# Setting condition on a VAWT

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 May 4, 2013, 03:30 #121 New Member   bhushan patil Join Date: May 2012 Posts: 19 Rep Power: 7 to cfd les which mehtode u r using for find out moment and plz share u r images of mesh file ...as i share it .....will specify all details then i will able to help u ...........

 May 4, 2013, 03:41 #122 Super Moderator   Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,358 Blog Entries: 6 Rep Power: 45 Dear Patil, What is relation of moment to torque? I mean how do you convert moment to torque?

 May 4, 2013, 03:45 #123 New Member   bhushan patil Join Date: May 2012 Posts: 19 Rep Power: 7 i am taking moments from report forces --moments -- here u have to specify centre of roatations of moments which u wanted if u r centre is zero zero then give centre of roations =00 ... ya i am taking that momont is torque ....

May 27, 2013, 15:07
#124
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Quote:
 Originally Posted by esp-m1000 Hi nana, sorry, when i wrote "HAWT like yours" i mean VAWT. But the Cp values i gave to u are right. I'm doing simulation on a VAWT similar to yours but i have 5 blades instead of 4 and a non-symmetric airfoil. But this don't mean ur turbine works with drag; Lift is always bigger than drag for airfoil, if they work in normal condition (no-stall). So your turbine works with lift. I have looked at your model, i think that cylinder surface are too near blades, and the free stream volume is also too little. I think u must have a bigger cylinder in whinch locate the turbine and a bigger free stream volume. If u can't becouse u have to simulate in a real wind tunnel maybe u have to use a scaled model and so reduce the scale of your model. For my simulations I have a problem, i had a report moment of 7600 N-m, how i can obtain the power? as i wrote after if i multiply for the time step i obtain a too high value.....

hi dear esp
i have the problem as you had.
my torque amounts which are take from turbine are too big .
what can i do??
how did you figure out your problem?

May 27, 2013, 15:40
#125
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 Originally Posted by enry Hi, yes, of course, T is torque per unit area. I wrote a UDF in order to get the time average torque, that FLUENT can't give you. Bye.
hi enry
i had simulated a wind turbine using fluent and now i want to calculate the power out put
i,m using this formula: p=torque (NM) *omega(rpm)*2*pi /60
and my rotation axis is y and my center of rotation is (0,0,0).i had set my moment center on (0,0,0) too.
the amount of this power output is 10 times bigger than real results.

what can i do
would you plz help me??

Last edited by niloogh; May 27, 2013 at 16:47.

 May 27, 2013, 16:06 #126 New Member   bhushan patil Join Date: May 2012 Posts: 19 Rep Power: 7 i thought u r formula for calculating power is worng ..use............... power= cp /(1/2 * raho*A*Vinfi ^3)

May 27, 2013, 16:45
#127
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 Originally Posted by p.bhushan2727@gmail.com i thought u r formula for calculating power is worng ..use............... power= cp /(1/2 * raho*A*Vinfi ^3)
tnx dear
would you plz what you mean of "cp" ,"raho" and the other parameters
in addition i,m using fluent for my simulation.

 May 28, 2013, 01:17 #128 New Member   bhushan patil Join Date: May 2012 Posts: 19 Rep Power: 7 HERE CP=Coefficeint of power , raho= dencity of liquid for water =1000 for air=1.998, Vinfi = inlet velocity kkkkkkask if u need any help

May 28, 2013, 05:10
#129
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Quote:
 Originally Posted by p.bhushan2727@gmail.com HERE CP=Coefficeint of power , raho= dencity of liquid for water =1000 for air=1.998, Vinfi = inlet velocity kkkkkkask if u need any help
tnx dear
what is the amount of cp??
can i find it in fluent results????

 May 10, 2014, 17:01 #130 New Member   shafqat Join Date: Apr 2014 Posts: 8 Rep Power: 5 hi....can u please tell me why i get negative cm all the time...i have used tri meshing in icm cfd and sliding meshing technique....

May 12, 2014, 00:50
#131
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bhushan patil
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Quote:
 Originally Posted by shafqat hi....can u please tell me why i get negative cm all the time...i have used tri meshing in icm cfd and sliding meshing technique....
please share your boundry conditions and mesh file here at images of it then we will move forward

May 14, 2014, 18:53
#132
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shafqat
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i am using ke realizable enhancement wall treatment ........for reference values i use swept area in area and length of turbine in length
Attached Images
 mesh.jpg (41.5 KB, 38 views) mesh1.jpg (42.0 KB, 38 views)

 August 1, 2014, 01:58 CFD of propeller #133 New Member     M Mohsin Iqbal Join Date: Jan 2014 Location: National University Sciencies & Technology, Pakistan Posts: 16 Rep Power: 5 Hi i am doing CFD of aircraft propeller. i want to know torque which i got from fluent is ok ???? thrust force which i got from fluent is ok ????? or there is need to calculate thrust by momentum equation for it.. . . . . i.e T = [ MASS FLOW RATE * (Ve - Vi ) ] looking forward. thanks