How does energy extraction occur in a reaction turbine?

How does energy extraction occur in a reaction turbine?

• A. Channels the steam to collide with the turbine wall, which creates spin
• B. The steam momentum strikes the blade
• C. The turbine uses magnets to generate torque
• D. The steam is condensed before it leaves

Answer: (A)

The energy transfer in a reaction turbine comes from the steam’s energy being transferred to the rotor as the steam flows through and exerts forces on the blade surfaces. As steam expands, it is directed to move across the blade channels and collide with (or push against) the blade surfaces. That interaction changes the steam’s momentum and applies a reaction force to the blades, producing a turning moment that spins the rotor. In a reaction turbine, the blades are shaped to maximize this force transfer, so the steam’s pressure and velocity energy are converted into mechanical energy of rotation. Magnetic torque isn’t involved in a turbine, condensation before exit wastes usable energy, and simply letting steam leave without transferring momentum wouldn’t drive the rotor.

The energy transfer in a reaction turbine comes from the steam’s energy being transferred to the rotor as the steam flows through and exerts forces on the blade surfaces. As steam expands, it is directed to move across the blade channels and collide with (or push against) the blade surfaces. That interaction changes the steam’s momentum and applies a reaction force to the blades, producing a turning moment that spins the rotor. In a reaction turbine, the blades are shaped to maximize this force transfer, so the steam’s pressure and velocity energy are converted into mechanical energy of rotation.

Magnetic torque isn’t involved in a turbine, condensation before exit wastes usable energy, and simply letting steam leave without transferring momentum wouldn’t drive the rotor.