SimScale CAE Forum

Unsure about force coefficients of a nose cone simulation

Hello, my fsae team asked me to simulate some ideas for a future nose cone. I’ve simulated about 10 models so far, and pretty much all of them (besides some points out of the curve) fell on the -0.3 Cl range. However, one of the models got a Cl of -0.515 and a Cd of 0.302, which is giving me a Cl/Cd of 1,705, which is way higher than all of the other models. Here is the link for the project I’m talking:

Here are some of the other models I tried:

What could explain the large difference in lift? Thanks in advance.

Hello sounds interesting,
but this is a lot of projects, can you please just give us a link to your best solution and one reference simulation.
An idea I have: did you check the ground clearance in the simulation? A few mm can make a huge difference in CL.

Thanks and best regards Sebastian

This was the second most efficient version with -0,355 Cl and 0,359 Cd:

(Nose Cone #4)

They all the pretty much the same ground clearance too (about 180mm). I think it’s really weird how it has a larger frontal area but smaller Cd

Hi i think I found the reason when arranging the images side by side.

I think this explains the differences pretty well. You can see that even with a smaller frontal area the more blunt-body does create more resistance and therefore a bigger area of high pressure, while the pressure of the backside is nearly the same.

Also you can see that the high-pressure region for nosecone #4 is more at the top of the nose cone and therefore creating the high CL. in comparison to the more symmetric body.

I hope that gives you the insights you need. Also, I would suggest you to always use 1m² (0.5 for half-car) as a reference area so that only the aerodynamic changes are represented in the force coefficients.

Best regards
Sebastian

Thank you for the insight!