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Condensing steam

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Old   July 28, 2015, 12:28
Lightbulb Condensing steam
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Hi!

I am working on condensing steam in the last stage of a steam turbine. Is it is possible, or has anyone tried, to first do an Eularian-Eularian multiphase solution, and use this as initial conditions for a Particle Tracking case?

My idea is to first obtain the nucleating steam (droplets of less than 1 micrometer) with fully solved pressure and velocity field, and use this as the initial conditions for a second simulation with particles of water (100 micrometers) that are injected at the inlet with one way coupling (they don't affect the flow). The objective is to see how this "coarse water" travels in the blade path, and how many droplets impact the surface.

I am on my way to trying this, but I am slowly going through the steps, and working on convergence issues with the Eularian-Eularian model...

Thanks in advance on any advice you might have on this type of flow.
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Old   July 28, 2015, 20:10
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I have never done this, it sounds tricky. For instance the eularian bit does not give you specific locations for the particles to seed, just the control volume. So you are going to have to do something to distribute the seeds around the control volume as a function of the water volume fraction.
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Old   July 29, 2015, 05:41
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Hi Ghorrocks! Well, the main reason I want/need to first obtain the eularian-eularian solution is to have a correct pressure and velocity field. When condensation occurs there is a change in pressure due to the latent heat released, but I really don't care about the path of the submicron doplets caused by condensation. I care about the 100 - 500 micron droplets (in real turbines they are produced in the stator blade trailing edge, so they are not part of the condensation process) and how they travel in the rotor blade path.

Can anyone tell me, or show me documentation, regarding how to select/implement/input in CFX the Vukalovich Virial equation of state to define a material (supercooled wet steam)? I want to obtain results with both wet steam formulations ( IAPWS and Vukalovich Virial equation) as I have read they might influence the results due to different accuracy in each.
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Old   July 29, 2015, 07:08
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So lagragian seed points just off the blade trailing edge sounds sensible then.

Your question on EOS sounds like pretty specialised stuff, you would be lucky to find anybody who can help you with that on the forum.

All I can recommend is to read the documentation regarding material properties and to use one of the built in properties if at all possible.
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Old   July 31, 2015, 07:14
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With the Euler-Euler model I take it you're using the particle model? If so consider the most basic case first: equilibrium phase change. This assumes phase change occurs instantaneously.

Then use this as the initial guess for a better non equilibrium phase change simulation where the two phases posses their own energy fields.
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