[Apaiva]

Hello Everyone.

First of all this is my first post. I'll try to respect all the forum rules. If I fail, please, I'm sorry!

During my simulations and when I face some problem or doubt, I Always visit this forum.

However there is one problem, in my current simulation, that I couldn't realize what happening...

I'm simulating a bulb turbine - axial turbine, steady state - to evaluate the pressure field on the rotor blades. The componentes I have in my simulation is:

1 - Pre distributor 04 stay vanes;
2 - Distributor 16 guide vanes;
3 - Runner with 4 blades.

During the calculation everything goes well. The calculus converge in a short period of time.

When I take a look at the results I note that the flow from distributor to the runner doesn't come from the all passages. Please, see the pictures.

Another thing is that the pressure field, on the runner blade pressure side, have negative pressures which means that something its wrong and I don't know what it is.

If someone needs more information - a file for example - about this subject to try to help me, please, let me know.

Sorry my English mistakes.

Looking forward to hear from you soon.

Regards

[ghorrocks]

the flow from distributor to the runner doesn't come from the all passages.

You can't use streamlines like this to judge if flow is not going somewhere. The streamlines start from seed points, and if you don't have a seed point there there will be no streamline, even if the flow is going through a passage. Either use more streamlines or a vector field to see what is going on.

the pressure field, on the runner blade pressure side, have negative pressures

This just means the local pressure is negative relative to your reference pressure. If the pressure goes below zero absolute pressure then you might have to think about cavitation, but as long as the minimum absolute pressure remains above the vapour pressure of the liquid this is fine.

[Apaiva]

Hello Glenn!

Thanks for your prompt answer! I appreciate it!

Regarding the streamlines, I'll check it again.

About the pressure field... This equipment exist and will be in operation soon. This calculation is just a double check about the load over the blade during the peak opperational point - I'll use the pressure field to calculate the tensions on the trunion. I suppose that because of the flow through distributor to rotor are not complete in the simulation, I got the low pressure on the blade pressure side instead hi pressure.

Just to let you know: For inlet I specified the net head and, for the outlet at the rotor passage, I specified the total flow mass.

Please, I kindly request from you to take a look at the picture (https://drive.google.com/file/d/0B58...ew?usp=sharing) I send now and make a commemt if necessary.

Once again, tank you very much.

[-Maxim-]

Hi,
your picture link leads to a login window for google. Please attach to your post directly or make it accessible to everyone.