FRICTIONAL HEAD LOSSES IN PIPES

TALKING HEADSCLAUDE COLLIER KELSEY HENDERSON GARRET OZBOLT MICHAEL SCOTT-PIESCO

1

PRESSURE DROP IN PIPES:INTRODUCTION• Necessity of Fluid Transport• Fluids move from high to low energy state• Incur energy losses• Pump Sizing• Piping Arrangement

2

PRESSURE DROP IN PIPES:INTRODUCTION• Energy Equation for Fluids:

3

FRICTION IN PIPES• “Skin Friction”

or ….

4

𝑃1

𝛾 +𝛼1

𝒗 122𝑔 +𝑧1+h𝑝=

𝑃2

𝛾 +𝛼2

𝒗222𝑔+𝑧2+h𝑇+h𝑓 +h𝑐

FANNING FRICTION FACTOR

5

• Definition: “The drag force per wetted surface unit area (shear stress at the surface) divided by the product of density times the velocity head.”

Head Loss: Operative:

FLOW REGIMES

6

• Reynold’s Number

PIPE ROUGHNESS

7

MOODY DIAGRAM

8

ORIFICE METERS

9

• Plate with bore

• Pressure taps on both sides

• Measures Flow

OBJECTIVES• Qualitatively determine relationship between friction

losses, Reynolds number, and relative roughness• Estimate orifice meter coefficient• Estimate absolute roughness of PVC pipe

10

SAFETY

11

EQUIPMENT

12

ROTAMETERS

13

• Height of float is directly proportional to fluid flow rate. This one measures in percent flow.

PROCEDURE• Produce rotameter calibration curve• Direct flow using valves on assembly• Connect DP cell to pressure taps on desired pipe or

component• Set flow to 100% flow on rotameter, and begin decreasing

until 0%, recording DP meter output along the way• Run procedure for 1" pipe, 3/4" pipe, and orifice meter

14

CALCULATING FANNING FRICTION FACTOR AND REYNOLDS NUMBER

15

COMPARISON OF REYNOLDS NUMBER AND FANNING FRICTION FACTOR

16

0 10000 20000 30000 40000 50000 60000 70000 800000

0.002

0.004

0.006

0.008

0.01

0.012

1" Schedule 80 PVC pipe3/4" Schedule 80 PVC pipe

Reynolds number

Fann

ing

frict

ion

fact

or

COMPARISON OF REYNOLDS NUMBER AND FANNING FRICTION FACTOR OF DIFFERENT PRESSURE TAPS

17

0 10000 20000 30000 40000 50000 60000 700000

0.002

0.004

0.006

0.008

0.01

0.012

Taps 1&5Taps 1&4Taps 2&4Taps 2&5

Reynolds number

Fann

ing

frict

ion

fact

or

CALCULATE ABSOLUTE ROUGHNESS COEFFICIENT:SHACHAM EQUATION

18

ε = 0.0082Accepted value: 0.0015

FINDING ORIFICE METER COEFFICIENT:PLOT VOLUMETRIC FLOWRATE AGAINST SQUARE ROOT OF PRESSURE

19

0 100 200 300 400 500 600 7000

100

200

300

400

500

600

700

800

900

f(x) = 1.20717627462909 x − 26.3465218894154R² = 0.99972714439584

P1/2 (cm1/2 H2O)

Volu

met

ric F

low

Rat

e (c

m3/

s)

FINDING ORIFICE METER COEFFICIENT:USE SLOPE OF GRAPH TO SOLVE FOR COEFFICIENT

20

Co = 0.754Accepted value: 0.6-0.65

IN CONCLUSIONFanning friction factor and Reynolds Number

Showed the expected trends quantitativelyError at lower flow rates due to differential pressure readings

9/23/15

Convective Heat Transfer Experiment 21

25000 30000 35000 40000 45000 50000 55000 600000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

Taps 1&5Taps 1&4Taps 2&4Taps 2&5

Reynolds number

Fann

ing

frict

ion

fact

or

IN CONCLUSIONRelative roughness of pipe

Produced result 10X larger than expected, 0.014mm as opposed to accepted value of 0.0015mm, error most likely from differential pressure meter readings being off

22

IN CONCLUSIONOrifice meter coefficient

Value of 0.75 is slightly high, however reasonable given the accepted value is 0.6-0.65

23

RECOMMENDATIONS

24

QUESTIONS?Thank you for your attention

25