Fluid Mechanics and Hydraulics Flashcards
6 cards from real ME or MEng Master of Engineering practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Fluid Mechanics and Hydraulics flashcards as text
A pump's specific speed is used to:
Answer: Classify pump type and predict performance
Specific speed N_s is a dimensionless parameter that classifies pumps (centrifugal, mixed-flow, axial) and guides selection for given flow and head conditions.
Cavitation in pumps occurs when local fluid pressure drops below:
Answer: The vapor pressure of the fluid
Cavitation occurs when local static pressure falls below the fluid's vapor pressure, causing vapor bubble formation and collapse.
The boundary layer on a flat plate transitions from laminar to turbulent at approximately which local Reynolds number?
Answer: Re_x = 5 × 10⁵
Boundary layer transition on a flat plate typically occurs at a local Reynolds number Re_x ≈ 5 × 10⁵ under low-disturbance conditions.
Manning's equation in open-channel hydraulics relates flow velocity to:
Answer: Hydraulic radius, channel slope, and roughness coefficient
Manning's V = (1/n)R_h^(2/3)S^(1/2) links mean velocity to hydraulic radius R_h, channel slope S, and Manning's roughness coefficient n.
Stokes' Law for drag on a small sphere at very low Reynolds number gives drag force as:
Answer: F_D = 3πμVD
For creeping flow (Re << 1), Stokes' Law gives F_D = 3πμVD, where μ is dynamic viscosity, V is velocity, and D is sphere diameter.
The energy grade line (EGL) in pipe flow lies above the hydraulic grade line (HGL) by a distance equal to:
Answer: V²/2g (velocity head)
EGL = HGL + V²/2g; the EGL exceeds the HGL by the velocity head, and both slope downward in the direction of flow due to friction losses.