Effect of Ground Proximity on Aerodynamic Characteristics of NACA 4412 Airfoil.

Ground effect plays a vital role in modulating the flow behavior over any streamlined body. The most widely used wing-in ground effect (WIG) aircrafts and seaplanes utilize this phenomenon in order to enhance the aerodynamic performance during the landing and take-off phases of flight. This paper investigates the aerodynamics of ground effect on a NACA 4412 rectangular wing without end plates. The experiment was conducted in a low-speed wind tunnel at Re=2×105 for the ground clearance of 1 and 0.5 of the chord, measured from the maximum thickness position on the airfoil. The pressure distribution over the chord length was recorded for α=3° and 6° to verify the effect of ground clearance during takeoffs. The results have shown to be in good accordance with the literature, as the coefficient of lift augmented with increase in ground proximity and the induced drag was minimized.

Impact of the ground clearance on the annual energy production and tower cost of an offshore wind turbine

This article analyzes the impact of the ground clearance on the Annual Energy Production (AEP) and tower cost of a 20 MW offshore wind turbine. In addition, the influence of the rated wind speed on the analysis result will be considered. The AEP is computed by considering wind speed variation over the swept area of the rotor blades. The tapered tubular steel tower is considered for mass and cost calculation. The tower is considered as a fixed-free cantilever beam with concentrated mass at the free end. The analysis shows that the ground clearance only has a minor impact on the AEP but it has a remarkable impact on the tower mass. Specifically, when the ground clearance reaches 50 meters, the AEP only increases by roughly 3% while tower mass is nearly doubled compared to the case with no ground clearance. The results also reveal the significant impact of the rated speed on both the AEP and tower mass.

Effects of Aerodynamic downforce on Vehicle Control and Stability

This paper deals with the analysis of vehicle handling with the variation of downforce. A vehicle with aero package were taken and the values of aerodynamic downforce and front downforce distribution for different front and rear ride heights were taken. This was followed by the generation of yaw moment diagram at original ground clearance of 30mm. Aero map data were collected and individual yaw moment diagrams were collected from which vehicle handling parameters are noted. Different contour plots were made to understand the variation of vehicle handling with different ride heights (aerodynamics downforce and downforce distribution). The paper concludes with the sensitivity study where effects of aerodynamic downforce were recorded on vehicle control and stability.