Session: 06-14-02 Underwater Vehicles and Design Technology II

Paper Number: 79677

79677 - Optimization of a Flexible Flapping-Foil Thruster Based on a Coupled BEM-FEM Model 

The biological study of underwater creatures offers inspiration for novel AUV thruster designs achieving energy efficiency, stealth, and advanced maneuverability. Bio-inspired thrusters designed to mimic the propulsive capabilities and mechanisms of fish locomotion pose an alternative to the conventional AUV propeller propulsion [1]. The design, construction, and extensive testing of such bio-mimetic systems, e.g. [2], give the essential proof of concept for future projects. In this work, we examine a particular design concerning the propulsion of an AUV by a flapping-foil thruster, operating at a constant speed that undergoes prescribed heaving and pitching oscillations about its pivot axis [3]. The sectional profile and kinematics of the rigid flapping-foil thruster are selected with a focus on application. Reflecting on the initial biological source of inspiration in aquatic locomotion, researchers suggest that chord-wise flexibility could enhance the overall propulsive performance of flapping-foil thrusters at optimal configurations in terms of material selection, shape, and kinematics [4]. Motivated by this, an optimization study is performed to determine optimal material properties and flexural rigidity distribution for the proposed AUV flapping-foil thruster. An improved propulsion system comes with lower power requirements, thus extending the overall operational capabilities of the system. The objective function for the optimization problem is formulated for the maximization of Froude efficiency with the required thrust, that corresponds to the AUV operational velocity, as a constraint. The targeted design variables include material properties and flexural rigidity distribution, whereas we used the PARSEC methodology for the foil's sectional profile parametrization [5]. The performance assessment of the device is carried out using a fluid-structure interaction (FSI) model based on ideal fluid flow assumptions and Kirchhoff-Love plate theory for cylindrical bending [6]. The proposed coupled boundary element and finite element method (BEM-FEM) has been compared against other methods and experimental data and has been found to be suitable for the prediction of the hydro-elastic response of such systems. The solver predicts the hydrodynamic forces and the elastic response of the system by treating the non-linear FSI problem. Finally, we performed a comparative analysis between the rigid and the passively deforming flapping-foil thruster designs deduced during the hydro-structural optimization process to illustrate that incorporating bio-inspired features leads to significant performance enhancement. This methodology is suitable for the preliminary design of flexible flapping foil thrusters, but it could also facilitate the design process of optimal bio-mimetic systems with flexibility used for wave power extraction and marine renewable energy devices [7].

References

1.         Triantafyllou, M. S., Hover, F. S., Techet, A. H., and Yue, D. K. P. "Review of Hydrodynamic Scaling Laws in Aquatic Locomotion and Fishlike Swimming." ASME. Appl. Mech. Rev. July 2005; 58(4): pp. 226–237.

2.        Licht S., Hover F. and  Triantafyllou M. S. "Design of a flapping foil underwater vehicle", Proceedings of the 2004 International Symposium on Underwater Technology (IEEE Cat. No.04EX869), 2004, pp. 311-316.

3.        Priovolos A., Filippas E. and Belibassakis K.A. "A vortex-based method for improved flexible flapping-foil thruster performance", Engineering Analysis with Boundary Elements, 2018, Vol.95.

4.         Shyy W., Aono H., Chimakurthi S.K., Trizila P., Kang C.-K., Cesnik C.E.S. and Liu H., "Recent progress in flapping wing aerodynamics and aeroelasticity", Progress in Aerospace Science, 2010, Vol. 46(7), pp 284-327.

5.          Vecchia P., Daniele E. and  D’ Amato E. "An airfoil shape optimization technique coupling PARSEC parameterization and evolutionary algorithm", Aerospace Science and Technology, 2014, Vol. 32(1), pp 103-110, Addison-Wesley Professional.

6.       Anevlavi D., Filippas E., Karperaki A. and Belibassakis KA. "A Non-Linear BEM–FEM Coupled Scheme for the Performance of Flexible Flapping-Foil Thrusters", Journal of Marine Science and Engineering, 2020, Vol.8(1), 56.

7.         Jeanmonod G. and Olivier M. "Effects of chord-wise flexibility of 2Dflapping foils used as an energy extraction device", Journal of Fluids and Structures, 2017, Vol.70, pp. 327-345.

Presenting Author: Dimitra Anevlavi National Technical University of Athens

Authors:

Dimitra Anevlavi National Technical University of Athens
Evangelos Filippas National Technical University of Athens
Angeliki Karperaki National Technical University of Athens
Kostas Belibassakis National Technical University of Athens