## IES 2017 | Fluid Mechanics Solved questions

Question #1

A section of a dam made of concrete, $\rho$ = 2.6, total height = 35m, with top walkway width of 6m, is shown. The upstream bottommost point is called the Heel of the dam. The sloped part on downstream side is 3 vertical on 2 horizontal. Water stands till 2 m short of the top of the dam section. The net resultant force acting on the base level of the dam is nearly. (A) 1370 k kgf

(B) 1385 k kgf

(C) 1400 k kgf

(D) 1433 k kgf

Question #2

A Spherical waterdrop of 1 mm in diameter splits up in air into 64 smaller drops of equal size. The surface tension coefficient of water in air is 0.073 N/m. The work required in splitting up the drop is

(A) 0.96×10-6 J

(B) 0.69×10-6 J

(C) 0.32×10-6 J

(D) 0.23×10-6 J

Question #3

Consider the following statements:
1. At low Reynolds numbers of any flow, viscous forces dominate over inertial forces.

2. Transition from laminar to turbulent flow occurs over a range of Reynolds numbers depending on the surface presented to the flow.

Which of the above statements is/are correct?

(A) 1 only

(B) 2 only

(C) Both 1 and 2

(D) Neither 1 nor 2

Question #4

Consider the following statements pertaining to stability of floating bodies:

1. A floating body will be stable when the centre of gravity is above the centre of buoyancy.

2. The positions of metacentres corresponding to different axes of rotation are generally different for the same floating object.

3. For cargo ships, the metacentric height varies with loading.

Which of the above statements are correct?
(A) 1, 2 and 3

(B) 1 and 2 only

(C) 1 and 3 only

(D) 2 and 3 only

Question #5

Water is coming out from a tap and falls vertically downwards. At the tap opening, the stream diameter is 20 mm with uniform velocity of 2 m/s. Assuming steady inviscid flow, constant pressure atmosphere everywhere, and neglecting curvature and surface tension effects, the diameter of the stream 0.5m below the tap opening is nearly.

(A) 11.7 mm

(B) 14.6 mm

(C) 17.5 mm

(D) 20.4 mm

Question #6

An oil flows through a pipe at a velocity of 1.0 m/s. The pipe is 45m long and has 150mm diameter. What is the head loss due to friction, if $\rho$ = 869kg / m3 and $\mu$ = 0.0814kg / m s?

(A) 0.61 m

(B) 0.51 m

(C) 0.41 m

(D) 0.31 m

Question #7

In a steady laminar flow of a given discharge through a circular pipe of diameter D, the head loss is proportional to

(A) D–1

(B) D–2

(C) D–3

(D) D–4

Question #8

A two dimensional flow field is defined as V = ix − jy. The equation of the stream line passing through the point (1, 2) is

(A) xy + 2 =0

(B) x2y+2=0

(C) xy–2=0

(D) x2y–2=0

Question #9

The centre – line velocity in a pipe flow is 2m/s. What is the average flow velocity in the pipe if the Reynolds number of the flow is 800?

(A) 2 m/s

(B) 1.5 m/s

(C) 1 m/s

(D) 0.5 m/s.

Question #10

Which of the following statements are correct?

1. The specific speed of a turbine is the speed at which a homologous turbine develops 1 mhp under unit head at its maximum efficiency.

2. The specific speed is a dimensionless parameter used for the selection of turbines.

3. The function of guide vanes in reaction turbines is to minimize shock at entry of the fluid onto the runner blades.

Select the correct answer using the code given below.

(A) 1, 2 and 3

(B) 2 and 3 only

(C) 1 and 2 only

(D) 1 and 3 only

Question #11

A centrifugal pump lifts 0.0125 m3/s of water from a well with a static lift of 30m. If the brake power of the driving electric motor is 5 kW, what is the overall efficiency of the pump-set?

(A) 57.6%

(B) 63.9%

(C) 65.3%

(D) 73.6%

Question #12

A jet of water issues from a sharp-edged vertical orifice under a constant head of 0.51m. At a certain point of the issuing jet, the horizontal and vertical coordinates measured from vena contracta are 0.406 m and 0.085m, respectively. What is the value of the coefficient of velocity?
(A) 0.975

(B) 0.925

(C) 0.875

(D) 0.825

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