Difficulty: Easy
Correct Answer: Pitot tube
Explanation:
Introduction / Context:
Hydraulic engineers employ various instruments to quantify flow. While Venturimeters and orifice meters infer discharge from pressure differences across constrictions, a Pitot tube directly senses local velocity through stagnation pressure.
Given Data / Assumptions:
Concept / Approach:
The Pitot tube measures stagnation and static pressures, whose difference relates to the dynamic pressure. Using Bernoulli’s relation, the local velocity is obtained via V = C * sqrt(2 * (p_t − p_s) / rho). In contrast, Venturimeter and orifice meter provide section discharge Q; velocity is then Q/A and not strictly a point value.
Step-by-Step Solution:
Verification / Alternative check:
Compare with a calibrated current meter (open channels) or with PIV/LDV in labs; results align within instrument uncertainty when properly used.
Why Other Options Are Wrong:
Venturimeter and orifice meter measure discharge over a section, not point velocity. “Current meter only” ignores that a Pitot tube is the canonical point-velocity device. “None of these” is incorrect.
Common Pitfalls:
Not correcting for velocity profile when converting point velocity to average velocity, and misalignment causing under-reading.
Final Answer:
Pitot tube
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