1. Major and Minor Losses in Pipes
9/24/2012
Major and Minor Losses in Pipes
Trans-Alaska Pipeline System
Length 1287 km, D=1.22 m
ME 322 THERMO-FLUIDS LAB-1
1/18/2019
ME 383 Fluid Mechanics

2. Major and Minor Losses in Pipes
9/24/2012
Major and Minor Losses in Pipes
Energy Considerations in Pipe Flow
𝑝 1 𝜌 + 𝛼 1 𝑉 𝑔 𝑧 1 − 𝑝 2 𝜌 + 𝛼 2 𝑉 𝑔 𝑧 2 = ℎ 𝑙 𝑇
This equation enables us to calculate the losses occurring in a section of the pipe. The values of 𝛼 are usually close to 1.
Each term in the equation has dimensions of 𝐿 2 𝑡 2 , so if we divide by 𝑔, it would have dimensions of length 𝐿.
𝑝 1 𝜌𝑔 + 𝛼 1 𝑉 𝑔 + 𝑧 1 − 𝑝 2 𝜌𝑔 + 𝛼 2 𝑉 𝑔 + 𝑧 2 = ℎ 𝑙 𝑇 𝑔 = 𝐻 𝑙 𝑇
𝑝 1 + 𝛼 1 𝜌 𝑉 𝑧 1 − 𝑝 2 + 𝛼 2 𝜌 𝑉 𝜌𝑔𝑧 2 =𝜌 ℎ 𝑙 𝑇 =𝐾 𝜌 𝑉 2 2
ME 322 THERMO-FLUIDS LAB-1
1/18/2019
ME 383 Fluid Mechanics

3. Major and Minor Losses in Pipes
9/24/2012
Major and Minor Losses in Pipes
Energy Considerations in Pipe Flow
𝑝 1 + 𝛼 1 𝜌 𝑉 𝑧 1 − 𝑝 2 + 𝛼 2 𝜌 𝑉 𝜌𝑔𝑧 2 =𝜌 ℎ 𝑙 𝑇 =𝐾 𝜌 𝑉 2 2
Major losses are due to friction between fluid and pipe, hence we can write the losses as,
ℎ 𝑙 =𝑓 𝐿 𝐷 𝑉 2 2
Where L and D are the pipe length and diameter, respectively.
Minor losses are due to fittings and or area changes
Inlets/Exits
Enlargements and Contractions
Pipe Bends
Valves and fittings
ℎ 𝑙 =𝐾 𝑉 =𝑓 𝐿 𝑒 𝐷 𝑉 2 2
We can define Le, equivalent length, for each type of fitting.
ME 322 THERMO-FLUIDS LAB-1
1/18/2019
ME 383 Fluid Mechanics

4. Major and Minor Losses in Pipes
9/24/2012
Major and Minor Losses in Pipes
Fittings: Area Change
ME 322 THERMO-FLUIDS LAB-1
1/18/2019
ME 383 Fluid Mechanics

5. Major and Minor Losses in Pipes
9/24/2012
Major and Minor Losses in Pipes
Fittings: Bends
ME 322 THERMO-FLUIDS LAB-1
1/18/2019
ME 383 Fluid Mechanics

6. Major and Minor Losses in Pipes
9/24/2012
Major and Minor Losses in Pipes
Fittings: Equivalent Length
The equivalent length
is calculated using the
flow velocity and Reynolds
number to get an estimate
for f using Moody chart
Using the estimated
value of K we can estimate
Le/D
ME 322 THERMO-FLUIDS LAB-1
1/18/2019
ME 383 Fluid Mechanics