Circumferential Mach Average

jp312 · November 11, 2020, 05:14

Hello everyone,

I´m pretty new to Tecplot and CFD simulations in general hence I need your help. I am currently working on Turbomachinery simulations for an airplane Turbofan. In order to evaluate my data I want to display a circumferential average of the mach number for the whole Turbofan.
I don´t know where to start so any advice will be appreciated.

Thank you!

wsfowler · November 19, 2020, 00:23

Are you looking for a line plot as a result? Where the X-Axis is Theta and the Y-Axis is the average Mach at that Theta value?

I believe this can be done, but it will be tricky and would effectively have to be scripted.

You could:
1) Compute a new Theta variable.
2) Create an iso-surface at that defined Theta. This is slightly problematic as you get a bit of a singularity as R approaches zero. And you get an unwanted portion of the iso-surface in the cells that span 360-0 degrees. This can be mitigated with Value Blanking. Alternately you might just use a slice, which passes through the radius and again use value blanking to isolate the region on one side of the center.
3) Extract the iso-surface (or slice)
4) Use Analyze>Integrate>Average to compute the average Mach on the extracted iso-surface and store the result.

Repeat steps 2-4 at various Theta angles.

This could all be scripted using PyTecplot, Tecplot 360's Python API.

I'm sure there are other solutions but this is the one that came to mind. If you have a structured dataset where planes are aligned with theta the process may be much easier.

Scott

jp312 · November 23, 2020, 08:17

Thank you for taking the time to answer my problem.
The way you´re describing it is basically the way I went for in the end.
The only exception is, that I wrote a macro in Ansys CFD-Post that calculates all the variables and exports them to Tecplot, as I found this a lot more intuitive.

Thanks again,
Jan

November 11, 2020, 05:14	Circumferential Mach Average	#1
jp312 New Member Jan Join Date: Nov 2020 Posts: 2 Rep Power: 0	Hello everyone, I´m pretty new to Tecplot and CFD simulations in general hence I need your help. I am currently working on Turbomachinery simulations for an airplane Turbofan. In order to evaluate my data I want to display a circumferential average of the mach number for the whole Turbofan. I don´t know where to start so any advice will be appreciated. Thank you!

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November 19, 2020, 00:23		#2
wsfowler Senior Member Scott Fowler Join Date: May 2009 Posts: 112 Rep Power: 16	Are you looking for a line plot as a result? Where the X-Axis is Theta and the Y-Axis is the average Mach at that Theta value? I believe this can be done, but it will be tricky and would effectively have to be scripted. You could: 1) Compute a new Theta variable. 2) Create an iso-surface at that defined Theta. This is slightly problematic as you get a bit of a singularity as R approaches zero. And you get an unwanted portion of the iso-surface in the cells that span 360-0 degrees. This can be mitigated with Value Blanking. Alternately you might just use a slice, which passes through the radius and again use value blanking to isolate the region on one side of the center. 3) Extract the iso-surface (or slice) 4) Use Analyze>Integrate>Average to compute the average Mach on the extracted iso-surface and store the result. Repeat steps 2-4 at various Theta angles. This could all be scripted using PyTecplot, Tecplot 360's Python API. I'm sure there are other solutions but this is the one that came to mind. If you have a structured dataset where planes are aligned with theta the process may be much easier. Scott

November 23, 2020, 08:17		#3
jp312 New Member Jan Join Date: Nov 2020 Posts: 2 Rep Power: 0	Thank you for taking the time to answer my problem. The way you´re describing it is basically the way I went for in the end. The only exception is, that I wrote a macro in Ansys CFD-Post that calculates all the variables and exports them to Tecplot, as I found this a lot more intuitive. Thanks again, Jan