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I Jet Spread Rate K Values- Momentum diffusement

  1. Oct 23, 2016 #1
    upload_2016-10-24_11-11-30.png
    The Problem Statement
    I have a jet entering leaving a nozzle at ui into an ambient fluid with ue = 0
    I am trying to equate the rate of momentum diffusement (or spread) to the shear forces caused by ue -ui


    I understand that the rate momentum diffusement is are equated by empirical K- values (~0.1 for turbulent flow ~0.4 for laminar flow)

    The Question

    Is there any way to calculate the rate of momentum diffusement or spread directly from ui -ue
    I am trying to understand what would happen as the flow develops from ui=0, ue = 0
    Would the momentum diffusement always equal the rate of flow development or does K values < 1 indicate that a the momentum diffusement is inadequate to prevent a velocity gradient.

    Attempt at a solution
    I am thinking that it does as there is a length to the initial region where this occurs.
    A K-value of 1 would indicate an immediate dispersal of any additional increase in ui
    so no shear forces could ever develop.[/sub] and therefore no motive to cause a diffusement . A cyclical argument.
    I think the K value must factor the viscosity of the fluid and its Reynolds number

    Edit : sorry one other question, the initial region length is described as 5 diameters in length . Is that representative of a k value of 0.2
    $$\frac{1D}{0.2}=5D$$
     

    Attached Files:

    Last edited: Oct 23, 2016
  2. jcsd
  3. Oct 29, 2016 #2
    Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.
     
  4. Jan 13, 2017 #3
    I'm sorry I don't have an answer for you but I was wondering if you could help me. Do you know of an underwater pressure nozzle that can increase the pressure and volume of the fluid mass by pulling in fluid from the surrounding areas of fluid around the exterior of the nozzle possibly with a Venturi or jet pump type opening before the nozzle's release?
     
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