I an working on a problem in the text "Mechanics and Thermodynamics of Propulsion" 2e. The problem states a perfect gas with molecular weight M=20 and a specific heat ratio of Y=1.2 expands adiabatically in steady flow from a pressure of 6MPa, a temperature of 3000K, and a velocity of 200 m/s to a final pressure of 0.101 MPa. If the final temperature is 1800K and the final velocity is negligible, what is the work done(adsbygoogle = window.adsbygoogle || []).push({});

I know that adiabatic means no heat in or out of the system so dq=0

Y=cp/cv and cp=cv+R

dq=de+dw

My attempt:

First i find R=8314.3/20=415.715

then i find cv by cv=R/(Y-1) cv=2078.58

thus dw= (-de) where de=cv(T2-T1)

my answer for the work done is 2494.29 kJ/kg however the books answer is 3013 Kj/kj

what am i doing wrong?

thanks for your help

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# Homework Help: Archived Adiabatic expansion in a steady flow question

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