Calculating the thrust required to turn a submarine deep in the water

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Discussion Overview

The discussion revolves around calculating the thrust required for a submarine, specifically an Autonomous Underwater Vehicle (AUV), to turn at a steady angular velocity while submerged. Participants explore various factors influencing this calculation, including drag, propulsion power, and external currents.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant seeks assistance in determining the power needed for a bow thruster to achieve a steady angular velocity for their AUV.
  • Another participant suggests that the power requirement could vary significantly, estimating it to be around 0.1 HP, and emphasizes the need for details about the AUV's specifications.
  • A request is made for formulas or procedures to calculate drag while turning for any typical AUV.
  • One participant posits that drag may be minor compared to forces from currents at angles like 45 degrees and proposes a method to estimate power requirements based on current resistance.
  • A later reply indicates a preference for mathematical approaches over experimental methods.
  • Another participant suggests the possibility of using 360-degree rotating propulsion pods instead of a separate thruster, referencing modern ship designs.

Areas of Agreement / Disagreement

Participants express varying opinions on the factors influencing thrust requirements, with no consensus on specific calculations or methods. The discussion remains unresolved regarding the exact power needed and the best approach to calculate it.

Contextual Notes

Participants have not provided specific assumptions or constraints regarding the AUV's design, operational environment, or the nature of the currents, which may affect the calculations discussed.

Riyadh
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Dear All,

I am designing a AUV and trying putting a bow thruster in the front. I am kinda confused that how much power do I need to turn my AUV by a steady angular velocity. Could anyone pls help me with this.

Regards
 
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Working blind here.
Power could be any value. I am guessing it should be about 0.1 HP.

Firstly, briefly describe your AUV - weight, size, power consumption, duration of underwater expedition, desired time to make a turn, etc. That might cog someone with experience with a similar problem or knowledge of underwater vehicles to offer aid.

You must at least have some idea of what your desired goal is.
And how much knowledge you have on this subject would not hurt either.
 
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I am looking for the formulas or the procedure to calculate the drag while turning for any typical AUV of any size.
 
I would guess that drag is small compared to the forces caused by currents impinging at angles such as 45 degrees.

Here is a way to guess. Calculate, or fiind by experiment, how much primary propulsion power is needed to hold the vessel stationary against X knots of current bow-on. The power needed by the thruster and rudder to hold constant angle against X knots at 45 degrees is comparable within a factor of two.

Your biggest job is to decide how much X to design for. Unless you are in a swimming pool, X is seldom zero.

Good luck
 
Ah, Cant do experiments. Anything mathematically
 
Can you make the primary propulsion in pods that rotate 360 degrees? Modern ships do that. One pod fore, one aft and you have it. No separate thruster needed.
 

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