A CFD based investigation of the unsteady hydrodynamic coefficients of 3-D fins in viscous flow

Abstract

The motion of the fins and control surfaces of underwater vehicles in a fluid is an interesting and challenging research subject. Typically the effect of fin oscillations on the fluid flow around such a body is highly unsteady, generating vortices and requiring detailed analysis of fluid-structure interactions. An understanding of the complexities of such flows is of interest to engineers developing vehicles capable of high dynamic performance in their propulsion and maneuvering. In the present study, a CFD based RANS simulation of a 3-D fin body moving in a viscous fluid was developed. It investigated hydrodynamic performance by evaluating the hydrodynamic coefficients (lift, drag and moment) at two different oscillating frequencies. A parametric analysis of the factors that affect the hydrodynamic performance of the fin body was done, along with a comparison of results from experiments. The results of the simulation were found in close agreement with experimental results and this validated the simulation as an effective tool for evaluation of the unsteady hydrodynamic coefficients of 3-D fins. This work can be further be used for analysis of the stability and maneuverability of fin actuated underwater vehicles.

Keywords

oscillating 3-D fin / RANS / hydrodynamic performance / viscous flow

References

[1] Barrett D., Grosenbaugh M., Triantafyllou M. The optimal control of a flexible hull robotic undersea vehicle propelled by an oscillating foil. Symp. Aut Underwater Veh. Tech., 1996, 3(2): 1-9

[2] Childress S. Mechanics of swimming and flying, 1981, Cambridge: Cambridge University Press, 226-236

[3] Domenici P., Blake R. The kinematics and performance of fish fast-start swimming. J. Exp. Biology, 1997, 200: 1165-1178

[4] Kelly S, Mason R, Anhalt C, Murray R, Burdick J (1998). Modeling and experimental investigation of carangiform locomotion for control. Proceedings of the 1998 American Control Conference, Boston, 837–841.

[5] Liu J, Dukes I, Knight R, Hu H (2004). Development of fish-like swimming behaviors for an autonomous robotic fish. Proceedings of the Control. University of Bath, IEEE, Bristol, 1165–1170.

[6] Mason R, Burdick J (1999). Propulsion and control of deformable bodies in an ideal fluid. Proc. IEEE Int. Conf. Rob. Aut, Tokyo, 1035–1040.

[7] Newman J., Wu T. Hydrodynamical aspects of fish swimming, in swimming and flying in nature., 1975, New York: Plenum Press, 15-34

[8] Saimek S, Li P (2001). Motion planning and control of a swimming Machine. Proceedings of the 2001 American Control Conference, New York, 1915–1919.

[9] Spierts I., van Leeuwen J. Kinematics and muscle dynamics of C- and S-starts of carp. J. Exp. Biology, 1999, 202: 393-406

[10] Streitlien K., Triantafyllou G.S. Efficient foil propulsion through vortex control. AIAA Journal, 1996, 34(11): 2315-2318

[11] Vela P, Morgansen K, Burdick J (2002). Second order averaging methods for oscillatory control of under actuated mechanical systems. Proceedings of the 2002 American Control Conference, Houston, 2315–2321.

[12] Wang F.J. The Analysis of computational fluid dynamics-the theory and application of CFD software, 2004, Beijing: Tsinghua University Press, 120-126

[13] Weihs D. A hydrodynamical analysis of fish turning maneuvers. Proc. R. Soc. Lond. B, 1972, 182: 59-72