Building an HPV Fairing

[trebuchet03]

Update above (this page)

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[trebuchet03]

Updates in post above... Good and Bad.... We're on the good side of things now
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[Cd]

Originally Posted by trebuchet03

FloWorks says .09

FLUENT (we've since meshed a model for FLUENT) says .086

Both at 30mph (or maybe it was 20 - I'll have to double check).

It sounds freaking low, but - max Reynolds number = 184. Not 184 thousand, just 184. We'll get scale wind tunnel testing soon

How does FLUENT compare to FloWorks in ease of use ?

Point zero eighty six. Slick !

I wonder how that this would translate to a full size car if the shapes were identical. I know that the frontal area would change, but how is the .Cd value changed when a shape such as yours is scaled up ?

[trebuchet03]

Originally Posted by .Cd

How does FLUENT compare to FloWorks in ease of use ?

Point zero eighty six. Slick !

I wonder how that this would translate to a full size car if the shapes were identical. I know that the frontal area would change, but how is the .Cd value changed when a shape such as yours is scaled up ?

Fluent is considered to be more robust and more accurate - but, it's not as user friendly. You need to use Gambit (another piece of software) to create the fluid mesh which, if you don't know what you're doing, will fail.

Floworks is much faster to setup - there's a nice GUI and it automatically makes the wind tunnel and creates the mesh.

If you don't know what a mesh is.... A mesh creates discrete points in space for the solver to use. Otherwise, it would have to solve an infinite matrix of equations. If you ever see CFD with nice smooth lines/color gradients - that's interpolated data to connect the dots on the mesh

As for scale up... I can do a run tonight and tell you All one would have to do is run the test at a higher velocity (as if you modeled scaled down). What overall dimensions do you want? Just give me a width and I'll scale everything up proportionally. Theoretically, cD shouldn't change very much - but Reynolds number will (which could mean some of the flow goes turbulent)...

[AndrewJ]

A quick question for clarity's sake.

If I remember correctly you previously said that your CFD program doesn't compute the Cd in ground effect, right?

So what will the Cd be with the ground effect?

[Christopher Jordan]

How very labor intensive! Congrats! I am in awe- mine went through similar forming, but I had no idea of how much time and labor went into it- when I got it in 2005 I slaapped the Pod together in 2 months maximum.

[trebuchet03]

Originally Posted by AndrewJ

A quick question for clarity's sake.

If I remember correctly you previously said that your CFD program doesn't compute the Cd in ground effect, right?

So what will the Cd be with the ground effect?

No clue :/ I'd love to know how to make a rolling wind tunnel for CFD - but I don't know how If anyone knows (and I know it's possible) - please let me know

[trebuchet03]

Originally Posted by Christopher Jordan

How very labor intensive! Congrats! I am in awe- mine went through similar forming, but I had no idea of how much time and labor went into it- when I got it in 2005 I slaapped the Pod together in 2 months maximum.

We just passed to one month date for actual construction I'll have an update later after we pull the second attempt of the first part out

[trebuchet03]

Another update above Go check it out

[pawilkes]

I was at competition last year, mostly as a spectator. my grad school research was on designing a hand-powered cycle that the HPV team from Wisconsin based their design on last year. anyhow, i was amazed at the fairing UCF put together last year and i guess you're just building on that. good luck at competition and enjoy Wisconsin's spring conditions.