Frictional Losses in Straight Pipes

What does “head” loss mean?

Loss in capability to increase height of fluid

What is the cause of pipe friction, head loss?

due to fluid friction (viscosity)

What are the consequences of pipe friciton?

increased pumping power, reduced fluid flow, reduced available fluid power

Are losses from straight pipe major or minor?

major

What’s this equation for?

MAJOR head loss in a circular pipe (laminar flow)

What’s this equation for?

MAJOR head loss in circular pipe

What are the axis label of the MOODY Diagram?

Re, Relative Roughness, friction factor

What does the piping schematic for this lab look like?

What does the decreasing height in the static pressure tubes mean?

Decreasing height = decreasing static pressure

What are the components of the experimental apparatus?

• 55 gal tank

• 1.85 HP swimming pool pump

• PVC pipe

• Hoffer turbine flowmeter

• bourdon pressure gage

• galvanized steel pipe test section

• flexible Tygon tubing for static pressure measurements

Total head loss

the sum of major losses, h₁, caused by friciton in the piping and the minor losses h_1m, caused by entrance effects and non-straight piping elements such as, fittings, valves, etc.

What assumption do we make in this experiment?

we neglect the entrance losses

What are the variables in this equation?

What reynolds number is considered to be laminar

Re < 2300

What is this equation for?

The velocity profile of a fully-developed laminar flow

For turbulent flows pressure drop is a function of what variables?

What are the objectives of this experiment

Measure the pressure drop in a known length of straight pipe, determine the value for the friction factor experimentally, and compare your measured f values against the theoretical (laminar) and empirical (turbulent) f values for your test values of Re and e/D.