An Analysis of Ground Effects on Aerodynamic Characteristics of Aerofoils Using Boundary Layer Approximation

Abstract

Investigation of a new high-speed zero-emission transportation “Aerotrain” is proceeded mainly in Tohoku University and Miyazaki University. Since the aerotrain utilizes the ground effect, researches of the aerofoil section which can harnesses the ground effect effectively are important. The aerotrain moves along U-shaped guide way which has a ground and side walls, so it has many viscous interference elements. In an analysis of ground effects on aerodynamic characteristics of aerofoils, it must be considered boundary layers on the aerofoil surface. At first, velocity distributions on surfaces of aerofoils in potential flows are computed using the vortex method, then the momentum integration equations of boundary layer is solved with experimental formulas. This procedure has following advantages : modifications of aerofoil section are easy because it is not necessary to make complicated computational grids, a boundary layer transition and separation can be predicted using empirical procedures. The aerodynamic characteristics of four kinds of aerofoil sections is investigated to clarify the relation between aerofoil sections and ground effects. Computational results are compared with experiments results by the towing wind tunnel to verify computational precisions. In addition, aerofoil characteristics at actually cruise speed are analyzed.