determine rpm value of turbine

ruya · April 23, 2013, 06:22

hi friends.
I have a problem that how can determine value of turbine flow meter. Firstly I gave an arbitrary value to rotor such as 11 rad/s then I calulated torque with cfd- post but I don't know that I move on or how can ı compare torque and rpm that I gave.
I want to help. Thanks.

Far · April 24, 2013, 15:26

You can draw the graph of Cp VS torque or rpm and compare it to the experimental trends.

ruya · April 30, 2013, 12:39

thanks but I haven't got experimental results. I change my procedure. I prefer that I obtain volumetric flow according to given rpm. but I have a problem because volumetric flow rate doesn't change according to value of rpm. This stiuation is impossible and rpm doesn't effect flow rate.

stuart23 · April 30, 2013, 19:19

You have three variables in your simulation that you are trying to either control or evaluate: mass flow rate (or pressure ratio), turbine speed and load.

On a dyno, you would specify the MFR and load to get the resulting speed, however to do this in a CFD simulation requires a UDF to modify the rotational speed depending on the torque at the turbine axis. This is rather complicated and not recommended.

An easier approach is to set the rotational speed and MFR then measure the resulting torque. Once you graph these results, you will get the same figure as if you had dyno tested the turbine.

Stu

April 23, 2013, 06:22	determine rpm value of turbine	#1
ruya New Member ruya Join Date: Apr 2013 Location: TURKEY Posts: 4 Rep Power: 13	hi friends. I have a problem that how can determine value of turbine flow meter. Firstly I gave an arbitrary value to rotor such as 11 rad/s then I calulated torque with cfd- post but I don't know that I move on or how can ı compare torque and rpm that I gave. I want to help. Thanks.

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April 24, 2013, 15:26		#2
Far Super Moderator Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,553 Blog Entries: 6 Rep Power: 54	You can draw the graph of Cp VS torque or rpm and compare it to the experimental trends.

April 30, 2013, 12:39		#3
ruya New Member ruya Join Date: Apr 2013 Location: TURKEY Posts: 4 Rep Power: 13	thanks but I haven't got experimental results. I change my procedure. I prefer that I obtain volumetric flow according to given rpm. but I have a problem because volumetric flow rate doesn't change according to value of rpm. This stiuation is impossible and rpm doesn't effect flow rate.

April 30, 2013, 19:19		#4
stuart23 Senior Member Stuart Buckingham Join Date: May 2010 Location: United Kingdom Posts: 267 Rep Power: 25	You have three variables in your simulation that you are trying to either control or evaluate: mass flow rate (or pressure ratio), turbine speed and load. On a dyno, you would specify the MFR and load to get the resulting speed, however to do this in a CFD simulation requires a UDF to modify the rotational speed depending on the torque at the turbine axis. This is rather complicated and not recommended. An easier approach is to set the rotational speed and MFR then measure the resulting torque. Once you graph these results, you will get the same figure as if you had dyno tested the turbine. Stu