[medo20051989]

I used ansys design modeler to draw the turbine stage model but there is no option in DM to specify the tip clearance. Is there any other way to elaborate tip clearance in cfx for example after meshing?

Thanks,,

[fresty]

Specifying the tip clearance value could only be done as part of your stage design/ dimensions while modelling in DM/ BladeGen, which probably is only needed if the clearance is significant.. However if it is to only cater the effects of tip clearance then, yes you could find tip clearance activation options in turbo-mode setup in CFX while defining regions of your stage..

[medo20051989]

Thanks alot for your attention. But,Are you sure that tip clearance can be specified in Blade design modeler , I think it's available only in Bladegen.

[fresty]

From what I can recall from top of my head, an easy way of adding hub or shroud tip clearance is using TurboGrid mesh tool..
not sure if Design Modeler has an inbuilt option or has to be manually designed..most probably the latter..

[medo20051989]

Thanks for your attention,,

[medo20051989]

Excuse me, but I've another question cause i used ICEM instead of Turbogrid so after specifying tip clearance at Turbogrid,Is there any exporting interface between icem and Turbogrid or another method to specify tip clearance in icem itslef.

Thanks,,

[fresty]

Not sure if your comprehension of tip clearance is similar to what I think or per CFX terminology.. If you only intend to make the shroud wall stationary then simply activate the tip clearance in CFX turbo setup/ apply wall counter-rotation.. If the idea is to observe dissipation in the periphery of the rotor blade then why not include a simple stationary annular flow body and interface it with blades... You need to supply more details about your objective out of the simulation, precisely regarding tip clearance, to evoke more help (esp. from the more experienced forum members)... About ICEM and TurboGrid, it seems counter intuitive to have an interface between two mesh creation tools when usually TurboGrid works pretty fine when it comes to turbo-machinery simulations...

[medo20051989]

I already used blade design modeler to create the fluid zone including stator and rotor but unfortunately the design modeler create the rotor's shroud as a part of the blade in stator and rotor as well as a single part, after that in Turbogrid you can specify the shroud or tip clearance, but here for a specific objectives of my project i should use ICEM instead of Turbogrid.on the other hand, CFX-Pre provides tip clearance function but it has no effect here since the blade design modeler creates the rotor as a single part of hub,blade and shroud. Eventually, many thanks.

[Bdew8556]

Hey guys,

I'm just wondering about the tip clearance.

How does turbogrid and CFX mesh and solve for those tiny tip clearances?
I assume it doesn't solve it "normally" and instead uses some sort of reduced order model, wall functions perhaps? any comments?

[Gert-Jan]

There is no reduced order model or whatsoever,
You either include it completely or ignore it by extending the tips to join them with the outer surface (shroud).
For both situations in CFX-Pre, let the volume with blade rotate and set the outer surface to counter rotating surface to have it effetively stands still.