SPED Fluid Dynamics & Flow Analysis 2

Question 1

In a piping system, the Moody friction factor for fully turbulent flow in a rough pipe depends primarily on:

Accepted Answer

Relative roughness only

Answer

At fully turbulent (wholly rough) flow, the friction factor becomes independent of Reynolds number and depends only on relative roughness (ε/D).

Question 2

The hydraulic diameter for a rectangular duct with width W and height H is:

Accepted Answer

4WH / (2(W + H))

Answer

Hydraulic diameter Dh = 4A/P = 4WH / (2(W+H)), used to apply circular-pipe correlations to non-circular cross sections.

Question 3

Which phenomenon causes pressure oscillations when a valve is rapidly closed in a liquid piping system?

Accepted Answer

Water hammer

Answer

Water hammer (hydraulic shock) occurs when rapid valve closure converts kinetic energy of flowing liquid into pressure waves that travel through the system.

Question 4

For two-phase gas-liquid flow, the Lockhart-Martinelli parameter X is used to characterize:

Accepted Answer

The ratio of frictional pressure drops of liquid and gas phases flowing alone

Answer

The Lockhart-Martinelli parameter X² is the ratio of frictional pressure drop of the liquid phase alone to that of the gas phase alone.

Question 5

The continuity equation for steady incompressible flow through a converging nozzle states that:

Accepted Answer

The product of area and velocity is constant

Answer

Continuity for incompressible flow requires A₁V₁ = A₂V₂, so as area decreases, velocity must increase proportionally.

(SPED) Society of Piping Engineers and Designers Certification Practice Test

(SPED) Society of Piping Engineers and Designers Certification Practice Test

SPED Fluid Dynamics & Flow Analysis 2