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Wave Glider Pressure Vessel

A pressure vessel for an acoustic modem on a Navy Wave Glider, built with NIWC Pacific for my UCSD senior capstone.

Role
Hydrodynamics lead
Sponsor
NIWC Pacific (Naval Information Warfare Center)
Course
MAE 156
Year
2024 to 2025
Tools
SolidWorks, ANSYS (CFD), 3D printing, hydrostatic testing
81.7%
Less drag with the dome
350m
Required operating depth
125%
Of rated pressure, held in hydrostatic testing
FS 3
Factor of safety at 1,000m in FEA

Narrated overview from the team

The project

NIWC Pacific runs Wave Gliders, uncrewed surface vehicles that ride ocean waves on long missions and tow sensor payloads below them on a winch. They wanted to add a ROAM modem (RF, optical, and acoustic) to the Wave Glider so it could talk to other underwater systems. Our five-person team designed the pressure vessel that carries it: mounted inline between the tow cable and the towed acoustic array, rated past 350m, and shaped to add as little drag as possible.

The design

  1. Housing. Anodized 6061-T6 aluminum tube with 7075-T6 end caps, sealed with O-rings and locking flanges.
  2. Internals. Eight 3D-printed strong-backs and bulkheads that slot together and hold the five ROAM electronics: modem PCB stack, relay controller, power distribution, and a LiPo battery. Everything slides out for service.
  3. Hydrodynamic dome. A hemispherical cover printed in ASA carbon fiber, in two halves that lock onto the top end cap around the tow cable.
  4. External mounts. Tow cable and tow array connections, plus clamps and a protective cage for the M27 and M21 transducers.

What I did

  1. Design. Designed the hydrodynamic dome in SolidWorks and 3D printed prototypes to check fit early.
  2. Analyze. Modeled drag with and without the dome at tow speeds of 0.8 to 2.0 knots, and confirmed it in ANSYS CFD. At 2 knots, drag drops from 16.32 N to 2.98 N.
  3. Validate. Hydrostatic testing per ISO 21173 and ASME BPVC V: 50%, 100%, and 125% of the 3.51 MPa rated pressure, ten minutes each, after a vacuum seal test.
  4. Hand off. The vessel passed final checks and the hardware went to NIWC Pacific.

More

I built the team's project site: MAE 156, Team 16