The wind-dispersed seeds can rotate and fall like small
vehicles
with the help of the wind to obtain a longer propagation distance.
Inspired by this, we propose a novel bubble-driven three-bladed whirling-swimmer
(WS) to travel in the fluid as a vehicle. Four types of WSs with blade
folding angles (φ) ranging from 10 to 60° were designed,
and their swimming performance was evaluated. Regardless of the WS
shape, the velocity increases linearly with φ, while the angular
frequency exhibits an asymptotic value. Further, both the St and rotational energy of the WS peak at 20° ≤
φ ≤ 30° for different WS shapes as well as the vertical
force and the hydrodynamic torque were solved from a proposed mechanics
model. This folding angle range is unexpectedly consistent with the
coning angle during maple samaras’ stable falling. The WS lift
and drag forces greatly depend on the interaction between the leading-edge
vortex and the hub vortex. The results showed that the WS-IV seems
to have the highest performance. Our work may shed new light on developing
unpowered wireless swimmers of high swimming performance to provide
a new way for underwater information collection, information transmission,
and enhanced mixing.