Fluent (ANSYS12) UDF Help, PLEASE! Urgent!

ANITIX87 · October 31, 2010, 20:31

Hi, all.

I ran my experiment, with the UDFs. Everything seems to be working, and I have no errors. However, I have three problems.

1) My coefficient of Lift and coefficient of Drag seem to be switched around. I expect CL = 1.2 and CD = 0.3, and my experiment results in CL = 0.2 and CD = 1.3 when I run more than 100 iterations.

2) I cannot get motion in my animation. Even when running 500 iterations, I played back my animation and the windmill didn't revolve at all. Anybody have any feedback or recommendations?

3) Is there any way to find the mass of my turbine? It is its own geometry (called "turbine" in fluent) but I don't know its mass for modifying my UDF's equation. Is the equation I am using sufficient, by the way? It calculated the force on each face, and then uses F = M*A to calculate the acceleration of the windmill. But since it's angular velocity, should I be using a different equation?

Thanks

TIS

mamyjooooon · April 12, 2011, 03:55

Hi Antonis
I want to solve flow in a radial turbine wheel(with high RPM).
Because the flow work is done on the blades to make the blades rotating,I decided to use dynamics mesh with 6dof.
i want to solve flow in a radial turbine wheel(with high RPM).
Because the flow work is done on the blades to make the blades rotating,I decided to use dynamics mesh with 6dof.
I have no correct data about my udf file?
can you help me?

April 12, 2011, 03:55		#22
mamyjooooon New Member mamadreza Join Date: Mar 2011 Posts: 22 Rep Power: 15	Hi Antonis I want to solve flow in a radial turbine wheel(with high RPM). Because the flow work is done on the blades to make the blades rotating,I decided to use dynamics mesh with 6dof. i want to solve flow in a radial turbine wheel(with high RPM). Because the flow work is done on the blades to make the blades rotating,I decided to use dynamics mesh with 6dof. I have no correct data about my udf file? can you help me? Last edited by mamyjooooon; April 16, 2011 at 00:45.

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October 31, 2010, 20:31		#21
ANITIX87 New Member Antonis Join Date: Oct 2010 Posts: 13 Rep Power: 15	Hi, all. I ran my experiment, with the UDFs. Everything seems to be working, and I have no errors. However, I have three problems. 1) My coefficient of Lift and coefficient of Drag seem to be switched around. I expect CL = 1.2 and CD = 0.3, and my experiment results in CL = 0.2 and CD = 1.3 when I run more than 100 iterations. 2) I cannot get motion in my animation. Even when running 500 iterations, I played back my animation and the windmill didn't revolve at all. Anybody have any feedback or recommendations? 3) Is there any way to find the mass of my turbine? It is its own geometry (called "turbine" in fluent) but I don't know its mass for modifying my UDF's equation. Is the equation I am using sufficient, by the way? It calculated the force on each face, and then uses F = M*A to calculate the acceleration of the windmill. But since it's angular velocity, should I be using a different equation? Thanks TIS