Sunday, December 27, 2020

GATE Chemical Engineering Questions and Answers-Fluid Mechanics

Viscosity of water at 40°C lies in the range of

(A) 1×10-3 – 2×10-3 kg/(m.S)

(B)  0.5×10-3 – 1×10-3 kg/(m.S)

(C)  1 – 2 kg/(m.S)

(D) 0.5 – 1 kg/(m.S)

                                                                                                      GATE 2004

Answer:          (B)

 

For the manometer setup shown in the figure, the pressure difference PA – PB is given by

GATE 2004


(A)             H – ρair)gH

(B)              H – ρL)gH

(C)              ρH – ρL)gH + (ρL - ρair)g(L-H)

(D)             H - ρL)gL + (ρL - ρair)gH

                                                                                                      GATE 2004

Answer:          (A)

 

A conical tank with a bottom opening of cross sectional area A is filled with water and is mounted on supports, as shown in the figure. What is the force F with which plate X must be pushed up to prevent water from leaking? Assume that the density of air is negligible as compared to the density of water .

GATE 2004


(A)             ρLVg

(B)              ρLAHg

(C)              ρLVg/2

(D)             ρLVg/3

                                                                                                      GATE 2004

Answer:          (B)

 

Three piping networks as shown in the figure are placed horizontally. They are made using identical pipe segments and are subjected to the same pressure drop across them. Assuming no pressure losses at junction, the flow rates across the three networks are related as Q1 : Q2 : Q3

GATE 2004


GATE 2004







                                                                                                      GATE 2004

Answer:          (C)

 

For a particle settling in water at its terminal settling velocity, which of the following is true?

(A)             Buoyancy = weight + drag

(B)              weight = Buoyancy + drag

(C)              drag = Buoyancy + weight

(D)             drag = weight

                                                                                                      GATE 2004

Answer:          (B)

 

The equivalent diameter for flow through a rectangular duct of width B and height H is

(A)            HB/2(H+B)

(B)            HB/(H+B)

(C)             2HB/(H+B)

(D)             4HB/(H+B)

                                                                                                      GATE 2004

Answer:          (C)

 

What is the force required (in newtons) to hold a spherical balloon stationary in water a depth of H from the air-water interface? The balloon is of radius 0.1 m and is filled with air

(A)            4ᴨg/3

(B)            0.1ᴨgH/4

(C)             0.1ᴨgH/8

(D)            0.04ᴨgH/3

                                                                                                      GATE 2004

Answer:          (A)

 

A lubricant 100 times more viscous than water would have a viscosity (in Pa-s)

(A)       0.01

(B)       0.1

(C)       1

(D)       10

                                                                                                            GATE 2003

Answer:          (B)

 

The velocity profile for a Bingham plastic fluid flowing (under laminar conditions) in a pipe is

(A)       parabolic

(B)       flat

(C)       flat near the wall and parabolic in the middle

(D)       parabolic near the wall and flat in the middle

                                                                                                            GATE 2003

Answer:          (D)

 

The variables required to be known in correlations used for estimating the horse power of a centrifugal gas compressor and hence its cost are

P:         inlet pressure

Q:        compressor RPM

R:        delivery pressure

S:         volumetric flow rate at inlet

(A)       P, Q and R

(B)       P and R

(C)       R and S

(D)       P, R and S

                                                                                                            GATE 2003

Answer:          (D)

 

A fluid element has a velocity V = -y2x i + 2yx2 j. The motion at

GATE 2003

is

(A)       rotational and incompressible

(B)       rotational and compressible

(C)       irrotational and compressible

(D)       irrotational and incompressible

                                                                                                            GATE 2003

Answer:          (A)

 

A pipe has a porous section of length L as shown in the figure. Velocity at the start of this section is Vo. If fluid leaks into the pipe through the porous section at a volumetric rate per unit area q (x/L)2, what will be the axial velocity in the pipe at any x? Assume incompressible one-dimensional flow i.e., no gradients in the radial direction

GATE 2003


GATE 2003


                                                                                                            GATE 2003

Answer:          (D)

 

A centrifugal pump is used to pump water through a horizontal distance of 150 m and then raised to an overhead tank 10 m above. The pipe is smooth with an I.D. of 50 mm. What head (m of water) must the pump generate at its exit (E) to deliver water at a flow rate of 0.001 m3/s? The Fanning friction factor, f is 0.0062.

GATE 2003


(A)       10 m

(B)       11 m

(C)       12 m

(D)       20 m

                                                                                                            GATE 2003

Answer:          (B)

 

Match the following dimensionless numbers with the appropriate ratio of forces

List I (Dimensionless Number)

P.         Froude Number

Q.        Reynolds Number

R.        Friction factor

S.         Nusselt Number

List II (Ratio of forces)

1.         Shear force / inertial force

2.         Convective heat transfer / conductive heat transfer

3.         Gravitational force / viscous force

4.         Inertial force / viscous force

5.         Inertial force / gravitational force Codes

(A)       P-1, Q-2, R-5, S-3

(B)       P-5, Q-4, R-3, S-2

(C)       P-5, Q-4, R-1, S-2

(D)       P-3, Q-4, R-5, S-1

                                                                                                GATE 2003

Answer:          (C)

 

Common statement for the next two questions

A bed of spherical particles (sp. gravity 2.5) of uniform size 1500 μm is 0.5 m in diameter and 0.5 m high. In the packed bed state, the porosity may be taken as 0.4. Ergun’s equation for the above particle-fluid system (in SI units) is given below

GATE 2003

If water is to be used as the fluidizing medium, the minimum fluidization velocity, VOM is

(A)       12 mm/s

(B)       16 mm/s

(C)       24 mm/s

(D)       28 mm/s

                                                                                                GATE 2003

Answer:          (B)

 

In actual operation, the above bed has a height = 1m. What is the porosity of the fluidized bed?

(A)       0.2

(B)       0.5

(C)       0.7

(D)       0.8

                                                                                                GATE 2003

Answer:          (C)

 

The pressure differential across a vertical venture meter (shown in Figure) is measured with the help of a mercury manometer to estimate flow rate of water flowing through it. The expression for the velocity of water at the throat is

(given: density of Hg is ρm density of Hg is ρw)

GATE 2003


GATE 2003









                                                                                                                                                    GATE 2003

Answer:          (B)


With increasing the flow rate, the hydraulic efficiency of a centrifugal pump

(A)             Monotonically increases

(B)              Decreases and then increases

(C)              Remains constant

(D)             Increases and then decreases

                                                                                                      (GATE 2002)

Answer:          (B)

 

For flow past a flat plate, if x is the distance along the plate in the direction of flow, then boundary layer thickness is proportional to

GATE 2002








                                                                                                      (GATE 2002)

Answer:          (A)

 

For turbulent flow of an incompressible fluid through a pipe, the flow rate Q is proportional to (ΔP)n where ΔP is the pressure drop. The value of exponent ‘n’ is

(A)             1

(B)              0

(C)              <1

(D)             >1

                                                                                                      (GATE 2002)

Answer:          (C)

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