Speed of sound in a real gas?

[KernOily]

Can one of you point me to a reference to determine the speed of sound in a real gas? A=sqrt(kRT) only works for real gases. I am *significantly* out of the real category in this particular problem. Thanks!

Thanks!
Pete

 

[25362]

The NIST chemistry webbook gives speed of sound for many (pure) gases at varying P, T conditions.

 

[sailoday28]

sound speed=sqrt dp/drho under isentropic conditions.

 

[MortenA]

NIST data is only for pure components.

Speed of sound depends on many parameters. You should use special software if this is a gas mixture and the value require high accuracy.

Best regards

Morten

 

[sailoday28]

For homogeneous gas mixtures the sound speed may be calculated from sqrt dp/drho isentropic
if an equations of state and specific heat at a low pressure is available.

 

[KernOily]

sailoday28 said:
>For homogeneous gas mixtures the sound speed may be >calculated from sqrt dp/drho isentropic
>if an equations of state and specific heat at a low >pressure is available.

Being a dumb BSME, I can't handle differential elements too well, therefore sqrt (dP/drho) isn't too useful to me. I need something I can place into a spreadhseet. I have access to SRK and other EOS's via simulation software, e.g. HYSYS. Can you get me to the next step? Thanks!

Thanks!
Pete

 

[sailoday28]

For single phase fluid, the sound speed^2=-v^2(dp/dv) under isentropic conditions where
v specific vol
p pressure

BUT dp/dv isentropic= gamma*dp/dv isothermal
where gamma = Cp/Cv

(sound speed/v)^2=-gamma*dp/dv isothermal
Given a pressure and temp (or v), an equation of state and gamma, the sound speed is readilly calculated.

If need be, gamma may be calculated if either Cp or Cv is known at low pressures.