ME or MEng Master of Engineering Fluid Mechanics and Hydraulics 3

Question 1

A pump's specific speed is used to:

Accepted Answer

Classify pump type and predict performance

Answer

Specific speed N_s is a dimensionless parameter that classifies pumps (centrifugal, mixed-flow, axial) and guides selection for given flow and head conditions.

Question 2

Cavitation in pumps occurs when local fluid pressure drops below:

Accepted Answer

The vapor pressure of the fluid

Answer

Cavitation occurs when local static pressure falls below the fluid's vapor pressure, causing vapor bubble formation and collapse.

Question 3

The boundary layer on a flat plate transitions from laminar to turbulent at approximately which local Reynolds number?

Accepted Answer

Re_x = 5 × 10⁵

Answer

Boundary layer transition on a flat plate typically occurs at a local Reynolds number Re_x ≈ 5 × 10⁵ under low-disturbance conditions.

Question 4

Manning's equation in open-channel hydraulics relates flow velocity to:

Accepted Answer

Hydraulic radius, channel slope, and roughness coefficient

Answer

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.

Question 5

Stokes' Law for drag on a small sphere at very low Reynolds number gives drag force as:

Accepted Answer

F_D = 3πμVD

Answer

For creeping flow (Re << 1), Stokes' Law gives F_D = 3πμVD, where μ is dynamic viscosity, V is velocity, and D is sphere diameter.

ME or MEng Master of Engineering Practice Test

ME or MEng Master of Engineering Practice Test

ME or MEng Master of Engineering Fluid Mechanics and Hydraulics 3