# Aeroengines/Fluid Mechanics - Steady Flow

1. Jan 26, 2015

### JRS192

1. The problem statement, all variables and given/known data
See Fig.2.4a, let the gases flowing through the nozzle control volume be perfect with Cp = 1.004kJ/kg.K

Determine V9 if T5 = 1000K, T9 = 670K and V5 = 120ms^-1.

2. Relevant equations
I've detailed the equations in the attached pdf for clarity.

3. The attempt at a solution
See attached pdf. The question paper has the answer as 822.8m/s, but I'm consistently getting 120m/s. Where am I going wrong?

Thank you

#### Attached Files:

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• ###### doc00586420150126151206.pdf
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2. Jan 26, 2015

### SteamKing

Staff Emeritus
You've confused the universal gravitational constant G for the acceleration due to gravity on earth, gc.
It's not clear why you don't understand the distinction between these two constants.

3. Jan 26, 2015

### JRS192

Hi SteamKing,

Thanks for that. I did some research and everything directed me to that figure, even to the point of using gc...

4. Jan 26, 2015

### SteamKing

Staff Emeritus
I doubt that. You have misinterpreted something in what you read.

The universal gravitational constant G (which is invariably capitalized) is typically used to find the force of gravitational attraction between two masses, as described by the formula

F = Gm1m2/r2

G is used more often in physics type calculations. G also has some rather unusual units: G = 6.67*10-11 m3/kg-s2

The acceleration due to gravity on earth, gc, which is invariably lower case, is typically commonly found in engineering type calculations, moreso than G.

5. Jan 26, 2015

### JRS192

Thank you for your help.

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