Function of a steam nozzle in turbines and jets:\nWhat principal energy conversion takes place in a steam nozzle?

Introduction / Context:
Steam nozzles are critical in turbines, ejectors, and other devices where a high-velocity jet is needed. They convert the thermodynamic availability in high-pressure, high-temperature steam into directed kinetic energy for doing mechanical work on turbine blades or entraining secondary flows.

Given Data / Assumptions:

• Steam expands through a shaped passage (nozzle).
• Negligible shaft work; energy conversion is primarily flow work and enthalpy drop to kinetic energy rise.
• Adiabatic approximation is often used.

Concept / Approach:
Across a nozzle, the stagnation enthalpy decreases as static kinetic energy increases. The first law for steady flow reduces to h1 + V1^2/2 ≈ h2 + V2^2/2 (neglecting heat, shaft work, elevation). Thus, the enthalpy (thermal) content is converted to kinetic energy, producing a high-speed jet that can drive impulse stages or create suction in ejectors.

Step-by-Step Solution:

Verification / Alternative check:
Measured nozzle exit velocities correlate with enthalpy drops from steam tables, validating the energy conversion mechanism.

Why Other Options Are Wrong:

• Kinetic → heat or potential → heat: Opposite of nozzle intent.
• Heat → potential energy: Potential energy changes are negligible compared to kinetic rise.

Common Pitfalls:
Ignoring losses; real nozzles have efficiency less than 100%, so actual velocity is less than the ideal value derived from the enthalpy drop.

Final Answer:
heat energy of steam into kinetic energy