College of EngineeringFLUIDS LABORATORY

Measurement of Velocity Profile andHead Loss/Friction Factor in Pipe Flow

Purpose

Re

To measure flow rate, friction factor, and velocity profile in pipe flows with smooth and rough walls and specified turbulent-

flow Reynolds number ( ) and compare the results with benchmark data , including uncertainty analysis for the friction

factor and velocity profile.

Test Design

Air is blown into a large reservoir located at the upstream end of the pipe system. Pressure built up in the reservoir forces air to

flow downstream through any of the three straight experimental pipes. At the downstream end of the system, the air is

directed downward and back through any of the three other pipes fitted with venturi meters.

Measurement Systems

Results

Block diagram of the experimental determination of the friction factor

Data Analysis

�

�

�

Obtain and plot the velocity profile and

compare with benchmark data

Determine the friction factor using the

pressure measurements and the Darcy-

Weisbach equation and compare with

benchmark data

Estimate experimental uncertainties

Comparison between reference data for the velocity profile and friction

factor and the experimental resultsBlock diagram of the velocity measurement

Measurement of Velocity Profile andHead Loss/Friction Factor in Pipe FlowMeasurement of Velocity Profile and

Head Loss/Friction Factor in Pipe Flow

Air-flow pipe system

Pressuretaps

Motorcontroller

Floor

6’-6

”

Re

se

rvo

ir

2.0” smooth

0.5” smooth

2.0” rough

Reliefvalves

Blower

D = 2.0”D = 1.0”

D = 0.5”

tt

t

36’

Venturi meter gate valvesThermometer

1 2 3 4

Valve manifold

Simplemanometer

Pitot tubehousings

Valves

Differentialmanometer

Venturi meters

r/R

-1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00

u/U

max

0.0

0.2

0.4

0.6

0.8

1.0

Reference data (Schlichting, 1968) - Re = 1.1e5

Smooth Pipe (Re=1.56e5)

Rough Pipe (Re=1.49e5)

EXPERIMENTALRESULT

w

w

T

TB T, P

STAGNATIONPRESSURE

STATICPRESSURE

EXPERIMENTAL ERROR SOURCES

INDIVIDUALMEASUREMENT

SYSTEMS

MEASUREMENTOF INDIVIDUAL

VARIABLES

DATA REDUCTIONEQUATIONS

z

B , P

SM

B , Pu u

u

= F(T )�

�

u = F( , , z , z )� �

2( ) g�

�

½

=

TEMPERATUREWATER

TEMPERATUREAIR

w

a stag

a

T

TB T, Pa

z

w

w

w

SMstag

zSM

stag

z

B , P

SMstat

zSM

stat

zSM

stat

= F(T )a

aa SM

stagSM

stat

zSM

stag

- zSM

stat

w

a

EXPERIMENTALRESULTS

EXPERIMENTAL ERROR SOURCES

INDIVIDUALMEASUREMENT

SYSTEMS

MEASUREMENTOF INDIVIDUAL

VARIABLES

DATA REDUCTIONEQUATIONS

TEMPERATUREWATER

TEMPERATUREAIR

fB , P

VENTURIPRESSURE

PIPEPRESSURE

f = F( , , z , Q =� � )a

a

wg D�

8LQ

�

�

Q = F( z )�

w

w

T

TBT

, P

z

zB , P

f f

SM

SMww

DM

SM

2

2

5

aT

TBT

, Paa

zSM

z

zB , P

DM

DMz

DM

= F(T )�

�

( )

w

= F(T )a

zSM

i

- zSM

j

w

a

0.002

0.001

0.0008

0.0006

0.0004

Smooth Pipe

Rough Pipe

104

105

106

Reynolds Number Re =VD

�

0.015

0.016

0.017

0.018

0.019

0.020

0.021

0.022

0.023

0.024

0.025

Frictio

nF

acto

rf

=h

f

(L/D

)V2 /(

2g

)

Re

lative

Ro

ug

hn

ess,

/D�

Uncertainty band for

+5% in �Smooth Pipe

Rough Pipe

Re 1.5 x 105

Reference Data(Moody Diagram)