fluid mechanics i me362 - arab academy for science

Fluid Mechanics I – ME362*

Arab Academy for Science, Technology

and Maritime Transportation

Dr. Ahmed Khalifa Mehanna

Associate Professor

a.khalifa@aast.edu

ahmed_marines@yahoo.com

Room No: 223

Course Assistant Lecturer:

Eng. Omar Mostafa

Lecture 11:

Flow through Pipes – Part II

Fluid Mechanics I – ME362*

Recall the Typical pipe system components

Minor Loss in Pipe Flow

Total Head Losses

Example

Lecture Outline

Typical pipe system components

In addition to frictional losses, thereare minor losses due to

Entrances or exits

Expansions or contractions

Bends, elbows, tees, and otherfittings

Valves

Losses generally determined byexperiment and then correlated withpipe flow characteristics.

Loss coefficients are generally givenas the ratio of head loss to velocityhead.

Abrupt inlet, K ~ 0.5

g

VKh

g

Vh mmK

2or )

2(

22

Minor losses - Entrance Loss in Pipe

• A piping system may have many

minor losses which are all

correlated to V2/2g

• Sum them up to a total system

loss for pipes of the same

diameter

Where,

m

m

m

mfL KD

Lf

g

Vhhh

2

2

m lossheadTotalLh

m loss head Frictionalfh

mhm fitting forlossheadMinor

fitting fortcoefficienlossheadMinormK

Total Head Losses

Minor Head Loss for Fitting

Lists of loss coefficients K for four types of valve,

three angles of elbow fitting, and two tee connections

Given: Liquid in pipe has = 8 kN/m3.

Acceleration = 0. D = 1 cm, µ = 3x10-3 N.m/s2.

Find: Is fluid stationary, moving up, or moving

down? What is the mean velocity?

Solution: Energy eq. from z = 0 to z = 10 m

smV

*x*

).*(.V

μL

γDhV

γD

μLVh

mh

h

h

zp

g

Vhz

p

g

V

-

L

L

L

L

L

L

/04.1

1010332

0108000251

32

32

upward) (moving25.1

108

90

108000

000,110

8000

000,200

22

3

2

2

2

22

2

21

1

2

1

1

2

Example

Example

Example

Example