hii, I’m doing an analysis of a small RC powered aircraft with a wingspan of 1.2m. On doing its analysis, the value of Cl and Cd is much higher (Cl is almost twice than the predicted value of using xflr5).
Can anyone please help me finding the problem with CAD or mesh which can help me get accurate results
link of project is- SimScale
thanks.
Hi there, thank you for reaching out to us!
This is a common question of many users, and my first comment is to always keep in mind that 3D and 2D are expected to have different results.
In order to get as reliable results as possible with your 3D model, make sure to create a good mesh.
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Take into consideration the y+:How to Control and Analyze Y+ in Meshing Simulation | SimScale
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Make sure you have a good mesh quality: How to Control and Analyze Y+ in Meshing Simulation | SimScale
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You can use a similar tutorial as reference: Incompressible Turbulent Flow Around a Spoiler | SimScale
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Use the correct values for the reference length and area: How To Analyze the Pitch, Lift, and Drag Coefficients | SimScale
For example, I see you are using a reference area of 1 m² in your Results Control set up, which does not seem to be the correct value.
Best regards,
Fillia
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I corrected the reference area and reference length value as you said, but the results are worse then before.
The method that I am using for doing analysis in the one shown in DBF aircraft design workshop. Can you please check again to see what I’m doing wrong
Thanks again
Well, @astiksrivastav, you are far from following Filia advices. In you last simulation (Incompressible 3), your model has ‘slip’ BC. This is not appropriate, as in that case calculations of drag / lift will fail…
AoA of your wings is 0 and negative (rear) and flow is with Ux 20 m/s (no angle to the wind) . This would not help with lift…
Mesh is already huge and you will possibly waste your core-hours on not useful simulations. Perhaps you should try standard mesh first?
I do not see the BL (which should be set to correct Y+) neither.
So far, no good. You are in learning phase and you know already what’s wrong, so take care.
Retsam
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