Mass discharge in a convergent–divergent steam nozzle after the throat Statement completion: In an ideally operating C–D nozzle with choked flow at the throat, the discharge (mass flow rate) of steam __________ in the divergent portion after the throat. Choose the correct completion.
Mechanical Engineering
Steam Nozzles and Turbines
Difficulty: Easy
Choose an option
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AIncreases continuously
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BDecreases continuously
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CRemains constant
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DBecomes sonic and then subsonic
Answer
Correct Answer: Remains constant
Explanation
Given/Definitions
- Steady 1-D nozzle, choked at throat (Mach = 1).
Concept/Approach
- For steady flow, mass flow rate ṁ = ρ A V is constant along the nozzle in the absence of leakage or extraction.
- After choking, changes in A, ρ, and V adjust so that ṁ stays the same; thus the discharge remains constant along the C–D nozzle.
Common pitfalls
- Velocity increases in the divergent section for supersonic steam, but mass flow rate does not change.
Final AnswerRemains constant