Case 22: Bespoke Fluid - Inclined Pipe Friction Loss

Reference: 2500 Solved Problems in Fluid Mechanics and Hydraulics, 1989, McGraw-Hill, Jack B. Evett, Ph. D., Cheng Liu, M.S., Page 190, Example problem 8.125

Pipe Flow Expert Files:

Case_22_Bespoke_Fluid_Inclined_Pipe_Friction_Loss_Part_1.pfe Case_22_Bespoke_Fluid_Inclined_Pipe_Friction_Loss_Part_2.pfe

Problem Description:

An inclined pipe connects two points at which the fluid pressure is 20 psi and 30 psi.

The elevation of the 20 psi point is 25 ft above the elevation of the 30 psi pressure.

Assume flow direction from the upper point to the lower point.

The length, diameter and internal roughness of the pipe are unspecified.

1. If the fluid density is 30 lbs/ft³ calculate the friction loss in the pipe. Check the direction of the flow.

2. If the fluid density is 100 lbs/ft³ calculate the friction loss in the pipe. Check the direction of the flow.

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Fluid Data: Fluid density as stated above.

Result Comparison:

Fluid density	Data Item	Published data	Flow Direction	Pipe Flow Expert	Pipe Flow Expert
30 lbs/ft³	Pipe Friction head (ft)	-23.0	From lower point to upper point	-23.0	Correctly reversed flow direction of the pipes

Fluid density	Data Item	Published data	Flow Direction	Pipe Flow Expert	Pipe Flow Expert
100 lbs/ft³	Pipe Friction head (ft)	10.6	From upper point to lower point	10.6	Confirmed flow direction of the pipes

Commentary:

The published data and the calculated results compare well.

The length, diameter and internal roughness of the pipe have no effect on the Pipe Friction Head in this example.

The pipe friction head is dependant on the pressure difference, the difference in elevations and the density of the fluid in the pipe.

The flow rate in a particular pipe must produce a frictional loss equal to the pressure difference between the two points, therefore if the pipe characteristics are changed the flow rate in the pipe will change.

Several different pipe diameters, pipe length and internal roughness values were used in the Pipe Flow Expert calculations to ensure that these factors did not effect the calculations.

In each case Pipe Flow Expert solved the individual pipe calculation by finding and using a different flow rate which would produce the identical Pipe Friction Head.