Total time for a transient rotor stator simulation

saisanthoshm88 · October 28, 2012, 12:40

I'd like to run a transient rotor stator simulation of a cooling fan and I'm applying a time step based on the rpm of the fan and the mesh size on the rotor stator interface such that the courant number would be some thing between 1 to 3.

I'm using the Mesh Motion option to do this.

Could some one please let me know how to choose the total time required for the simulation.

Far · October 28, 2012, 13:11

Refer to page 384

http://hikwww2.fzk.de/hik/orga/hlr/A.../Tutorials.pdf

vicarious · October 28, 2012, 14:28

The total time steps per revolution is variable and you can choose different ones (Since your CFL number does not increase too much), but one of the most important parameters is the number of blades (and the rotating speed of the configuration). For example for a cascade of 5 rotor and stator blades, 250 time steps is sufficient for simulation one rotor revolution.
Then you calculate the tangential speed of rotor (U=r*RPM) and the time step required for the simulation can be calculated from Delta(t) = L/(n*U).
r:The hub to tip radius.
n:Total time steps per revolution.
L:The cascade length.

Hope It's helpful,
Best regards.

October 28, 2012, 12:40	Total time for a transient rotor stator simulation	#1
saisanthoshm88 Senior Member --------- Join Date: Oct 2010 Posts: 303 Rep Power: 17	I'd like to run a transient rotor stator simulation of a cooling fan and I'm applying a time step based on the rpm of the fan and the mesh size on the rotor stator interface such that the courant number would be some thing between 1 to 3. I'm using the Mesh Motion option to do this. Could some one please let me know how to choose the total time required for the simulation. __________________ Best regards, Santhosh.

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October 28, 2012, 13:11		#2
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	Refer to page 384 http://hikwww2.fzk.de/hik/orga/hlr/A.../Tutorials.pdf

October 28, 2012, 14:28		#3
vicarious Member Pedram Mojtabavi Join Date: Apr 2011 Location: Iran Posts: 66 Rep Power: 15	The total time steps per revolution is variable and you can choose different ones (Since your CFL number does not increase too much), but one of the most important parameters is the number of blades (and the rotating speed of the configuration). For example for a cascade of 5 rotor and stator blades, 250 time steps is sufficient for simulation one rotor revolution. Then you calculate the tangential speed of rotor (U=rRPM) and the time step required for the simulation can be calculated from Delta(t) = L/(nU). r:The hub to tip radius. n:Total time steps per revolution. L:The cascade length. Hope It's helpful, Best regards.