Question 564Steam Plants - Assistant Engineer

The correct answer is D) two or more stages of velocity compounding. A pressure-velocity compounded impulse turbine consists of two or more stages of velocity compounding, where the steam is expanded through a series of nozzles and blades. This allows the steam to undergo both velocity compounding and pressure compounding, making it more efficient than a simple impulse turbine. The other options are incorrect because: A) a pressure-velocity compounded turbine does not have diaphragms, B) it involves both velocity compounding and pressure compounding, not just velocity compounding with reaction pressure compounding, and C) it has multiple stages of nozzles, not just a single row with no pressure drop.