Research on drag reduction characteristics of underwater vehicle fore region with short groove structures

Based on the typical underwater vehicle configuration, three kinds of drag reduction short groove structures with different cross sectional shapes are designed. The short groove structures are just built on the fore region of the underwater vehicle. Both the numerical simulation technique and experimental test are used to study the drag reduction characteristic of underwater vehicle with short groove structures. It is shown that all these three different cross sectional shapes groove structures can reduce the drag of the underwater vehicle. Compare with Rectangular-shaped and V-shaped groove structures, the U-shaped groove structure can obtain the best drag reduction effect under the same cross sectional area. Also the drag reduction ratio increases with the increased of velocity. The number and size of groove structures can change the drag reduction performance. The numerical simulation results agree well with experimental tests. Through analyzing the fore region flow field characteristic of the underwater vehicle with groove structures, found that the short groove structures changed the flow field structure. The thickness of the underlying viscous sublayer in boundary layer is increased, and the separation of the boundary layer is delayed. Meanwhile, the pressure drag of the fore region which plays the major role in the total resistance of the fore region is reduced. Both these reasons produce the drag reduction of the groove structures.