Abstract
A manta ray biomimetic glider is designed and studied with both laboratory experiments and numerical simulations with a new dynamic update method called the motion-based zonal mesh update method (MBZMU method) to reveal its hydrodynamic performance. Regarding the experimental study, an ejection gliding experiment is conducted for qualitative verification, and a hydrostatic free-fall experiment is conducted to quantitatively verify the reliability of the corresponding numerical simulation. Regarding the numerical simulation, to reduce the trend of nose-up movement and to obtain a long lasting and stable gliding motion, a series of cases with the center of mass offset forward by different distances and different initial angles of attack have been calculated. The results show that the glider will show the optimal gliding performance when the center of mass is 20mm in front of the center of geometry and the initial attack angle range lies between A0 = -5° to A0 = -2.5° at the same time. The optimal gliding distance can reach six times its body length under these circumstances. Furthermore, the stability of the glider is explained from the perspective of Blended-Wing-Body (BWB) configuration.
Highlights
Manta rays, known as "devil fish," have evolved for approximately 100 million years, but they still retain the appearance of their ancestors: a flat body in the shape of a diamond
A comparison of the trajectory and attitude of the glider whose center of mass (CoM) is situated at center of geometry (CoG) under different initial gliding velocities is shown in Fig 8, where X, Z, L and θ represent the displacement component in the X direction, the displacement component in the Z direction, the body length of the model, and the angle relative to the initial state, respectively
In order to simulate the unconstrained six-DOF motion of manta ray biomimetic glider, the motion-based zonal mesh update method (MBZMU method), one original dynamic mesh update method proposed by the authors is further improved by replacing a sphere of the core zone into a cylinder
Summary
Known as "devil fish," have evolved for approximately 100 million years, but they still retain the appearance of their ancestors: a flat body in the shape of a diamond. A study on the hydrodynamic performance of manta ray biomimetic glider under unconstrained six-DOF motion aquatic flapping and found that the most important propulsion was produced from the distal end of the fins, the highest propulsive efficiency was found for Strouhal numbers St = 0.2~0.4. Fish et al [5] measured the turning performance of manta ray from the movies and found that they often make small radius turns due to the rigid body with the highest speed of 67.32 deg/s These studies are much useful for the design and further research of bio-inspired autonomous underwater vehicles (BAUVs). Wang et al [18] studied the hydrodynamic performance of the biomimetic manta ray underwater glider numerically They found that manta ray has better hydraulic performances with a large angle of attack and a small attitude angle while gliding. In order to evaluate the gliding ability and hydrodynamic performance of the glider, both experiments and numerical simulations are carried out under different gliding conditions
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