An Experimental Investigation of Perturbations on Vortex Breakdown over Delta Wings

An experimental investigation on vortex breakdown on delta wings at high angles of attack is presented. As suggested by previous works, perturbations are used to change the platform of the delta wings to reduce the detrimental effects of vortex breakdown brought about by the Self-Induction Theory. Different patterns of ‘round’ perturbations are tested to obtain the favourable lift and drag characteristics for each wing. With the best pattern identified later, optimization of the shape of perturbation is explored to further improve the results. ‘Teardrop’ and ‘diamond’ perturbations are introduced as basis of comparison. Force measurements were conducted over a range of α = 0 to 40° to justify the concept of surface shaping and evaluate its effectiveness. Dye flow visualization were used to obtain sectional views of the leading-edge vortices as they break down for a series of delta wings having sweep angles of 60°, 65° and 70°. The wings are tested constantly at a low speed of U∞ = 0.05 m/s in a water tunnel facility. A combination of side and plan views provides information on the three-dimensional nature of the vortex structure before, during and after breakdown. Details of the flow at α =15° for every wing are identified in still photographs while the dynamic characteristics of the breakdown process are examined from recorded high-speed movies. The force measurement supported by the flow visualization shows that certain combinations of perturbations indeed provide encouraging results. For wings with perturbations, generally, the vortex structure transforms from a linear structure to a wavy or “kink” structure which effectively delay or even suppress vortex breakdown. Various results have shown an increase of approximately 10% in lift characteristics and delay of stall angle for certain scenarios. The best results have been for the 60° wing where the ‘teardrop’ bulge in a mild perturbation pattern managed to improve lift characteristics by about 15% over the whole range of angle of attack for the tests. Results for the 65° wing and 70° wing are generally positive with the ‘teardrop’ perturbation again providing the best results, however with existence of discrepancies over certain angles of attack

Experimental study of oscillating SD8020 foil for propulsion

The thrust producing performance and efficiency of an SD8020 oscillating foil with a symmetrical saw-tooth angle of attack pitching profile was studied through force and torque measurements, as well as dye flow visualization, in the water tunnel at low Reynolds number of 13,000-16,000. The propulsive efficiency and thrust coefficient of the pitching foil were determined as a function of the Strouhal number, pitch amplitude and angular frequency. A propulsive efficiency of 30% was obtained experimentally at low Strouhal numbers. The flow visualization has revealed different wake patterns at various Strouhal numbers and can be classified into three regimes – a drag wake, a transition wake and a thrust wake. The drag wake consists of a combination of a regular Kármán street and an array of ‘primary’ stop-start vortices, whereas the thrust wake consists of a reverse Kármán vortex street, commonly observed in swimming fish. The transition wake regime, which occurs at approximately 0.2 < St < 0.5, is interpreted as a momentum balanced wake, where the thrust developed by the foil approximately balances its produced drag. This wake was observed to either consist of an inclined vortex street, or a paired vortex pattern. Based on the force and efficiency data collected, increasing pitch amplitude and angular frequency was associated with a decrease in propulsive efficiency and an increase in thrust forces produced. A high efficiency value of 0.3, accompanied by a thrust coefficient of order one is found at a low pitch amplitude of 10°, angular frequency of 0.79 rad/s and Strouhal number of 0.05. This presented the best conditions for thrust production observed at low Strouhal and Reynolds numbers

Field Test Validations of Vision-based Multi-camera Multi-drone Tracking and 3D Localizing with Concurrent Camera Pose Estimation

10.1109/ICCRE51898.2021.94356542021 6th International Conference on Control and Robotics Engineering (ICCRE)139-14

Hybrid motion-based object detection for detecting and tracking of small and fast moving drones

10.1109/ICUAS48674.2020.92139122020 International Conference on Unmanned Aircraft Systems (ICUAS)615-62

Near-Parallel Binocular-Like Camera Pair for Multi-Drone Detection and 3D Localization

10.1109/ICARCV50220.2020.93054852020 16th International Conference on Control, Automation, Robotics and Vision (ICARCV)204-21

Design and development of UGS flapping wing MAVs

This paper describes the design, build and fly University of Glasgow Singapore (UGS) flapping wing MAVs using fabrication method such as laser cutting and Rapid Prototyping. The first prototype was made from acrylic using a laser cutting machine. The material was strong however it was brittle. The wings were made up of carbon rods and kite material Ripstop. First test showed that the wings were too heavy for the mechanism to work. The second and final prototype was a smaller single gear crank design which was fabricated using a 3D printer. Initial test proved that the prototype 2 could withstand the high frequency flapping required for lift. The second test performed was to tether it on a string. At high frequency the prototype 2 was able to move in a circular motion

Drone detection using YOLOv3 with transfer learning on NVIDIA Jetson TX2

10.1109/ICA-SYMP50206.2021.93584492021 Second International Symposium on Instrumentation, Control, Artificial Intelligence, and Robotics (ICA-SYMP

Trajectory Prediction Path Planning for an Object Intercepting UAV with a Mounted Depth Camera

10.23919/ICCAS52745.2021.96499122021 21st International Conference on Control, Automation and Systems (ICCAS)2021-October703-70

Enabling Continuous Drone Tracking across Translational Scene Transitions through Frame-Stitching

10.1109/ICA-SYMP50206.2021.93584442021 Second International Symposium on Instrumentation, Control, Artificial Intelligence, and Robotics (ICA-SYMP

Multiple Aerial Targets Re-Identification by 2D-and 3D-Kinematics-Based Matching

10.3390/jimaging8020026Journal of Imaging8226-2