Volumetric Flowrate of a jet boat

[Scottintexas]

I just thought since a flyboard relies on that pressure they might have more knowledge of the actual output,

 

[Speedling]

In simle math terms. Wouldnt the diameter of the impeller, the blade pitch and rpms define an approximate volume/displacement?

Not until you take into account that it is reduced to a different diameter nozzle thus increasing the pressure and velocity of the water.

 

[tdonoughue]

Actually, it would be practically the same volume/displacement. The same amount of water is moved regardless of the nozzle diameter (after a certain insignificant loss for additional friction). Decreased diameter does increase pressure and velocity, but the volume remains the same.

That said, the calculation of the impeller effect would be non-trivial. The diameter of the impeller may not be constant (curved at tip) and the blade pitch may not be constant (increasing/decreasing with rotation or radius).

Thus we mash the throttle and hang on.

 

[Speedling]

Actually, it would be practically the same volume/displacement. The same amount of water is moved regardless of the nozzle diameter (after a certain insignificant loss for additional friction). Decreased diameter does increase pressure and velocity, but the volume remains the same.

That said, the calculation of the impeller effect would be non-trivial. The diameter of the impeller may not be constant (curved at tip) and the blade pitch may not be constant (increasing/decreasing with rotation or radius).

Thus we mash the throttle and hang on.

You're right that the volume at impeller is the same at the nozzle! Don't know what i was thinking there. I do know that like you said, it's nearly impossible to calculate at the impeller!

Need a psi gauge at the nozzle to read pressure, then multiply (?) by the 82mm or whatever it is, to get a volume.

 

[RForester]

There is a way to tell. It involves measuring how far it takes for the top of the stream to fall to the bottom of the orfice. I have a book at work that has the equation. It's pretty simply math, but we need the measurement. And the diameter of the jet. Of course I need my book at work and since it's Saturday... Ha!

Getting the measurement would involve somehow getting a water supply to the jets while the boat is out of water.

 

[RForester]

Enough volume to be dangerous to rectal and vaginal cavaties.

My daughters get the biggest kick out of that sticker!