EULER’S EQUATION FOR AN IMPELLER E017
Mr. Euler stated that “the torque required to drive an impeller is equal to the change of moment of momentum of the fluid passing through the impeller”.
A perfect impeller has a great number of vanes of infinitesimal thickness with the particles of the liquid flowing exactly parallel to the vanes surface without causing any friction.
If you had such conditions, Euler’s equation would predict the head the impeller would produce and the torque required to produce it.
Since we’re not in a perfect world, pump companies perform actual pumping tests and record the results on a pump curve, so that you can see the correlation between the pump’s head and capacity.