Free Fluid Flow Operations MCQs with Answers

• A. Pitot tube
• B. Hot wire anemometer
• C. Segmental orificemeter
• D. Rotameter

Explanation: A hot-wire anemometer measures gas velocity from the cooling effect of the flow on a heated wire and is especially sensitive at low…

• A. A disturbance travelling upstream in moving fluid
• B. Flow in an open channel
• C. An elementary wave in an open channel
• D. None of these

Explanation: The propagation of sound in a gas is a small-amplitude pressure disturbance, analogous to an elementary wave travelling through an open…

• A. 5
• B. 14.1
• C. 56.22
• D. 28.2

Explanation: The Pitot reading gives dynamic pressure: one-half rho_air times velocity squared equals rho_water g h.

• A. Decreases
• B. Remain constant
• C. Increases exponentially
• D. Increases linearly

Explanation: For a stationary incompressible fluid, hydrostatic balance gives p = p0 + rho g h.

• A. Venturimeter
• B. Orificemeter
• C. Flow nozzle
• D. All of them incur the same head loss

Explanation: An orifice meter creates strong flow contraction and separation, causing the greatest permanent energy loss.

• A. Inverse of the radial distance
• B. Radial distance linearly
• C. Square of the radial distance
• D. Elevation along vertical direction

Explanation: For rigid-body rotation, radial force balance gives dp/dr = rho omega²r.

• A. Rotation
• B. Translation
• C. Linear deformation
• D. Angular deformation

Explanation: Angular deformation occurs when the angle between two initially adjacent sides of a fluid element changes.

• A. Fluid to that of the sound
• B. Light to that of the fluid
• C. Fluid to that of the light
• D. Sound to that of the fluid

Explanation: Mach number compares a fluid’s velocity with the local speed of sound, so it is defined as fluid speed divided by sound speed.

• A. Specific gravity & temperature of the liquid
• B. All A., B. and C.
• C. Frictional resistance through pipes, fittings & passages
• D. Leakage & pressure decreasing at higher elevations

Explanation: The actual lift is reduced by leakage, friction in pipes and fittings, and changes in liquid pressure caused by elevation, while liquid…

• A. Axial flow
• B. None of these
• C. Mixed flow
• D. Centrifugal

Explanation: Low specific speed indicates a radial-flow, or centrifugal, pump. Axial-flow pumps have high specific speed, while mixed-flow pumps lie…

• A. Reduce discharge fluctuation
• B. Reduce the danger of cavitation
• C. Avoid the necessity of priming
• D. Increase the pump efficiency

Explanation: An air vessel stores liquid during part of the stroke and releases it during another part, smoothing the pulsating discharge of a…

• A. N2D3
• B. ND2
• C. N3D5
• D. N2D

Explanation: From the pump affinity laws, flow varies as ND³ and head as N²D²; power, being proportional to flow multiplied by head, varies as N³D⁵.

• A. Fluid on the solid in a direction opposite to flow
• B. None of these
• C. Solid on the fluid
• D. Fluid on the solid in the direction of flow

Explanation: For a stationary solid in a flowing fluid, drag acts on the solid in the direction of fluid flow, opposing the relative motion of the…

• A. gm/cm. sec
• B. gm/cm2. sec
• C. cm2/sec
• D. m2/sec

Explanation: Dynamic viscosity has dimensions mass divided by length-time; in CGS units, one poise equals 1 g/(cm·s).

• A. Conversion of kinetic head to pressure head is facilitated
• B. Both B. and C.
• C. Power transmitted through the nozzle is maximum, when the head lost due to friction in the
• D. pipe is equal to one third of the total supply head
• E. Conversion of pressure head to kinetic head is facilitated

Explanation: A nozzle converts pressure head into velocity head, so it increases the exit velocity.

• A. Reciprocating compressor
• B. Axial flow compressor
• C. Blower
• D. Centrifugal compressor

Explanation: A blower produces gas flow with a relatively small pressure rise, so substantial compression is not required.

• A. Weber
• B. Mach
• C. Froude
• D. Reynold

Explanation: The Reynolds number is the ratio of inertial forces to viscous forces, Re = ρvD/μ.

• A. Linearly as the viscosity
• B. Inversely as the viscosity
• C. Inversely as the pressure drop
• D. As the square of the radius

Explanation: For laminar flow in a round tube, the Hagen–Poiseuille equation gives Q = πR⁴ΔP/(8μL), so discharge is inversely proportional to…

• A. Not a function of the roughness of pipe wall
• B. Inversely proportional to Reynolds number
• C. Both A. & B.
• D. Neither A. nor B.

Explanation: For fully developed laminar flow in a circular pipe, the Fanning factor is f = 16/Re, so it is inversely proportional to Reynolds number.

• A. A storage device and a control valve
• B. Two pistons and two cylinders
• C. A cylinder and a plunger
• D. A storage tank and a ram pump

Explanation: A hydraulic accumulator stores pressurized liquid using a cylinder and plunger arrangement, with the plunger moving as liquid enters or…