Cl history for pitching airfoil(i.e at changing AoA)

ned.musab · October 26, 2017, 12:51

Hello everyone...
I need your views/ideas. I am having serious problem and got stuck and dont know how to encounter that issue. The master's thesis submission date is around the corner.

My question is about pitching airfoil

In pitching airfoil case the angle of attack changes with time. In Solve/Monitors, we can plot CL history but that is for some 'fixed' angle of attack (as there is no option there to upload a UDF file).
So, I want save CL values history at changing angle of attack.

Can anybody tell me how to get CL history in this case?

Really appreciate your views.

Thanks in advance

ksingh · October 30, 2017, 09:57

You can monitor/write Cd and Cl before running simulation. BTW, which software you are using?

ned.musab · November 4, 2017, 06:56

Hi...
Ansys(Fluent)...That i already know but in monitor tab you can just plot cl or cd vs time flow at single aoa not for pitching airfoil case.

I think you didn't get what i am trying to plot.

Rephrasing my question again for everyone for proper understanding.

I just want to get CL values at 'different' aoa (i.e data history in output file) using Fluent. Right now i am getting values of cl vs time flow at single(let say 0 degree) aoa using tab solve>monitors....

Can anyone tell me that in Ansys(Fluent) do i need to use Macro named 'DEFINE_OUTPUT_PARAMETER' to get history of the data required to plot cl vs aoa.
and how the lift force will be calulatd for this (i.e pitching airfoil) case?

ksingh · November 10, 2017, 18:57

Hi Dear!!
I am working on pitching airfoil since last six months. And I would re-emphasized my previous words. You can get time Vs Cd and Cl if you are creating monitors for Lift and Drag before running simulation. You can convert data from time to AOA using the equation which you specified in ur UDF for pitching motion. In short time history will give you AOA.

ned.musab · November 11, 2017, 05:08

Hi..
I already know above idea to get AoA that you mentioned in your post.
It will give you correct values for time vs aoa only using pitching equation but if you plot cl vs aoa then it will be incorrect.
Reason is that we got Cl values history just for a single aoa.
Hope its clears you.

ksingh · November 11, 2017, 10:08

Hi Dear!!
Either your question is not clear to me or your methodology to change AOA. You must be using UDF to give some pitching movement to airfoil and your airfoil is continuously in motion. If it is so, how do you get Cl corresponding to single AOA? If not, can you elaborate how you changed AOA?

October 26, 2017, 12:51	Cl history for pitching airfoil(i.e at changing AoA)	#1
ned.musab New Member musab Join Date: Oct 2017 Posts: 11 Rep Power: 8	Hello everyone... I need your views/ideas. I am having serious problem and got stuck and dont know how to encounter that issue. The master's thesis submission date is around the corner. My question is about pitching airfoil In pitching airfoil case the angle of attack changes with time. In Solve/Monitors, we can plot CL history but that is for some 'fixed' angle of attack (as there is no option there to upload a UDF file). So, I want save CL values history at changing angle of attack. Can anybody tell me how to get CL history in this case? Really appreciate your views. Thanks in advance

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October 30, 2017, 09:57		#2
ksingh Member Kuldeep Join Date: Mar 2016 Posts: 33 Rep Power: 10	You can monitor/write Cd and Cl before running simulation. BTW, which software you are using?

November 4, 2017, 06:56		#3
ned.musab New Member musab Join Date: Oct 2017 Posts: 11 Rep Power: 8	Hi... Ansys(Fluent)...That i already know but in monitor tab you can just plot cl or cd vs time flow at single aoa not for pitching airfoil case. I think you didn't get what i am trying to plot. Rephrasing my question again for everyone for proper understanding. I just want to get CL values at 'different' aoa (i.e data history in output file) using Fluent. Right now i am getting values of cl vs time flow at single(let say 0 degree) aoa using tab solve>monitors.... Can anyone tell me that in Ansys(Fluent) do i need to use Macro named 'DEFINE_OUTPUT_PARAMETER' to get history of the data required to plot cl vs aoa. and how the lift force will be calulatd for this (i.e pitching airfoil) case?

November 10, 2017, 18:57		#4
ksingh Member Kuldeep Join Date: Mar 2016 Posts: 33 Rep Power: 10	Hi Dear!! I am working on pitching airfoil since last six months. And I would re-emphasized my previous words. You can get time Vs Cd and Cl if you are creating monitors for Lift and Drag before running simulation. You can convert data from time to AOA using the equation which you specified in ur UDF for pitching motion. In short time history will give you AOA.

November 11, 2017, 05:08		#5
ned.musab New Member musab Join Date: Oct 2017 Posts: 11 Rep Power: 8	Hi.. I already know above idea to get AoA that you mentioned in your post. It will give you correct values for time vs aoa only using pitching equation but if you plot cl vs aoa then it will be incorrect. Reason is that we got Cl values history just for a single aoa. Hope its clears you.

November 11, 2017, 10:08		#6
ksingh Member Kuldeep Join Date: Mar 2016 Posts: 33 Rep Power: 10	Hi Dear!! Either your question is not clear to me or your methodology to change AOA. You must be using UDF to give some pitching movement to airfoil and your airfoil is continuously in motion. If it is so, how do you get Cl corresponding to single AOA? If not, can you elaborate how you changed AOA?