impeller diameter calculation?
impeller diameter calculation?
(OP)
I am looking for a basic calculation for determining the optimum diameter for an impeller. For the sake of imformation:
Medium: water, low salt content
Maximum power: 12.5 Hp @ 3500 rpm
Maximum lift: 12"
Flow: as high as possible
The reason: I'm an aircraft mechanic who builds boats on the side. I have a request for a jet boat with minimal pressure differential. Basically, push a lot of water with minimal sediment disturbance in shallow areas.
Medium: water, low salt content
Maximum power: 12.5 Hp @ 3500 rpm
Maximum lift: 12"
Flow: as high as possible
The reason: I'm an aircraft mechanic who builds boats on the side. I have a request for a jet boat with minimal pressure differential. Basically, push a lot of water with minimal sediment disturbance in shallow areas.





RE: impeller diameter calculation?
Naresuan University
Phitsanulok
Thailand
RE: impeller diameter calculation?
On the discharge side, I don't see how a fast- moving jet of water is _not_ going to stir up sediment in shallow areas.
How about an airboat with a nontraditonal (e.g. quiet, e.g. extant) muffler?
Mike Halloran
Pembroke Pines, FL, USA
RE: impeller diameter calculation?
the airboat idea has the flaw that the prop will always make the same amount of noise for the thrust provided unless you invest in a true laminar flow prop (which are rediculously expensive).
RE: impeller diameter calculation?
I can't recall ever seeing one with a _muffler_.
;---
I suppose you could _try_ using two jet boat inlets back to back and a double bottom diffuser. I.e., instead of having the pump discharge through a nozzle, have it discharge through a diffuser. Expect a _lot_ less thrust than you get from the same pump working through a nozzle.
;---
There was an article in a recent WoodenBoat about an odd boat adapted for Florida's 'flats'. Sort of a tunnel hull with a nearly symmetrical tunnel, and virtually no notch in the transom. Sort of the same idea as above, without the double bottom. With a large slow turning prop, it might be satisfactory to your customer, and quie a bit easier to build.
;---
Or, you could go the complete opposite way, and use a high pressure jet boat pump discharging at high pressure into an array of thousands of very small nozzles. The wake would be like a rain squall hitting the surface.
Mike Halloran
Pembroke Pines, FL, USA
RE: impeller diameter calculation?