Free Fluid Flow Operations MCQs with Answers

• A. As square of
• B. Inversely as square root of
• C. Inversely as
• D. Directly as

Explanation: At fixed speed and capacity, fan pressure rise is proportional to gas density, and the power requirement is also proportional to density.

• A. All A., B. and C.
• B. Capacity is reduced
• C. Requires more power
• D. Develops a lower head

Explanation: Higher viscosity increases internal friction and reduces a centrifugal pump's capacity and developed head, while increasing the power…

• A. Δp
• B. > Δp
• C. < Δp
• D. Δp2

Explanation: A globe valve has a more tortuous flow path and causes much greater irreversible loss than a streamlined gate valve.

• A. Reynolds number at the orifice
• B. Both A. and B.
• C. Ratio of orifice dia to pipe dia
• D. None of the above parameters, and has a constant value of 0.61

Explanation: The discharge coefficient depends mainly on the Reynolds number and the diameter ratio, β = d_orifice/d_pipe.

• A. That is traced by all the fluid particles passing through a given point
• B. Along which a fluid particle travels
• C. Such that at every point on it, the velocity is tangential to it
• D. None of these

Explanation: A streamline is defined so that the local fluid velocity is tangent to it at every point.

• A. Total energy
• B. Total pressure
• C. Velocity head
• D. None of these

Explanation: For steady, frictionless flow with no shaft work or heat effects, the sum of pressure, velocity, and elevation energies remains constant.

• A. Fluid particles move in an orderly manner
• B. Shear stresses are generally larger than in a similar laminar flow
• C. Shear stress is caused more effectively by cohesion than momentum transfer
• D. Momentum transfer is on molecular scale only

Explanation: Turbulent eddies transport momentum across layers in addition to molecular action, producing greater effective momentum transfer and…

• A. Very precise control of
• B. Multidirectional
• C. Unidirectional
• D. None of these

Explanation: A check valve permits flow in one direction and automatically closes when flow reverses.

• A. For Reynolds number greater than 300
• B. None of these
• C. For unbaffled tank
• D. When there is no vortex formation

Explanation: The Froude number compares inertial and gravitational effects and is important when a free surface can deform, such as during vortex…

• A. Reciprocating
• B. Centrifugal
• C. Volute
• D. Rotary vacuum

Explanation: Reciprocating pumps deliver relatively small flow rates at high pressures because their positive-displacement action can generate large…

• A. H1/2
• B. H3/2
• C. H2/5
• D. H5/2

Explanation: For a rectangular weir, integration of the elemental strip flow gives Q = (2/3)C_d b√(2g)H^(3/2). Thus discharge varies as H^(3/2).

• A. Velocity head
• B. Pressure
• C. None of these
• D. Point velocity

Explanation: A Venturimeter uses the pressure difference between its inlet and throat to determine flow rate or discharge, rather than measuring…

• A. Density does not change with pressure & temperature
• B. Compressibility is greater than zero
• C. Temperature remains constant
• D. Is frictionless

Explanation: Incompressible flow assumes that fluid density remains essentially constant despite changes in pressure and temperature.

• A. Rubber latex
• B. Sewage sludge
• C. Blood
• D. Sugar solution

Explanation: Sewage sludge behaves as a Bingham or ideal plastic fluid: it requires a yield stress before flowing and then shows approximately…

• A. Diameter & friction factor
• B. Length & friction factor
• C. Fluid flow rate & friction loss
• D. Length & diameter

Explanation: Equivalent piping systems carry the same flow rate with the same frictional pressure or head loss under comparable conditions.

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

Explanation: The Weber number compares inertial forces with surface-tension forces, typically written as We = ρv²L/σ.

• A. Corresponding to uniform flow
• B. Measured normal to the channel bed
• C. Corresponding to steady flow
• D. None of these

Explanation: Normal depth is the depth corresponding to uniform open-channel flow, where the depth and velocity remain constant along the channel.

• A. d1/3
• B. √d
• C. d2
• D. d2/3

Explanation: For laminar flow over a flat plate, boundary-layer thickness varies approximately as δ ∝ √x, where x is the distance from the leading…

• A. Creep
• B. Streamline
• C. Potential
• D. Boundary layer

Explanation: Potential flow is an ideal flow with zero vorticity and, for an inviscid fluid, no shear stress.

• A. Molten sodium (used as a coolant in Fast Breeder Reactor)
• B. Moderately viscous vegetable oil used in soap industry
• C. None of the above
• D. Thick molten soap at 80°C

Explanation: Centrifugal pumps are poorly suited to very viscous materials because viscosity causes large friction losses and reduces efficiency and…