Example:
using design data
Given:
Rn = V = 3.48 ft per/sec
D = .53 ft
Y = .0000128 ft/sec
V = Q = 3.48 x .53 = 1.8444
= 144093.75
A
.0000128
.0000128
= 144094 or 1.44 x 10 to the 5th
PART E TYPES OF FLOW
Types of flow. How do you interpret the Reynolds number once you
have calculated it?
Laminar flow. Laminar flow is undesirable in multi-product pipeline
operations because it has a telescoping effect on the product and
causes an increase in the spread of the interface.
Turbulent flow. Turbulent flow on the other hand will hold the spread of
the interface to a minimum.
In laminar flow the Reynolds number is 2,000 or below, in turbulent flow the
Reynolds number is 4,000 and above. The numbers between 2,000 and 4,000 are
considered transition flow.
Friction Factor (resistance to flow in pipeline operations). After
calculating the Reynolds number and changing to scientific notation, we can
obtain a friction factor using Figure 1-2. Horizontally across the bottom
are numbers in scientific notation, to the right and vertically is pipe
diameters, to the left of the graph and vertically are the friction factors
starting at .010 and ending with .032. Using our calculation 1.44 X 10 to
the 5th, locate this on the bottom horizontal line. The pipe diameter is
6.415 inches; move up the chart until the line intersects the pipe diameter
curve and move to the left and read .0188 for the friction factor.
Darcy Weisbach Equation
The Darcy Weisbach equation provides an accurate method of calculating
friction head loss in a pipeline. This equation should be used when a high
degree of accuracy is required. An example would be the construction of a
permanent pipeline system. The Darcy Weisbach equation states that:
Where:
Hf = friction head loss, in ft
f = dimensionless friction factor
V = velocity, in ft/sec
g = acceleration due to gravity (32.2 ft/sec)
d = inside diameter of the pipe, in ft
L = length of pipe, in ft
Hf = fxLxV
2g x d
12-12
QM 5099
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