Abstract
Torpedo shaped autonomous underwater vehicles (AUVs) displays poor
hydrodynamic efficiency at low crusing speeds, resulting in endurance and
mission effectiveness. This study investigated the integration of cephalofoilinspired
structures, which were modelled after hammerhead sharks (Smooth,
Scalloped, and Winghead), onto the bow of torpedo-shaped AUVs. The design
could improve low-speed manoeuvrability while maintaining hydrodynamic
efficiency. Computational fluid dynamics (CFD) simulations were also
conducted to replicate surge, pitch, and yaw manoeuvres at velocities ranging
from 0.4 m/s to 1.2 m/s and yaw angles from 5° to 25°. The Smooth design
utilising the NACA 3412 profile (450 mm span length) then achieved a peak liftto-
drag ratio (CL/CD) of 10.03. In contrast, the Control design (torpedo hull
without cephalofoil) attained a CL/CD ratio of 1.98. This finding demonstrated a
fivefold enhancement in hydrodynamic efficiency for the Smooth design during
surge manoeuvres. The Smooth design also attained CL/CD values between 6.39
and 10.68 during yaw manoeuvring conditions while producing the smallest
turning radius of approximately 0.67 body lengths (BL). This outcome
represented a nearly 50% reduction compared to conventional torpedo hulls
(~1.2 BL). Energy consumption analyses during the yaw manoeuvres further
revealed that the Smooth design decreased power demands by 80% and 65% at
0.8 m/s against the Control and other cephalofoil designs, respectively. The
pressure and velocity contour analyses then verified that delayed flow separation
and stable vortex generation were the primary mechanisms facilitating these
improvements. Overall, these cephalofoil-inspired bow integration effectively
served as a low-complexity and passive manoeuvring strategy, enhancing agility
and endurance for extended-duration ocean exploration and reconnaissance
missions.
hydrodynamic efficiency at low crusing speeds, resulting in endurance and
mission effectiveness. This study investigated the integration of cephalofoilinspired
structures, which were modelled after hammerhead sharks (Smooth,
Scalloped, and Winghead), onto the bow of torpedo-shaped AUVs. The design
could improve low-speed manoeuvrability while maintaining hydrodynamic
efficiency. Computational fluid dynamics (CFD) simulations were also
conducted to replicate surge, pitch, and yaw manoeuvres at velocities ranging
from 0.4 m/s to 1.2 m/s and yaw angles from 5° to 25°. The Smooth design
utilising the NACA 3412 profile (450 mm span length) then achieved a peak liftto-
drag ratio (CL/CD) of 10.03. In contrast, the Control design (torpedo hull
without cephalofoil) attained a CL/CD ratio of 1.98. This finding demonstrated a
fivefold enhancement in hydrodynamic efficiency for the Smooth design during
surge manoeuvres. The Smooth design also attained CL/CD values between 6.39
and 10.68 during yaw manoeuvring conditions while producing the smallest
turning radius of approximately 0.67 body lengths (BL). This outcome
represented a nearly 50% reduction compared to conventional torpedo hulls
(~1.2 BL). Energy consumption analyses during the yaw manoeuvres further
revealed that the Smooth design decreased power demands by 80% and 65% at
0.8 m/s against the Control and other cephalofoil designs, respectively. The
pressure and velocity contour analyses then verified that delayed flow separation
and stable vortex generation were the primary mechanisms facilitating these
improvements. Overall, these cephalofoil-inspired bow integration effectively
served as a low-complexity and passive manoeuvring strategy, enhancing agility
and endurance for extended-duration ocean exploration and reconnaissance
missions.
| Original language | English |
|---|---|
| Journal | Journal of Applied Fluid Mechanics |
| Publication status | Accepted/In press - 2025 |