Turbogrid and Negative volume
 

hello everyone, I know that this is a repeated question. But I can not solve the problem of negative volume at Turbogrid. I have always negative volume and moving the points donot help (takes a lot of time and finally negative volumes). I also want to change the number of blocks at the shroud without hanging the nubmer at hub. Thank you for help. Happy holiday.. Ali

Re: Turbogrid and Negative volume
 

I found for myself that I can get better mesh form ICEM as fast as from TurboGrid...maybe even faster - less blocks - less headache...

Re: Turbogrid and Negative volume
 

Thanks Luther, Does ICEM work with turbomachines? Ali

Re: Turbogrid and Negative volume
 

Go to the Template pull down menu and then try flipping your topology and profile. You'll need to rearrange you points afterwards - however just do it roughly. Then check your grid for negative volumes. If you no longer have negative volumes go back in and tidy up your points.

That's how I generally solve the problem.

Roy

Re: Turbogrid and Negative volume
 

Thank you Roy, I just used Turbogrid from 1 week ago. I want to know what do you mean by "Template pull down menu" and would you explain how to perform this flipping..About arranging the point it takes a lot of time and does not work in my geometry. Ali

Re: Turbogrid and Negative volume
 

In the bar along the top of the Turbogrid, there is a button called Template. If you click on it it will produce a menu - which includes the two flipping options I mentioned.

Cheers

Roy

Re: Turbogrid and Negative volume
 

Thanks Roy for quick response. I'm using Turbogrid 2.2 and there is no Tempelate button. What is the version that you use? Thanks again Ali

Re: Turbogrid and Negative volume
 

hello everyone again.. I'm using Turbogrid 2.2 and I get negative volumes. I moved control points and get no negative volume, but CFX solver says "there exists negative volume!!!" Anyone can help... Ali

Re: Turbogrid and Negative volume
 

If you use TG 2.2, I highly recommend you to get TG 2.2.1. There is big improvement from 2.2 to 2.2.1. Which topology do you use? One thing I think may help is to inspect mesh from hub to shroud. By default, TG only shows grid on hub, shroud, and one span location. Sometimes, mesh on those surfaces may look perfect but problem still exists at other locations.

Re: Turbogrid and Negative volume
 

Hello Gang, I use H-Grid and O-Grid for topology. I think the problem in my gemoetry that the blade have sharp cut. Around the tail and lead end the mesh intersect causing negative volume. I have TG 2.2 only. What you suggest? I also I can see a good mesh in BLADEgen how can I transfer it to CFX? Thanks.. Ali

Re: Turbogrid and Negative volume
 

TG 2.2.1 has a new feature to handle sharp cut LE or TE. You should give it a try. It's very possible that your problem will be solved by TG 2.2.1.

Maybe BladeGen file can be imported into CFX-Pre directly. If not, you can convert BladeGen file into CGNS format in CFX launcher. CFX-Pre can read CGNS file.

Thank you Gang
 

Thank you Gang for Reply and Happy NEw Year.. Ali

Hello , can anyone helps me to adjust the control points? the idea behind it?
Thanks