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Critical (throat) pressure in a De Laval nozzle: superheated steam 10 bar → 0.1 bar Given: Superheated steam expands from 10 bar to 0.1 bar in a De Laval nozzle. Find: Pressure at the minimum area (throat) at choked condition using the standard critical ratio for superheated steam. Choose the correct option.

Difficulty: Easy

3.3 bar
5.46 bar
8.2 bar
9.9 bar

Correct Answer: 5.46 bar

Explanation:

Given
Upstream pressure p₁ = 10 bar (superheated)Critical pressure ratio for superheated steam ≈ 0.546

Step-by-step
p_throat = 0.546 × p₁= 0.546 × 10 bar= 5.46 bar

Common pitfall
Using the wet-steam critical ratio (≈ 0.577) would give 5.77 bar, which is not applicable here since the prompt specifies superheated steam.

Final Answer
5.46 bar

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