Static pressure behind a vehicle

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Caito
13
Joined: Tue Jun 16, 2009 4:30 am
Location: Switzerland

Static pressure behind a vehicle

Post by Caito » Mon Feb 12, 2018 2:40 pm

Hi all,


I know that usually behind a moving a vehicle there's a pressure lower than atmospheric.

Do you have any idea how much, or how to calculate? I'm looking mostly into trucks (let's say a flat back) rather than racecars.

I've found nice plots but with no absolute values.
Image

Thanks for your help!
Caito
Come back 747, we miss you!!

Greg Locock
157
Joined: Fri Jun 29, 2012 11:48 pm

Re: Static pressure behind a vehicle

Post by Greg Locock » Tue Feb 13, 2018 4:45 am

In the example, the pressure is probably dark blue = ambient-.2*1/2*rho*v^2

e36jon
26
Joined: Mon Apr 25, 2016 1:22 am
Location: California, USA

Re: Static pressure behind a vehicle

Post by e36jon » Sat Feb 17, 2018 6:25 pm

Greetings Caito

If big truck aero is an interest area you would really dig "Aerodynamics of Road Vehicles" by Hucho. Large vehicle aero gets a bunch of coverage (buses, trains too.). And in general it is a superb text on aero, if a bit dated. (I don't know if they have revved the edition since my copy which was published in 1987.)

Here in the U.S. there has been (finally) quite a bit of movement recently on aero devices for semis, so we are seeing things like flush wheel covers, under trailer 'barge-boards', and even foldable tapered tail fairings... (All of which are covered in the book. Nothing new under the sun?)

Good luck with your project!

Jon

Caito
13
Joined: Tue Jun 16, 2009 4:30 am
Location: Switzerland

Re: Static pressure behind a vehicle

Post by Caito » Wed Feb 28, 2018 1:31 am

Thanks for the replies!!
Come back 747, we miss you!!