Results 1 to 2 of 2

Thread: Thrust to water flow rate question.

  1. #1 Thrust to water flow rate question. 
    New Member
    Join Date
    Aug 2012
    I am not a scientist, engineer or anything close so please forgive my ignorance. Just looking for some expert advice. If I have an electric tunnel thruster with a 185mm propeller mounted inside a tube of roughly the same diameter as the propeller. and the tube forms a loop with a circumference of about 2 meters. If the tube is filled with water and the thruster is rated to have 211lbs of thrust. Is there a way to determine the flow rate of the water in the tube based on the thrust or do i need more info on the propeller size and rpm and such to determine the waters speed.

    Reply With Quote  


  3. #2  
    Join Date
    Apr 2007
    What you are calling an "electric tunnel thruster" is basically a pump, and your pump is pumping water around a loop of piping. Pumps are supplied by their manufacturer with a pump characteristic curve or "head-flow" curve, and each pump design is different.
    Centrifugal Pump Characteristic Curve - Engineers Edge
    The flow resistance of a pipe can be found in a handbook or a water flow calculator like this one.
    Water Flow Rate Calculator
    What would happen is that an equilibrium flow rate would be reached where the output pressure, or head, of your pump is equal to the resistance of the loop of piping.
    For such a short length of pipe, the flow resistance would not be very great. Your pump may very well be running near "runout" condition as shown on the curve in the first web site link posted above in which case it would not develop anywhere near its rated pressure.

    Edit: Never mind all that. A thruster is a different kind of thing.
    These thrusters have a thrust rating at a certain flow rate.
    If you know the thrust, and the flow rate in gpm, you can find the velocity from the flow rate.

    Last edited by Harold14370; August 10th, 2012 at 04:21 PM.
    Reply With Quote  

Similar Threads

  1. Time flow vs. Entropy flow
    By kojax in forum Personal Theories & Alternative Ideas
    Replies: 1
    Last Post: May 11th, 2011, 01:42 AM
  2. Deduction of thrust force
    By Misr in forum Physics
    Replies: 17
    Last Post: April 12th, 2010, 08:32 AM
  3. calculating diameter of a filter using only flow rate
    By ScienceTKK in forum Mechanical, Structural and Chemical Engineering
    Replies: 1
    Last Post: December 6th, 2008, 12:15 AM
  4. Thrust
    By Raymond K in forum Physics
    Replies: 10
    Last Post: April 11th, 2008, 06:53 PM
  5. rocket thrust idea
    By oracle in forum Physics
    Replies: 3
    Last Post: August 12th, 2006, 11:47 PM
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts