Blade torque

SAH2006 · April 12, 2010, 17:39

Hi everybody, I am simulating a wells turbine using MRF. The problem is when i calculate the blade torque (either using wall data or monitor boundaries) it gives a value very close to zero!!!! after investigations i found that one blade surface gives a negative torque and the other surface gives a value very close to the first surface but the torque is positive!!!! therefore the net blade torque almost equals zero. Can someone help me solving this problem????

nomad · May 19, 2010, 19:46

Can you describe your problem setup?

SAH2006 · May 25, 2010, 19:25

I have established the mesh and assigned wall boundaries to the blade (suction side, pressure side, hub and tip) and then i monitored these walls during the solution. the problem now is the value of the calculated torque. The torque does not change as I change the flow velocity. When i double the flow velocity the torque remains almost the same!!!!! can anyone help me to fix this problem???

JBeilke · May 26, 2010, 05:28

Are you rotating your turbine in any way?

SAH2006 · May 26, 2010, 14:14

I am using mrf. I divided the mesh into two domains (materials). the first domain is the piping before and after the The turbine and the second domain contains the turbine blades. the domain containing the blades rotates at 2500 rpm while the other one is stationary. I meshed the geometry using pro-amm. I assigned a negative rotational speed (-2500) to the walls above the blades to maintain the turbine casing of the rotating domain stationary relative to the blades. the turbulence model is k-epsilon high Reynolds number.

nomad · May 26, 2010, 16:35

You need to create an in-place interface between the rotating and non-rotating regions. The interface would ensure that information gets transferred from the rotating region to the non-rotating region. This way you would only need to rotate the region containing the blades.
Also make sure your rotation axis is along the axis of the turbine.

Are you using starccm+?

SAH2006 · May 26, 2010, 17:08

I am using Star CD and I already established an interface between the rotating and the stationary regions. my axis of rotation is the default z-axis. is the values of Txtorq ,Tytorq , Tztorq in the .erd file are with respect to Cartesian coordinate system?

April 12, 2010, 17:39	Blade torque	#1
SAH2006 New Member Sameh Join Date: Apr 2010 Posts: 9 Rep Power: 16	Hi everybody, I am simulating a wells turbine using MRF. The problem is when i calculate the blade torque (either using wall data or monitor boundaries) it gives a value very close to zero!!!! after investigations i found that one blade surface gives a negative torque and the other surface gives a value very close to the first surface but the torque is positive!!!! therefore the net blade torque almost equals zero. Can someone help me solving this problem????

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May 19, 2010, 19:46		#2
nomad Member John Join Date: Aug 2009 Posts: 92 Rep Power: 17	Can you describe your problem setup?

May 25, 2010, 19:25		#3
SAH2006 New Member Sameh Join Date: Apr 2010 Posts: 9 Rep Power: 16	I have established the mesh and assigned wall boundaries to the blade (suction side, pressure side, hub and tip) and then i monitored these walls during the solution. the problem now is the value of the calculated torque. The torque does not change as I change the flow velocity. When i double the flow velocity the torque remains almost the same!!!!! can anyone help me to fix this problem???

May 26, 2010, 05:28		#4
JBeilke Senior Member Joern Beilke Join Date: Mar 2009 Location: Dresden Posts: 539 Rep Power: 20	Are you rotating your turbine in any way?

May 26, 2010, 14:14		#5
SAH2006 New Member Sameh Join Date: Apr 2010 Posts: 9 Rep Power: 16	I am using mrf. I divided the mesh into two domains (materials). the first domain is the piping before and after the The turbine and the second domain contains the turbine blades. the domain containing the blades rotates at 2500 rpm while the other one is stationary. I meshed the geometry using pro-amm. I assigned a negative rotational speed (-2500) to the walls above the blades to maintain the turbine casing of the rotating domain stationary relative to the blades. the turbulence model is k-epsilon high Reynolds number.

May 26, 2010, 16:35		#6
nomad Member John Join Date: Aug 2009 Posts: 92 Rep Power: 17	You need to create an in-place interface between the rotating and non-rotating regions. The interface would ensure that information gets transferred from the rotating region to the non-rotating region. This way you would only need to rotate the region containing the blades. Also make sure your rotation axis is along the axis of the turbine. Are you using starccm+?

May 26, 2010, 17:08		#7
SAH2006 New Member Sameh Join Date: Apr 2010 Posts: 9 Rep Power: 16	I am using Star CD and I already established an interface between the rotating and the stationary regions. my axis of rotation is the default z-axis. is the values of Txtorq ,Tytorq , Tztorq in the .erd file are with respect to Cartesian coordinate system?