshold while maintaining a satisfied data rate fairly. 1

This is the accepted version of the paper.This version of the publication may differ from the final published version. The wakes resulting from micro-ramps immersed in a supersonic turbulent boundary layer at Ma=2.0 are investigated by means of particle image velocimetry (PIV). Two micro-ramps are investigated with height of 60% and 80% of the undisturbed boundary layer, respectively. The measurement domain is Permanent repository link

To solve the low efficiency of plasma synthetic jet actuator (PSJA), a multichannel discharge technique based on the concept of voltage relay is put forward and a new multi-electrode plasma synthetic jet actuator (ME-PSJA) is designed. Experiment shows the multichannel discharge technique can enlarge the discharge channel distance by multiplying the discharge channel number without increasing the input voltage. With a 1 nF discharge capacitor, the discharge efficiency of three channels discharge increases 135% compared with standard one channel discharge. When the discharge capacitor increases to 0.3 μF, a four discharge channels still improves the discharge efficiency 119 % as well. Schlieren flow visualization confirms that ME-PSJA also outperforms the 2-electrode PSJA in terms of jet velocity and duration time, both are increased by about 50%.

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This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link Abstract:The plasma synthetic jet actuator (PSJA) is a flow control device capable of generating high speed pulsed jet. However, the performance of conventional PSJA is restricted by low discharge efficiency and small control area, because one power supply only drives one electrode couple. The present work is to propose a new concept of multichannel discharge plasma synthetic jet actuator (MD-PSJA), which is driven by single power supply. The new MD-PSJA has two types, namely the multi-electrode PSJA and the multi-PSJA array. These two types of MD-PSJA are examined experimentally. The multi-electrode PSJA containing 11-electrode PSJA is first studied. Comparison with standard 2-electrode PSJA reveals that the discharge efficiency and jet velocity increase 200% and 47% respectively under the same input energy and discharge voltage. The multi-PSJA array is later evaluated. One power supply is found to be able to drive an array of 12 PSJAs, resulting in 6 times affected area and 64% jet velocity of a conventional PSJA. The proposed MD-PSJA is finally concluded an improved active flow control actuator in high speed applications.

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link

This is the accepted version of the paper.This version of the publication may differ from the final published version. Permanent repository link: http://openaccess.city.ac.uk/20337/ Link to published version: http://dx. ABSTRACTAn array of 16 surface arc plasma actuators (SAPAs) is employed to control the shock wave boundary layer interaction (SWBLI) at a 26° compression ramp in a Mach 2.0 flow. A new electrical circuit is used to actuate all the 16 SAPAs. The electrical measurement reveals significant augmentation in peak current (200 A) and energy deposition of 1.05 J, which is the nominal characteristics of the setup. The SAPA array is later applied for SWBLI control. The actuator array is placed upstream of the SWBLI and operates at four different frequencies, namely 500 Hz, 1 kHz, 2 kHz and 5 kHz. In the wind tunnel experiment, high-speed schlieren at 25,000 frames per second is used for flow visualization. The shock wave system is modified significantly by the controlling gas blobs (CGBs) generated by SAPAs. The foot portion of the separation shock wave disappears and the oblique shock wave bifurcates when the CGBs passes through the interaction region. The shock weakening effect is further verified through the rms of the schlieren intensity of the same phase.Keywords: shock wave boundary layer interaction, surface arc plasma actuator, supersonic flow control, active flow control a) Electronic mail: wuyun1223@126.com.