relative velocity for a radial turbine wheel

nikwin · December 15, 2011, 04:45

Hi all,

I have a set of transient data for a radial turbine including the event file (.evn) and would like to compute the relative velocities in the wheel. The wheel rotation is simulated with the sliding mesh technique. Could anyone please give me a hint of how to or point me to a relevant tutorial.

Thanks
/NW

JBeilke · December 15, 2011, 07:20

Use the "reframe" command.

nikwin · December 15, 2011, 07:24

Thanks for your quick reply!

I've tried the following, reframe,2,local,(OMEGA), used the second coordinate system with the following command, csys,2 and then tried to extract the data again. However, it subtracts the data from the entire field and not just from the wheel. Do you know how I can specify a part of the field to get relative velocities at the wheel only?

All the Best
/NW

JBeilke · December 15, 2011, 08:48

There are 3 possibilities for using the command.

refr stat
refr compu
refr loca icsys omega

Just try what gives the best results.

I don't see an easy solution for the other problem right now.

RobertB · December 15, 2011, 11:54

I would think that you should be able to get there from here with OPERATE and CHANGE

If you use PSYS to set the basic system for post processing

Then you can

Getc,all

to get the vectors in the axis of the rotor

Oper getc x axis_syst 5

Oper smult omega 5 5

Cset news all non rotating cells

change cset 0 0 0.0 0.0 5

oper subt 2 5 2

Oper unrotate

Not sure if this does exactly what you want but some combination of the above commands or similar should get you there from here

nikwin · December 22, 2011, 10:33

Thank you! The command oper,refr,local,(coord syst),(omega) did the trick!

All the Best
/NW

December 15, 2011, 04:45	relative velocity for a radial turbine wheel	#1
nikwin Member Niklas Winkler Join Date: Mar 2009 Location: Stockholm, Stockholm, Sweden Posts: 72 Rep Power: 5	Hi all, I have a set of transient data for a radial turbine including the event file (.evn) and would like to compute the relative velocities in the wheel. The wheel rotation is simulated with the sliding mesh technique. Could anyone please give me a hint of how to or point me to a relevant tutorial. Thanks /NW

December 15, 2011, 08:48		#4
JBeilke Senior Member Joern Beilke Join Date: Mar 2009 Location: Dresden Posts: 112 Rep Power: 5	There are 3 possibilities for using the command. refr stat refr compu refr loca icsys omega Just try what gives the best results. I don't see an easy solution for the other problem right now.

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December 15, 2011, 07:20		#2
JBeilke Senior Member Joern Beilke Join Date: Mar 2009 Location: Dresden Posts: 112 Rep Power: 5	Use the "reframe" command.

December 15, 2011, 07:24		#3
nikwin Member Niklas Winkler Join Date: Mar 2009 Location: Stockholm, Stockholm, Sweden Posts: 72 Rep Power: 5	Thanks for your quick reply! I've tried the following, reframe,2,local,(OMEGA), used the second coordinate system with the following command, csys,2 and then tried to extract the data again. However, it subtracts the data from the entire field and not just from the wheel. Do you know how I can specify a part of the field to get relative velocities at the wheel only? All the Best /NW

December 15, 2011, 11:54		#5
RobertB Member Robert Join Date: Jun 2010 Posts: 83 Rep Power: 4	I would think that you should be able to get there from here with OPERATE and CHANGE If you use PSYS to set the basic system for post processing Then you can Getc,all to get the vectors in the axis of the rotor Oper getc x axis_syst 5 Oper smult omega 5 5 Cset news all non rotating cells change cset 0 0 0.0 0.0 5 oper subt 2 5 2 Oper unrotate Not sure if this does exactly what you want but some combination of the above commands or similar should get you there from here

December 22, 2011, 10:33		#6
nikwin Member Niklas Winkler Join Date: Mar 2009 Location: Stockholm, Stockholm, Sweden Posts: 72 Rep Power: 5	Thank you! The command oper,refr,local,(coord syst),(omega) did the trick! All the Best /NW