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-   -   A little instruction please ! (http://www.cfd-online.com/Forums/cfx/120475-little-instruction-please.html)

helloabc1234 July 8, 2013 06:49

A little instruction please !
 
First may i point out that info from this forum has helped me a lot in my Final Year Projet (BE Mechanical).
Now i have my project defence presentation tomorrow so i need some quick help here.
I have simulated a turgo turbine in cfx. So i want the solver to calculate the outputs(only one actually, torque about the z-axis) for multiple input RPMs(entered in tubo mode of CFX-Pre). I do not need it for a varying RPM, just a few values. And after that i would keep the RPM constant and enter multiple values for the inlet flow rate.
I am looking to plot efficiency against RPM and then against flow rate. Torque could be tied up with efficiency by a simple formula, by a constant factor in fact. So if i could get a graph in CFX Solver or CFX-post, that would be just great.
Like i said i could find out the way but it might take a lot of time (if there even is one), So i've come to you guys.....

Editing just to point out that there is no macro for performance evaluation of impulse turbines in CFX.

ghorrocks July 8, 2013 08:15

Have a read of the best practises buide for turbo machinery, it has lots of good tips.

I am not completely sure what you are trying to do. If you have run a range of RPM and flow rates - then can't you get the steady state operating point at each RPM then you can plot the operating point curve?

helloabc1234 July 8, 2013 12:45

That's the point - HOW do i get the steady state operating point at each RPM and flow rate ? I do have the RPMs and flow rates........
Do i have to run the solver again for every change in RPM or flow rate value?

I was going to reply earlier with the message above, but there is a power shortage problem where i live. Now i have gotten the torques at the different RPMs by obtaining a solution for every value.

techCAE July 9, 2013 04:49

1 Attachment(s)
There is a Turbo macro available in the CFX Post, you can use it for full performance results and if you are using CFX via ANSYS Workbench, you can plot the outputs as a graph automatically.
You can create a design table in Workbench by using different values of Speed and Flow.

helloabc1234 July 10, 2013 12:44

1 Attachment(s)
There is a turbo macro but it is not for 'impulse turbines'. For instance there is no concept of a shroud in an impulse turbine. Major other differences as well. I think you can simulate the turbine in CFX-Pre but not by using turbo mode. I did manage to devise it using the turbo mode somehow but the results show that it didn't work.


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