How to keep the flow parralell (inlet of blade row)

Gaëtan47 · December 5, 2017, 12:08

Dear all,

I'm trying to simulate a row of steam turbine blade in a 100m/s flow of steam.

My problem is that I have more flow at the top of my simulation than at the bottom (see screenshot). Do you have an idea on how to keep the stream lines parralell and then having the same amount of flow going between the blades?

Simulation used is SST reynolds.

ghorrocks · December 5, 2017, 17:27

Your problem is just that the seed points of the streamlines are not evenly spread. The default option for the seed points puts them in every nth node, but that bunches them up when the mesh density changes. You need to define a seed which is evenly spread. Have a look at the streamline options for the seeds, or you could define your own plane or line and use that.

Gaëtan47 · December 5, 2017, 19:34

If I understand well you suggest that the only the streamline plot is not correct? The thing is that from the color it is possible to see that the velocity is much higher at the top of the top blade than the others. Also the angle of attack is different for every blades. I would like to have the same angle of attack for each blades.

ghorrocks · December 5, 2017, 22:47

Streamlines are integrated from a point. You have to define where that starting point is - that is what the seed points are.

Streamlines are just post processing - if they do not appear to be showing a correct result then the simulation is likely to be inaccurate. This leads onto questions about simulation accuracy, and that is discussed in your other thread (Turbine blade in steam tunnel: configuration and y+ issues)

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December 5, 2017, 17:27		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,716 Rep Power: 143	Your problem is just that the seed points of the streamlines are not evenly spread. The default option for the seed points puts them in every nth node, but that bunches them up when the mesh density changes. You need to define a seed which is evenly spread. Have a look at the streamline options for the seeds, or you could define your own plane or line and use that.

December 5, 2017, 19:34		#3
Gaëtan47 New Member Gaeëtan Join Date: Dec 2017 Location: Paris Posts: 17 Rep Power: 8	If I understand well you suggest that the only the streamline plot is not correct? The thing is that from the color it is possible to see that the velocity is much higher at the top of the top blade than the others. Also the angle of attack is different for every blades. I would like to have the same angle of attack for each blades.

December 5, 2017, 22:47		#4
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,716 Rep Power: 143	Streamlines are integrated from a point. You have to define where that starting point is - that is what the seed points are. Streamlines are just post processing - if they do not appear to be showing a correct result then the simulation is likely to be inaccurate. This leads onto questions about simulation accuracy, and that is discussed in your other thread (Turbine blade in steam tunnel: configuration and y+ issues)