MIXED FLOW PUMP DESIGN

[MONJON]

I am looking for some info. on mixed flow pump design.

I would like to predict input requirements as well as output performence before moving to the prototype stage.

I am working at designing a lower hp (15 hp) outboard motor jet design instead of traditional propeller.

Jet configuration is nothing more than a centrifugal screw pump with 3 blade impeller configuration instead of single blade.

Presently all outboard motor manufactures are purchasing their jet pumps from a supplier in California, which is not interested in manufacturing for lower horsepower engines.

Any help ould greatly be appreciated

Monjon

 

[fredb]

hello

see: Pump Handbook, McGraw-Hill, 2nd Edition, by Karassik et al, pages; 2.208, through 2.211

 

[MONJON]

Hello, fredb

Thank you for taking the time to answer.

I will do so.

Monjon

 

[Artisi]

Why not look at axial flow instead of mixed flow- - in one side and straight outr the other.
Ian

 

[MONJON]

The reason why this type of pump in used is that you can hide the impeller and volute behind the boat transom and introduce the inductor just bellow the boat bottom. This allows the boat to run in very shallow water 3-4 inches. I am trying to eliminate the propeller because it needs to be completely submerged in the water. The forward motion of the boat caused water to be taken from the front instead of the bottom.

 

[Artisi]

This has already be done very well with axial flow some 15 / 20 years ago by a guy named Hugh Nelson in Australia.
Sorry I can't give you any reference to it but at the time it was well documented - if you are going to search for it look for the name "Squid" - from memory this is what he named it.

 

[MONJON]

Artisi

Thanks for the reply.

Do you know if this was done on a outboard motor or was it inboard type like the axial jets used today on watercrafts and boats?

Monjon

 

[Artisi]

It was an inboard unit, and from memory the discharge nozzle was also arranged to be steerable and to give reverse thrust. I also think 1 unit was fitted to a large "rescue" boat in the USA and it won an award or set a new record of some sort.
Sorry I can't be more specific - but at the time I wasn't all that interested in it - just remember reading an article about it which would have come from a USA boating magazine.
Thinking back it was probably more like 30 years ago not the 15 / 20 I said originally.