Aeroengines/Fluid Mechanics - Steady Flow

  • Thread starter JRS192
  • Start date
  • #1
7
0

Homework Statement


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.

Homework Equations


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

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
 

Attachments

Answers and Replies

  • #2
SteamKing
Staff Emeritus
Science Advisor
Homework Helper
12,796
1,668
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
7
0
Hi SteamKing,

Thanks for that. I did some research and everything directed me to that figure, even to the point of using gc...
 
  • #4
SteamKing
Staff Emeritus
Science Advisor
Homework Helper
12,796
1,668
Hi SteamKing,

Thanks for that. I did some research and everything directed me to that figure, even to the point of using gc...
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
7
0
Thank you for your help.
 

Related Threads on Aeroengines/Fluid Mechanics - Steady Flow

Replies
4
Views
469
Replies
6
Views
684
  • Last Post
Replies
0
Views
4K
Replies
3
Views
3K
  • Last Post
Replies
1
Views
2K
Replies
2
Views
968
Replies
6
Views
5K
Replies
1
Views
223
Replies
11
Views
633
Top