| Summary: | The flow above the upper surface of delta wing is dominated by a very complicated and unresolved vortex structure. This study investigates the effects of the propeller advance ratio on the vortex properties and vortex breakdown above a generic 55° sharp-edged non-slender delta wing UAV model. The experiments were conducted in a closed circuit UTM-LST wind tunnel at the wind speeds of 15 m/s, 20 m/s and 25 m/s respectively at various angles of attack ranging from 0° to 18°. In this project, the propeller is installed in front of the UAV model. Two measurement techniques were employed on the model; steady balance measurement and surface pressure measurement. The experimental data highlight the effects of propeller advance ratio on lift, drag, pitching moment and vortex characteristics of the UAV model. The results from the steady balance data showed that the propeller advance ratio has increased the lift and drag coefficients respectively. The results from the surface pressure measurement have showed that the propeller advance ratio influences the development of the primary vortex above the delta-winged model. The main observation from this study was the vortex breakdown developed in the trailing edge has been much influenced by the propeller advance ratio.
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