Fluid Mechanics ..please help!?

Question

You are going to pump water from a farm pond to irrigate a field that is 65 feet higher than the surface of the pond. You have elected to use 4 inch schedule 40 pipe for this job and are going to pump 150 GPM in an effort to cover the 5 acre field in a timely manner. The length of the pipe from the pond to the Rain Bird is 1250 feet. There is one gate value that will normally be fully open and 12 standard 90o elbows in the system as well and 4 standard 45o elbows. Find the horsepower needed to power this system. Remember to calculate the entire HL. Is the flow in the pipe laminar or turbulent?

Answer 1

Edit

What is the operating pressure required at the connection to the Rain Bird ?

This pressure can be more significant than the equivalent length of the relatively few fittings. (There should also be a check valve at the pump discharge and possibly one on the suction. You will need a "clear well" incorporating a screen to keep debris out of the pump and probably an inline strainer at the Rain Bird which will add to the design pressure .)  Your friction loss will be 3ft /100ft of equivalent length. The flow is turbulent. The motor will be roughly 5 - 10 nominal horsepower depending on the above plus an assumed efficiency of the pump which will be 50-60% for this size.

Answer 2

All I'm sure is that the flow would be turbulent. Even that I'm not entirely sure of.

Answer 3

ask a plumber :)

Answer 4

Your data suggest that we should use 200 hp pump. Laminar flow is just theoretical flow. The most probable flow in this case would be Transistional Flow with Reynold No = roughly 2752 (may vary from 2500 to 3000 )

Dr. P.K.Tandon

Answer 5

good question let me solve this problem!