ETC Hydraulics & Fluid Mechanics Flashcards

The Reynolds number is used in fluid mechanics to determine whether flow is:

Answer: Laminar or turbulent

The Reynolds number (Re = ρVD/μ) distinguishes laminar flow (Re 4,000) in circular pipe systems.

A Venturi meter measures which hydraulic quantity?

Answer: Flow rate by measuring a pressure differential at a constriction

A Venturi meter calculates volumetric flow rate by measuring the pressure drop between the inlet and the narrow throat section, then applying Bernoulli's equation.

The Darcy-Weisbach equation (hf = f × L/D × V²/2g) is used to calculate:

Answer: Head loss due to pipe wall friction

The Darcy-Weisbach equation calculates major (friction) head loss in a pipe, requiring the Darcy friction factor f, pipe length L, diameter D, and flow velocity V.

The Hydraulic Grade Line (HGL) in a pipe system represents the sum of:

Answer: Pressure head and elevation head

The HGL equals the sum of pressure head (P/γ) and elevation head (z) at each cross-section, and represents the height to which water would rise in a piezometer.

A manometer is an instrument primarily used to measure:

Answer: Pressure or differential pressure between two points

A manometer measures pressure or pressure differences by observing the height difference of a fluid column (commonly water or mercury) in a U-tube.

Cavitation in hydraulic pumps occurs when:

Answer: Local fluid pressure drops below the fluid's vapor pressure

Cavitation forms vapor bubbles when local pressure falls below the vapor pressure; these bubbles collapse violently near the impeller, causing noise, vibration, and surface erosion.

Minor losses in a piping system are caused by:

Answer: Fittings, valves, bends, and abrupt geometry changes

Minor losses result from flow disruptions at fittings, elbows, tees, valves, and contractions/expansions, calculated as hm = K × V²/2g using a loss coefficient K.