Free Fluid Flow Operations MCQs with Answers

• A. 600
• B. 660
• C. 1.1
• D. 60

Explanation: For a positive-displacement pump under comparable conditions, volumetric flow is approximately proportional to speed.

• A. Inlet tip of a blade curves in a direction opposite to that
• B. Outlet tip of a blade is towards the direction
• C. Inlet tip of a blade is towards the direction
• D. Outlet tip of a blade curves in a direction opposite to that

Explanation: A forward-curved impeller has its outlet blade tip bent in the same direction as the impeller's rotation.

• A. < 5
• B. > 1
• C. < 1
• D. None of these

Explanation: Stokes' law assumes creeping flow around the particle, for which the particle Reynolds number is less than 1.

• A. 0.5
• B. 5
• C. 50
• D. 500

Explanation: The turbulent entrance or transition length in a smooth pipe is commonly estimated as about 50 pipe diameters.

• A. Pressure
• B. Elevation
• C. Both A. & B.
• D. Neither A. nor B.

Explanation: In a sudden enlargement, the fluid slows down and part of its velocity head is recovered as static pressure head.

• A. 4.33 psi, 10 ft. of water, 8.83 inches of Hg
• B. 4.33 psi, 10 ft. of water, 20.7 inches of Hg
• C. 10 psi, 19.7 ft. of water, 23.3 inches of Hg
• D. 10 psi, 19.7 ft. of water, 5.3 inches of Hg

Explanation: Using 1 psi approximately equal to 2.31 ft of water, 4.33 psi gives about 10 ft of water; dividing the water head by the specific-gravity…

• A. f1 = f2
• B. f1 < f2
• C. f1 > f2
• D. Data not sufficient to relate f1 & f2

Explanation: At the same diameter, velocity, fluid, and length, both pipes have the same Reynolds number, but the rough pipe has greater relative…

• A. Velocity
• B. Turbulence
• C. Velocity head
• D. None of these

Explanation: Loss at a sudden contraction is expressed as a loss coefficient multiplied by the velocity head, commonly written as K v²/(2g).

• A. Momentum
• B. Both B. & C.
• C. Energy
• D. Mass

Explanation: The continuity equation is obtained by applying conservation of mass to fluid flowing through a control volume.

• A. Fluid viscosity
• B. Fluid density
• C. Surface tension
• D. Gravity forces

Explanation: A boundary layer forms because viscosity enforces the no-slip condition at the wall and creates strong velocity gradients near the…

• A. Directly proportional to
• B. Directly proportional to square of
• C. Inversely proportional to
• D. Inversely proportional to square of

Explanation: The Darcy-Weisbach relation gives head loss as h_f = f(L/D)(V²/2g), so with pipe and friction factor fixed, loss varies with the square of…

• A. Total flow rate is the sum of flow rate in
• B. Head loss is same through
• C. Rate of flow in each pipe is proportional to the length of
• D. Same rate of flow passes through

Explanation: For pipes connected in series, continuity requires the same flow rate to pass successively through every pipe.

• A. 0.5
• B. 1
• C. 1.5
• D. 2

Explanation: For a linear profile, u/U = y/δ, so the displacement thickness is ∫₀δ(1 − u/U)dy = δ/2.

• A. Remove the contaminant present in the liquid
• B. Avoid priming, every time we start the pump
• C. Minimise the fluctuation in discharge
• D. Control the liquid discharge

Explanation: A foot valve is a non-return valve at the suction-pipe end that retains liquid when the pump stops.

• A. 1/μ
• B. μ2
• C. μ
• D. 1/μ2

Explanation: Newton's law states τ = μ(du/dy), so at a fixed rate of angular deformation, shear stress is directly proportional to viscosity μ.

• A. Fanning equation
• B. Blake-Plummer equation
• C. Hagen-Poiseuille equation
• D. Kozeny - Karman equation

Explanation: The Kozeny-Karman equation describes pressure drop through a packed bed in the laminar-flow regime.

• A. Static pressure
• B. Friction factor
• C. Dynamic pressure
• D. None of these

Explanation: A piezometer measures the liquid's static pressure head, since the liquid rises in the tube without a velocity-pressure contribution.

• A. ∝ Q
• B. Constant
• C. ∝ Q2
• D. ∝ √Q

Explanation: At a given float position, the float's effective weight and buoyancy are fixed, so the balancing drag force is constant.

• A. V-1
• B. V-0.8
• C. V
• D. V1.8

Explanation: For a dry packed bed, the combined viscous and inertial resistance gives a pressure-drop dependence commonly correlated approximately as…

• A. Hooke's law
• B. Newton's second law of motion
• C. Archimedes principle
• D. Newton's third law of motion

Explanation: Newton's law of viscosity relates shear stress to velocity gradient, while Hooke's law relates elastic stress to strain.