Difficulty: Easy
Correct Answer: No, it measures the shortfall in tangential (whirl) velocity at impeller exit due to finite blade effects
Explanation:
Introduction / Context:
“Slip factor” is a core performance parameter for centrifugal compressors. It is often misunderstood as a mechanical leakage measure, whereas it actually relates to aerodynamics at the impeller exit and the head predicted by Euler’s equation.
Given Data / Assumptions:
Concept / Approach:
Slip factor σ is typically defined as Vw2(actual)/Vw2(ideal) or as Vw2(actual)/u2 depending on convention. Because real blades cannot turn the flow perfectly, the actual tangential (whirl) component Vw2 is less than the ideal value, reducing the ideal Euler head and the pressure rise achievable per stage.
Step-by-Step Solution:
Verification / Alternative check:
Empirical correlations (Stodola, Wiesner) estimate σ from geometry and blade count, validating the aerodynamic nature of the parameter.
Why Other Options Are Wrong:
Options suggesting storage or bearing leakage misinterpret an aerodynamic efficiency parameter as a mechanical loss metric.
Common Pitfalls:
Equating “slip” with “leak”; assuming σ reflects casing clearances rather than exit flow deviation.
Final Answer:
No, it measures the shortfall in tangential (whirl) velocity at impeller exit due to finite blade effects
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