Air density temperature (in kelvin) polynomial function

• Oct 11, 2023

• #2

rb1957

Aerospace

Apr 15, 2005

15,698

curve fit to the data. BTW, what is "air density temperature" ? "air density" I understand (but not in degrees Kelvin) "air temperature" in degrees kelvin makes sense. And of course degrees kelvin is the same as degrees celsius with a constant term added.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

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• Oct 11, 2023

• #3

Latexman

Chemical

Sep 24, 2003

6,928

What's wrong with the ideal gas equation?

PV = nRT

and

[ρ] = P(MW)/RT.

IMHO, flow calculations are not so exact to justify the complexity of a polynomial fit to air density.

Good Luck,
Latexman

 

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• Oct 11, 2023

• #4

rb1957

Aerospace

Apr 15, 2005

15,698

doesn't work well with the atmosphere, as density changes with altitude.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

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• Oct 11, 2023

• #5

IRstuff

Aerospace

Jun 3, 2002

44,442

Just a nitnoid here; the SI unit for absolute temperature is the kelvin, no degrees. Degrees Celsius is the relative temperature unit.

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• Oct 11, 2023

• #6

3DDave

Aerospace

May 23, 2013

10,767

Kelvin - earned the capital K.

 

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• Oct 11, 2023

• #7

IRstuff

Aerospace

Jun 3, 2002

44,442

the unit is the kelvin (K)

https://www.nist.gov/pml/owm/si-units-temperature

even NIST's page is ambiguous. see page 4 of

https://physics.nist.gov/cuu/pdf/sp811.pdf

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• Oct 11, 2023

• #8

SWComposites

Aerospace

Nov 6, 2000

3,376

OP - just Google “air density vs temperature”

 

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• Oct 12, 2023

• #9

rb1957

Aerospace

Apr 15, 2005

15,698

yeah, I read the question from my perspective. But I don't think he means that. But rather changes at sealevel.

So Latexman, or SWC

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

 

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