Calculating Pump Power

[TBarnett12]

Hey so Ive been asked by my work to design a display model that needs to be able to flow 0.05-0.15 cms. They have told me to use an impeller assembly from a jet ski for the pump and want me to size an electric motor that will be capable of delivering the power required to pump the water. The only things that I know are: the maximum thrust generated from the impeller (lbf), the rpm of the shaft to generate the maximum thrust, the horsepower of the motor used to generate the maximum thrust, the angle of the impeller blade, and the required flow rate for the model. Does anyone have any suggestions on how to calculate the required horsepower needed to power one impeller and have it generate the flows I need? Thanks in advance for any advice.
Taylor

 

[Kuhuh]

I think this would be right if you know the frequency of the motor you can check to see the synchronous speed to make sure with the efficiencies but this should give you a start

http://files.engineering.com/getfile.aspx?folder=0a6d94f0-b08e-4504-86fa-e0d6d2bfa821&file=pump.pdf

 

[Artisi]

That is 0.05 - 0.15 Cubic metres / second ?

Power required is simply - flow x head produced / pump efficiency and has nothing to do with speed, blade angles or thrust.

Your posting is also very confusing in that you say you already have this information:
"The only things that I know are: the maximum thrust generated from the impeller (lbf), the rpm of the shaft to generate the maximum thrust, the horsepower of the motor used to generate the maximum thrust, the angle of the impeller blade, and the required flow rate for the model."



It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[TBarnett12]

Artisi, the first thing that I did was calculate power the way you explained above. My boss told me that he also wanted me to calculate the power based off of the impeller speed and blade angle. Im not the greatest with pumps so I just assumed that there was another way to calculate power that my school didnt teach civils. Sorry if my post seems confusing, Im pretty confused myself.

 

[Artisi]

In that case ask him how you should go about it.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[Kuhuh]

The way I posted previously accounts for impeller speed!
Here is a link that gets more involved with impeller angle and length of blades to develop an equation for thrust. Just use density of water instead of air.

http://www-mdp.eng.cam.ac.uk/web/library/enginfo/aerothermal_dvd_only/aero/propeller/prop1.html

 

[BigInch]

Why do all that to size the motor??? I didn't see where your boss told you to design the pump too.

Let your acquaintances be many, but your advisors one in a thousand’ ... Book of Ecclesiasticus