Hi, I have never found a satisfactory explanation for why the Bernoulli equation is not valid when the streamline passes through a turbine, pump or another work transferring device. I have read many books that simply state this limitation without providing a convincing reason. Bernoulli equation can be derived by integrating the Euler's equation for a steady, inviscid, incompressible flow along a streamline. So, it should be valid for steady, inviscid, incompressible flow regardless of whether a work-transferring device is present or not, shouldn't it? (because the Euler equation is valid at all points for such flows, and the Bernoulli equation is just the intergrated version of it) Can anyone provide me a detailed explanation for this limitation of the Bernoulli's theorem?