Optimisation of aerodynamic performance of wig vehicle fuselage using blowing flow control technique

Wing in ground effect (WIG) vehicle is a type of vehicle that flies in the vicinity of the ground, taking advantage of the ground effect phenomenon. WIG vehicle can be categorised as a hybrid technology as it can operate close to the water or ground surface besides flying as fast as a conventional aircraft. Although WIG vehicle has superior advantages compared to either aircraft or marine craft, the usage of WIG is still limited because there are still some issue on its design. The stepped hull design of the WIG fuselage contribute to additional drag during flying condition because of flow separation at the stepped location. This aim of the study is to propose the use of active flow control in the form of blowing technique to improve the aerodynamic performance of WIG. The wind tunnel experiment was conducted with the blowing location located upstream from the step location. The distance of the blowing location with respect to the step height, h is 1.53h. The blowing velocity coefficients which is the ratio of blowing velocity and the free stream velocity used for the experiment are 0.98, 1.63 and 2.29. Six ground clearance which is the distance of the WIG from the ground with respect to the length of the fuselage has been tested. The ground clearance are in the range of 0.05 to 0.30. The results showed that the use of blowing at all ground clearance and blowing velocity coefficients led to the
reduction of drag compared to that of the baseline experiment. In terms of overall performance, the best combination was achieved at ground clearance of 0.05 and blowing velocity coefficient of 2.29, which resulted in 5% of drag reduction, 20% increased lift and 26% increase in lift-to-drag ratio. The data from this study indicate that the combination of ground effect and flow control can give a major improvement towards the performance of WIG vehicle.