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-   -   torque calculation (http://www.cfd-online.com/Forums/cfx/21683-torque-calculation.html)

sudhakar October 9, 2005 06:32

torque calculation
 
hello everyone, the calculator in the CFX post is not able to calculate the torque for a specific result file. how to calculate torque using expressions in cfx post. can anyone help me... thank you

Robin October 9, 2005 19:00

Re: torque calculation
 
What exactly are you trying to calculate torque on?

-Robin

sudhakar October 10, 2005 01:51

Re: torque calculation
 
am trying to calculate torque on a blade rotating abt x-axis. by the way what happened to forum at waterloo.ansys site.


Robin October 11, 2005 12:23

Re: torque calculation
 
The CFX Forum was down for a few days due to server problems. It is back up now.

More specific to my question, are you trying to calculate torque on a surface or volume? The torque calculation will not work on a volume.

Regards, Robin

sudhakar October 11, 2005 14:44

Re: torque calculation
 
i need the torque to be calculated for surfaces only. actually some functions(mass flow, massflow ave,torque) are not working for this specific result file. full(all) variables are written to the result file. may be some bug since the file is large. so i need to know how the torque can be calculated (in my case for the surfaces rotating about x-axis- to be particular). regards sudhakar

Robin October 12, 2005 09:58

Re: torque calculation
 
Hi Sudhakar,

It's possible the resutls file is incomplete. You could define an expression to integrate the torque instead by calculating the local Z and Y components of force times the radius.

ty local = Pressure * Area Z * Y tz local = Pressure * Area Y * Z Torque on Blade = int(tz local + ty local)@blade

Regards, Robin

sudhakar October 13, 2005 10:02

Re: torque calculation
 
thanks Robin. But am not able to use that integral function in CEL. It gives some syntax error. so what is the syntax to use integral function -regards sudhakar

Robin October 13, 2005 16:00

Re: torque calculation
 
Sorry, that should have been sum() not int().

-Robin

sudhakar October 14, 2005 07:36

Re: torque calculation
 
Thank you Robin. I checked the expression for a result file(centrifugal pump) where i was able to calculate the torque using the calculator. but the value (for one blade surface) that i get using the expression is double than that i get from the functional calculator. is there anything wrong in the torque expression procedure i follow...my case is a centrifugal pump rotating abt x axis tylocal = Pressure * AreaZ * Y AreaZ = Area * Normal Y Similarly tzlocal = Pressure * AreaY * Z AreaY = Area * Normal Z

Torque on blade = sum(tylocal+tzlocal)@bladesurface


Robin October 14, 2005 08:33

Re: torque calculation
 
Area Z = Area * Normal Z Area Y = Area * Normal Y


sudhakar October 15, 2005 10:17

Re: torque calculation
 
then too the value is about twice of the value got from the functional calculator.

Robin October 17, 2005 09:35

Re: torque calculation
 
Hi Sudhankar,

I just checked on one of my results files and the answers nearly match (there will be a slight difference, since the torque calculation uses the integration point values). My expressions are:

EXPRESSIONS:
Area Z = Area * Normal Z
Area Y = Area * Normal Y
ty local = Pressure * Area Z * Y
tz local = Pressure * Area Y * Z
Torque on Blade =sum(tz local + ty local)@BLADE
END
If you still see a difference, make sure your expressions are correct for your axis of rotation and that your regions are the same.

Regards,
Robin

ravinandan November 11, 2005 07:04

Re: torque calculation
 
dear sir

please the details regarding the torque calculations for Dc motor

and all other related issues

thanking you ravinandan

prashant ranjan maurya December 9, 2005 02:34

torque calculation
 
dear sir

please send the details regarding the torque calculations for Dc motor

and all other related issues

thanking you.


C S KALLIGUDDA December 19, 2005 06:38

Re: torque calculation
 
How to calculate the torque for all applications. methods

T.SELVAMUTHUKUMAR January 5, 2006 10:08

Re: torque calculation
 
we are the manufacturer of orbital shaker.we had problem to select a ac motor for our application.our requirement listed below. speed reduction ratio:1:4.how to select a motor whether based on torque or rpm requirement?


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