# Thermodynamics - Steady State Nozzle, find area of inlet/exit

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1. Oct 25, 2015

### leafjerky

1. The problem statement, all variables and given/known data
In a jet engine, a flow of air at 1000 K, 200 kPa, and 40 m/s enters a nozzle, where the air exits at 500 m/s and 90 kPa. What is the exit temperature, inlet area, and exit area, assuming no heat loss?

2. Relevant equations
min = mout = m
where m = mass air flow
dE/dt cv = Qcv - Wcv + Σmin(h+ (Vin/2)2 + gz) - Σmout(h+ (Vout/2)2 + gz)

exit area:
m = ρAV
where m = mass air flow, ρ = density, A = area, V = velocity

3. The attempt at a solution
I've already solved for the exit temperature to be 890 K. I just need to know how to find the exit/inlet areas.

2. Oct 25, 2015

### SteamKing

Staff Emeritus
If there is no mass addition between the inlet and the exit, then doesn't continuity apply?

I don't know if you will be able to find the individual areas, but you should be able to calculate an area ratio between the inlet and exit.

3. Oct 25, 2015

### leafjerky

In our problems with nozzles, I believe we are assuming the following:
• closed system
• steady state (de/dt = 0)
• W = 0
• Q = 0
• PE = 0
I have emailed my teacher regarding the problem with the areas. I figured she must have left m out on accident. I just wanted to come on here and make sure. Thanks for your help as always SteamKing

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