Discharge from end of pipe

[Zoobie]

If I have an open-ended pipe, oriented horizontally, discharging a fluid to atmosphere with known velocity can I estimate the arc that the fluid will travel (x distance for a given y) by using the basic physics formulas for projectile motion? If not, what would work? I am only looking for a reasonable estimate. While not the actual application, the best mental picture would be holding a garden hose and wanting to know how if I can hit my wife's petunias without getting up off the lawn chair.

 

[stanier]

Yes you can. Any reasonable fluids mechanics textbook will give you the formulae. The arc will be parabolic from memory.

Bssic mechanics (projectiles) will tell you if the velocity of an object fired horizontally is subjected to gravity then the distance travelled can be determined. The inital horizontal velocity is a function of the flow rate.

 

[Zoobie]

Thanks, Stanier I recall doing something like this in an assignment when I was back in school but that was a few moons ago. My problem stemmed from "any reasonable fluids mechanics textbook". Its been years but I am still bitter at my fluids prof. He was some young MIT hotshot who thought that for his first try at teaching that he would change the textbook that had been used at the school for years. The book he chose was small, very very expensive, and it has the value of toilet paper (barely)...not one practical example in my view.

Could you recommend a good fluids book that would be a good addition to my library. Crane is great for pipe flow issues but I wouldn't mind having a more comprehensive reference.

 

[TBP]

If you can come at it from another way, and just need to estimate it, there's a table in the little book "Handyman In Your Pocket" by Young & Glover (the same guys that do the "Pocket Ref") that shows flows from horizontal, open ended pipe from 1" through 12". You need to be able to measure how far out from the end of the pipe that the water stream has dropped 4". With that length, and the diameter of the pipe, you can read the flow off the table. If you know the GPM and pipe diameter, you could back your way out to the length table. I don't know if that helps you, but there it is, for what it's worth.

 

[jte]

Not strictly a fluid dynamics reference, but the Mechanical Engineering Reference Manual by Michael Lindeburg which is actually a study guide for the ME PE test is a useful general reference. I have the 8th edition. The fluid dynamics section includes a part about determining the horizontal and vertical dimensions of a stream of fluid flowing from a tank nozzle. I figure this could be applied to your pipe flow situation easily enough.

jt