When submarines are using Air-Independent-Power, they are typically traveling less than 10 knots. The submarines can travel faster if it is using batteries or a diesel engine. Propulsive efficiency at low speeds is important for submarines that are not nuclear powered, but all submarines must overcome the hydrodynamic drag from the hull moving through the water. The power required from the battery/powerplant scales with the cube of the velocity.
Reynolds numbers for submarines in seawater is around 1000-2000 when moving at 1 or 2 kts. Submarine propulsion system design focuses on design speed, (close to top speed), as efficiency isn’t a problem at extremely low speeds. Due to the massive power required to operate at high speeds, most submarines don’t move as fast as surface ships, with the variance of speeds may be a factor of 4. Submarines also operate with the same load over a wide range of speeds.
Submarines typically have a higher submerged speed because there is no wave friction. Nuclear submarines can travel around 30-35 kts (60 kph)
[[Submarine Range]] – low speed necessary for range
[[Submarine Endurance]] – low speed necessary for endurance
[[Bulk Carrier Speeds]]
Nuclear-Powered Submarines – can have higher submerged speeds as nuclear gives them unlimited power
[[SMX Ocean]] – 1 month of underwater slow-speed operation
[[Cargo Submarines]]
Submarine Drag Model]] – include the submarine speed in a simple drag model
Sources
- [1] H I Sutton, Apex Predators: AIP Submarines Explained by Covert Shores (Air Independent Propulsion), (Jul. 30, 2021). Accessed: Nov. 28, 2022. [Online Video]. Available: https://www.youtube.com/watch?v=c2QS_aEsVuw
- [2] A. Morrison, “A comparison of pumpjets and propellers for non-nuclear submarine propulsion”.
- [3] LiIonSubTech
- [4] M. Ragheb, “Nuclear Naval Propulsion,” in Nuclear Power – Deployment, Operation and Sustainability, P. Tsvetkov, Ed., InTech, 2011. doi: 10.5772/19007.
- [5] “Status-6 / Kanyon – Ocean Multipurpose System – Russian and Soviet Nuclear Forces.” Accessed: Feb. 27, 2024. [Online]. Available: https://www.globalsecurity.org/wmd/world/russia/status-6.htm
Backlinks
[[Aerodynamic Drag]]
[[Air Independent Power]]
Nuclear-Powered Submarines
[[Propeller]]
[[Reynold’s Numbers]]
[[Stealth Submarines]]
Submarine Drag Model