While doing experiments on a francis turbine, i noted that the discharge decreases when the load on shaft was increased, =>the speed was decreased. I was(in fact, I am) kind of confused about why it dropped, I did consult some text but didnt get any right reason. I thought that since the blade speed has decreased, the flow should have a lesser back pressure to tackle and should be more, but the reverse happens. Also, I thought since the speed is decreased and torque increased, flow must increase to account for the force, but again i was wrong(i eventually did some calculations and the increased torque problem was solved). Now then, here I stand with a doubtful explanation. I think, when the blade velocity decreases,the jet velocity is also decreased to maintain the inlet angle as close to blade angle as possible => ensuring shock less entry, this happens as the shock less entry will provide the minimum back pressure to the flow and thus flow drops a little bit. Is this reason good enough to explain the fall in discharge?? Again while doing experiment on a kaplan turbine, i noted that the blade's tip velocity is about 2 to 2.5 times the inlet jet velocity. How come that is possible? If it is, the machine should be a compressor! How can an incoming jet transfer momentum to a blade if the blade is already moving faster? I know that the velocity of blade changes with the radial distance of concerned section, but then the blade angle takes care of this and in now way, any part of blade can travel faster than the incoming jet, because that makes it a compressor, right??