diameter and max velocity

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wangbungal
Posts: 3
Joined: Sun Jan 29, 2012 5:02 am

diameter and max velocity

Post by wangbungal »

I need help with these problems as I am using the calculator, I am having hard time what formula did they use,

# 1 Air at std conditions flows through a 2 std type M copper tube. What is the max velocity allowable for laminar conditions to exist? ( std conds, air can be treated as incompressible)

# 2 a fuel line is to convey octane over a distance of 10 m. the reqd flow rate is 0.0085 m^3/s and the allowable pres. drop is 75 kpa. select an appropriate line size if drawn copper is used.


on the 1st question, I just want to know how is the velocity is determined,

2nd question, the words required and allowable is throwing me off,

thanks for taking ur time to look on my problems!
PipeFlowCalcs
Posts: 57
Joined: Sat Sep 17, 2011 8:50 am

Re: diameter and max velocity

Post by PipeFlowCalcs »

On every calculator you can find theory button which will open web page with theory and equation used.
To have laminar conditions Re number must be lower that 2320, so using Re number calculator you can check the velocity.
Here is Report to Q1:
Reynolds number calculator


1. diameter (D):
D : 2 in

2. velocity (V):
V : 0.641 m/s

3. volumetric flow rate (q):
q : 4.677109 m3/h

4. mass flow rate (w):
w : 0.0015926397 kg/s

5. density (ρ):
ρ : 1.2258638 kg/m3

6. kinematic viscosity (ν):
ν : 1.4030922E-005 m2/s

7. dynamic viscosity (μ):
μ : 17.2E-006 Pas

8. pressure (p):
p : 101325 Pa

9. tempearture (T):
T : 288 K

10. gas constant (R):
R : 287 J/kgK

11. Reynolds number (Re):
Re : 2320.7883


And for Q2:

Pipe pressure drop calculator

1. volume flow rate (q):
q : 0.0085 m3/s

2. weight flow rate (w):
w : 30599.977 kg/h

3. pipe length (L):
L : 10 m

4. pipe diameter (D):
D : 45.75 mm

5. pipe roughness (kr):
kr : 0.1 mm

6. density (ρ):
ρ : 1000 kg/m3

7. kinematic viscosity (ν):
ν : 1.006 mm2/s

8. dynamic viscosity (μ):
μ : 0.0010060001 Pas

9. K factor - minor lossed coefficient (K ):
K : 0.0

10. velocity (V):
V : 5.1706696 m/s

11. cross section area (A):
A : 1643.8877 mm2

12. friction coefficient (f):
f : 0.023957262

13. Reynolds number (Re):
Re : 235147.27

14. boundary layer (δ):
δ : 0.057244822 mm

15. pressure on the pipe start (p1):
p1 : 6 bar

16. pressure on the pipe end (p2):
p2 : 5.299981 bar

17. pressure drop (p1-p2):
p1-p2 : 70.00188 kPa
Pipe flow calculations - free fluid flow calculators
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