Calculating the efficiency of a water turbine

bmwm3

Hi,


I am having trouble calculating the efficiency of a water turbine. The turbine in question closely represents a cross flow water turbine.

I have tested the power rating experimentally using a small DC motor and have found the output to be 400 mW.

I now need to find the power rating theoretically, I know there is a force of 155 N acting upon the blade of the turbine. The distance between the centre of the shaft and the edge of the blade is 25mm.

I know the velocity of water before hitting the turbine to be 20 m/s.

Many thanks in advance for any help you can give me!