Surge Analysis – Water Hammer

These equations are primarily used for calculating pressure drops and flow rates. However, a modified Reynolds number must be used. When calculating flow rate or internal pipe diameter, a modified Reynolds number must be calculated first using the up or down stream calculations to run these calculations. No internal roughness considered.

Friction factor is solved using Newton-Raphson method.
PTLB Hydraulics Liquid 2.7 Intro_2.png

𝑓 − Friction Factor

D – Inside Pipe Diameter[in]

𝜀 − Pipe Roughness[in]

The momentum continuity equations
PTLB Hydraulics Liquid 2.8 Intro.png

Infinite difference form could be seen:
PTLB Hydraulics Liquid 2.8 Intro_2.png

The equations simplify to
PTLB Hydraulics Liquid 2.8 Intro_3.png

These equations combined linearly using an unknown multiplier 𝛌
PTLB Hydraulics Liquid 2.8 Intro_4.png
Further

PTLB Hydraulics Liquid 2.8 Intro_5.png

Equation E becomes ordinary differential equation

PTLB Hydraulics Liquid 2.8 Intro_6.png
The solution of this equation yields the two-particular value of

By substituting the values of in the equation, the particular manner in which x and t are related is

Input Parameters

To create a new case, click the “Add Case” button
Select the Unknown and desired Flow Equation.
Enter Case Name, Location, Date and any necessary notes.
Fill out all required fields.
Make sure the values you are inputting are in the correct units.
Click the CALCULATE button.

Flowing Temperature(°F)
Liquid Specific Gravity
Upstream Pressure(psig)
Flow Rate (MCFD)
Internal Pipe Diameter(in)
Kinematic Viscosity
Length of Pipeline(mi)
Upstream Elevation(ft)
Downstream Elevation(ft)

PLTB Hydraulics-Liquid 2.8_Input Revision_07232020.png

Outputs/Reports

View the results.
If an input parameter needs to be edited be sure to hit the CALCULATE button after the change.
To SAVE, fill out all required case details then click the SAVE button.
To rename an existing file, click the SAVE As button. Provide all case info then click SAVE.
To generate a REPORT, click the REPORT button.
The user may export the Case/Report by clicking the Export to Excel/PowerPoint icon.
To delete a case, click the DELETE icon near the top of the widget.

Flow Rate(ft/sec.)
Pressure Drop [psi/mi]
Calculated modified Reynolds Number
Upstream Pressure(psi)
Downstream Pressure(psi)
Internal Pipe Diameter(in)
Erosional Velocity (ft/sec.)
Sonic Velocity (ft/sec.)

PLTB Hydraulics-Liquid 2.8_Output Revision_07232020.png