## CE203 Fluid Mechanics

## Model Question Paper Set2

__PART A__

1) a. A venturimeter 30 cm x 10 cm is used for measuring the discharge of oil (specific gravity=0.85) passing through a vertical pipe in upward direction.

The difference between the entrance and throat section of the venturimeter is 40 cm.

The reading recorded by mercury manometer is 20 cm. Find the discharge and pressure difference between the

entrance and throat section. Take Cd = 0.97 [8 Marks]

b. Find the discharge through a trapezoidal notch which is 1 m wide at the top and 0.40 m at the bottom and is 30 cm in height.

The head of water on the notch is 20 cm. Assume Cd for rectangular portion as 0.62 while for triangular portion 0.60. [7 Marks]

2) a. In a 45 0 bend a rectangular air duct of 1 m 2 cross-sectional area is gradually reduced to 0.5 m 2 area.

Find the magnitude and direction of the force required to hold the duct in position if the velocity of flow at the 1 m 2 section is 10 m/s, and pressure is 2.943 N/cm 2 .

Take density of air as 1.16 kg/m 3 . [8 Marks]

b. Explain the experimental determination of hydraulic coefficients. [7 Marks]

__PART B__

__(Answer any 2 questions out of 3 questions – 20 Mark each)__

3) a. An oil of viscosity 10 poise flows between two parallel fixed plates which are kept at a distance of 50 mm apart.

Find the rate of flow of oil between the plates if the drop of

pressure in a length of 1.2 m be 0.3 N/m 2 . The width of the plates is 200 mm. [10 Marks]

b. Find the displacement thickness, the momentum thickness and energy thickness for the velocity distribution in the boundary layer given by where u is the velocity at a distance y from the plate and u = U at y = , where boundary layer thickness. [10 Marks]

4) a. A horizontal pipe of diameter 500 mm is suddenly contracted to a diameter of 250 mm.

The pressure intensities in the large and smaller pipe is given as 13.734 N/cm 2 and 11.772 N/cm 2 respectively.

Find the loss of head due to contraction if C c = 0.62. Also determine the rate of flow of water. [10 Marks]

b. A plate of 600 mm length and 400 mm wide is immersed in a fluid of sp. gr.0.9 and kinematic velocity () 10 -4 m 2 /s.

The fluid is moving with a velocity of 6 m/s.

Determine (i) boundary layer thickness, (ii) shear stress at the end of the plate, and (iii) drag force on one side of the plate. [10 Marks]

5) a. The rate of flow of water pumped into a pipe ABC, which is 200 m long, is 20 litres/s.

The pipe is laid on an upward slope of 1in 40. The length of the portion AB is 100 m and its diameter 100 mm, while the length of the portion BC is also 100 m but its diameter is 200mm.

The change of diameter at B is sudden. The flow is taking place from A to C, where the pressure at A is 19.62 N/cm 2 and end C is connected to a tank.

Find the pressure at C and draw the hydraulic gradient and total energy line. Take f= 0.008 [10 Marks]

b. Explain the growth of boundary layer over long thin plate. [10 Marks]

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