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How to use a fuel regulator and where to place it?

  1. Oct 29, 2012 #1
    I have to design and construct an fuel system in one of my projects.

    In this project, im designing fuel system which uses liquid fuel.

    The fuel is meant to be burnt in a gas turbine engine - thus the fuel will be injected in atomized form inside the combustion chamber.
    ___________

    There is possibility of pressure drop inside the combustion chamber.

    Constant fuel flow has to be maintained to the combustion chamber, and the fuel flow will be controlled with a single valve/tap.


    Problem/Question
    Since pressures can drop in the chamber, the fuel flow can increase on its own.

    [itex]\overbrace{}^{}m[/itex]=Cd * A [itex]\sqrt{}z [itex]\rho[/itex] [itex]\Delta[/itex]p[/itex]

    Thus to maintain constant fuel flow, a pressure regulator has to be used which maintains constant pressure to maintain constant fuel flow rate. (incase there is a drop in pressure in the combustion chamber or increase in fuel tank or vice versa)

    I do not understand how to use a pressure regulator? and where to place it...

    and other information associated with the pressure regulator will be very helpful.
     
  2. jcsd
  3. Oct 29, 2012 #2

    Averagesupernova

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    Gold Member

    I would assume that you are aiming for constant pressure at the nozzle(s). Do a little searching on pressure regulators in general. Wiki is always a place to start.
     
  4. Oct 29, 2012 #3
    Yes,

    I am aiming for a constant pressure at the nozzle. The regulator must be able to deal with pressure drop in the combustion chamber or pressure drop in the tank by being able to maintain constant pressure.


    And i want to change the fuel flow rate by changing the area of the valve/orifice - that is opening the "handle".

    i tried reading on wiki, but they explain the mechanisms.

    for this project, its allowed to buy the individual components and assemble them to form the fuel system.

    it would be great, if someone can give some info for me about placing these regulator and valve.

    i placed a schematic, if someone can roughly give me an idea of where to place what...



    EDIT:-------

    I did reading on pressure regulators...
    i will try to explain what i understood, correct me please if i am wrong.

    According to the selected design, the method of controlling the fuel flow rate is : Fix pressure difference between the metering valves and vary the valve/orifice size to alter the fuel flow rate.
    _________

    Here's what i understood

    Selected Fuel regulator/valve location = Between the fuel pump and the nozzle.

    Selected regulator - Single Stage Pressure Regulator ('as shown on wiki')

    Possible factors that can arise-
    1) Increase or decrease in pressure in the combustion chamber (after the injector/nozzle)
    2) Pump pressure going excessively high.

    Will it cope in the following conditions-

    Will it deliver a constant fuel flow no matter conditions 1 or 2 arise (change in backpressure/front pressure)???

    Now if i want to change the fuel flow rate, i move the valve/handle to fix another constant fuel flow rate.

    How correct is the above information
     

    Attached Files:

    Last edited: Oct 29, 2012
  5. Feb 18, 2013 #4
    Most automotive systems use a pressurized rail with a regulator that allows pressure to build and bleed off as it exceeds or drops below the rating. The supply pump typically supplies a bit more than ever would be needed to accommodate for longer injector cycle times. You might use some sort of accumulator as in place of a rail to help deal with increases in fuel flow


    Pressure regulators typically use a calibrated spring or a diaphragm...some also use a spring/diaphragm and engine vacuum to regulate pressure. So as the vacuum increases or decreases the flow reacts accordingly.
     
    Last edited: Feb 18, 2013
  6. Feb 18, 2013 #5

    etudiant

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    Gold Member

    Turbines usually use fuel pumps that provide much more flow than the engines actually require. This ensures a pretty steady pressure at the injectors and also helps keeps the injectors from coking up. The unused fuel gets recirculated.
    This setup allows your engine control to be modulated fairly independently, perhaps with a variable fuel flow orifice as you have indicated.
     
  7. Feb 18, 2013 #6
    done with the design phase of the project =)
    now its time to purchase components to construct the fuel system for the combustor.
     
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