A numerical investigation on aerodynamic characteristics of an air-cushion vehicle

• Internal and external flows inside and around an air-cushion vehicle (ACV) have been studied.
• Lift and drag coefficients as well as a qualitative description of the flow field are presented.
• Aerodynamic characteristics of an ACV are compared with those of a road vehicle (car).
• Wake structures of an ACV and that of a land vehicle exhibit significant differences.
• Factors affecting lift and drag are discussed in detail.

This paper describes a numerical study of incompressible, steady, three-dimensional turbulent air flow inside and around a simplified air-cushion vehicle (ACV) model. Two distinct cases have been studied separately regarding type of motion of the ACV; the first case is sole hovering with no forward motion where only flow through the ACV was considered, the second case is both hovering and translational motions for which the external flow around the vehicle body becomes of interest. It is assumed that both motions take place on land (above a solid plane). A hybrid mesh was generated and solutions were obtained for various lift fan pressures and air-clearance heights. Computations have been carried out by means of the computational fluid dynamics (CFD) software ANSYS FLUENT. Mean flow aerodynamic characteristics of the ACV are presented and discussed in terms of lift and drag forces, factors contributing to the drag, flow separations and singular points in the streamline patterns. The Q-criterion is employed to identify vortical structures. Differences in the aerodynamic characteristics of an ACV and a road vehicle are also discussed.