Conversion from rpm to 1/s ?

#1 Опубликовано: 11.04.2018 10:16:36

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Hi,

i calculated the Reynoldsnumber where i need the revolutions per minute. What struck me was the conversion from rpm to 1/s -> 60rpm = 1 rps = 1 s^-1. According to smath 60rpm = 6,28 s^-1.

Is there a bug or are i'm doing the math wrong?

thanks a lot!

#2 Опубликовано: 11.04.2018 10:38:51

Davide Carpi

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please read here (SS-2395) (you can vote and comment it), here or here (and other...)

base unit of a revolution is coded as 2pi radians (not 1), hence the multiplication factor.

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Arie 11.04.2018 10:42:00

#3 Опубликовано: 11.04.2018 10:41:00

Arie

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This is because the standard unit in SMath for rotation is radian = 2*pi which is ~6.28. If you look at the definition of rpm it is pi/30 1/s or 2*pi/60.

In order to get the right result you need to divide by 2*pi. What i would suggest is creating your own unit for RPMs as done in the attached.

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Edit: Davide beat me to it.

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#4 Опубликовано: 11.04.2018 11:42:37

Jean Giraud

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