Improved performance of an underwater glider with passively rotatable wings

An underwater glider equipped with passively rotatable wings for the use of ocean exploration is presented. The glider is designed to obtain long endurance. We have developed an experimental vehicle as a test facility for an underwater glider with passively rotatable wings. The study is focused on the effect of the wing incidence angle on the gliding distance of the glider. The smaller the gliding angle is, the longer the gliding distance will be. But the gliding angle can´t be obtained directly. For there is a relationship between the gliding angle and the lift/drag ratio, we directly measure the lift/drag ratio so as to obtain the relationship between the gliding angle and the wing incidence angle. In this paper, a computational fluid dynamics (CFD) technique is introduced to calculate hydrodynamic forces acting on the glider. A water tank test is also conducted to validate the simulation results, and it is verified that the experimental underwater glider has hydrodynamic characteristics as expected. Having the capacity to glide with a much smaller gliding angle as compared with conventional fixed-wing underwater gliders, the glider with passively rotatable wings has longer gliding range and endurance.