NAPT Fluid Mechanics and Hydraulics 2

Question 1

Laminar flow occurs when the Reynolds number is approximately:

Accepted Answer

Less than 2,300

Answer

Laminar flow is characterized by smooth, parallel streamlines and occurs when the Reynolds number is below approximately 2,300, indicating viscous forces dominate over inertial forces.

Question 2

Absolute pressure is related to gauge pressure by:

Accepted Answer

Absolute = Gauge + Atmospheric

Answer

Absolute pressure is the total pressure including atmospheric pressure, so Absolute = Gauge + Atmospheric (≈ 101,325 Pa at sea level).

Question 3

Cavitation in a hydraulic system occurs when:

Accepted Answer

Local fluid pressure drops below the vapor pressure of the fluid

Answer

Cavitation occurs when local pressure in a flowing fluid drops below its vapor pressure, causing vapor bubbles to form; when these collapse, they can cause severe damage to pump impellers and pipes.

Question 4

The specific gravity of a fluid is defined as:

Accepted Answer

The ratio of its density to the density of water at 4°C

Answer

Specific gravity is a dimensionless ratio of a substance's density to the density of water (1,000 kg/m³ at 4°C), so water has a specific gravity of exactly 1.

Question 5

Head pressure in fluid systems refers to:

Accepted Answer

The equivalent height of fluid column that produces a given pressure

Answer

Head pressure expresses fluid pressure as an equivalent column height (h = P/ρg), allowing pressure to be visualized as a vertical distance the fluid could be raised.

NAPT - Navy Advanced Programs Test Practice Test

NAPT - Navy Advanced Programs Test Practice Test

NAPT Fluid Mechanics and Hydraulics 2