Exit velocity is the nozzle exit speed. The water exists the nozzle and hits the turbine. With that said, turbine efficiency is not strictly based on resistanc

Exit velocity is the nozzle exit speed. The water exists the nozzle and hits the turbine. With that said, turbine efficiency is not strictly based on resistance. Rather it is about extraction of energy. In a few designs it looks like resistance, others it is about redirection: https://www.energy.gov/eere/water/types-hydropower-turbines https://www.energy.gov/eere/water/types-hydropower-turbines