FLUID PROPERTIES



FLUID PROPERTIES

1. Calculate the density, specific weight and weight of one litre of petrol of specific gravity is 0.7.

Viscosity

2. The velocity distribution over a plate is given by u = (3/4)*y-y2 where u is velocity in m/s and at a depth y in m above the plate. Determine the shear stress at a distance of 0.3 m from the top of plate. Assume dynamic viscosity of the fluid is taken as 0.95N s/m2.

3. The space between two square flat parallel plates is filled with oil. Each side of the plate is 60 cm. The thickness of the oil film is 12.5 mm. The upper plate, which moves at 2.5 m/s requires a force of 98.1 N to maintain the speed. Determine the dynamic viscosity of the oil and the kinematic viscosity of the oil in stokes if the specific gravity of the oil is 0.95.

4. A 400 mm diameter shaft is rotating at 200 r.p.m. in a bearing of length 120 mm. If the thickness of oil film is 1.5 mm and the dynamic viscosity of the oil is 0.7 N.s/m2 determine : (i) Torque required to overcome friction in bearing (ii) Power utilised in overcoming viscous resistance.

5. A vertical cylinder of diameter 180 mm rotates concentrically inside another cylinder of diameter 181.2 mm. Both the cylinders are 300 mm high. The space between the cylinders is filled with a liquid. Determine the viscosity of the fluid if a torque of 20 Nm is required to rotate the inner cylinder at 120 r.p.m.

6. A plate 0.05 mm distant from a fixed plate, moving at 1.2 m/s requires a force of 2.2 N/m2 to maintain this speed. Find the dynamic viscosity of fluid between the plates.

Surface tension &Capillarity

7. Find the surface tension in a soap bubble of 40 mm diameter when the inside pressure is 2.5 N/m2 above atmospheric pressure.

8. Calculate the capillary rise in a glass tube of 4 mm diameter, when immersed in (i) water, and (ii) mercury.the temperature of the liquid is 20oC and the values of the surface tension of water and mercury at 20oC in contact with air are 0.073575 N/m and 0.51 N/m respectively. The angle of contact for water is zero that for mercury 130o. Take density of water at 20oC as equal to 998 kg/m3.

9. Determine the minimum size of glass tube that can be used to measure water level, if the capillary rise in the tube is not to exceed 2 mm. Take surface tension of water in contact with air as 0.073575 N/m.

Continuity equation

10. A pipe (1) 450 mm in diameter branches in to two pipes (2 and 3) of diameters 300 mm and 200 mm respectively. If the average velocity in 450 mm diameter pipe is 3m/s. Find (i) Discharge through 450 mm diameter pipe; (ii) Velocity in 200 mm diameter pipe if the average velocity in 300mm pipe is 2.5 m/s.

11. In a three-dimensional in compressible fluid flow, the velocity components in x and y-directions are: u=x2+y2z3; v=-(xy+yz+zx). Use continuity equation to evaluate an expression for the velocity component w in the z-direction.

Bernoulli’s equation (Energy Equation)

12. A 6m long pipe is inclined at an angle of 20o with the horizontal. The smaller section of the pipe which is at lower level is of 100 mm dia and the larger section is of 300 mm dia. If the pipe is uniformly tapering and the velocity of the water at the smaller section is 1.8m/s. Determine the difference of pressures between two sections.

Venturimeter

13. A 30 cm x 15 cm venturimeter is provided in a vertical pipe line carrying oil of specific gravity 0.9, the flow being upwards. The difference in elevation of the throat section and entrance section of the venturimeter is 30 cm. The differential U tube mercury manometer shows a gauge deflection of 25 cm. Calculate: (i) the discharge of oil. (ii) The pressure difference between the entrance section and the throat section. Take Cd=0.98 and specific gravity of mercury as 13.6.

14. A horizontal venturimeter with inlet and throat diameter 300 mm and 100 mm respectively is used to measure the flow of water. The pressure intensity at inlet is 130 kN/m2 while the vacuum pressure head at throat is 350 mm of mercury. Assuming that 3% head lost between the inlet and throat. Find the value of coefficient of discharge for the venturimeter and also determine the rate of flow.

Orifice Meter

15. An orifice meter with orifice diameter 15 cm is inserted in a pipe of 30 cm diameter. The pressure difference measured by a mercury oil differential manometer on the two sides of the orifice meter gives a reading of 50 cm of mercury. Find the rate of flow of oil of sp.gr 0.9 and Cd = 0.6.

Momentum Equation

16. A 45o reducing bend is connected in a pipe line, the diameters at the inlet and outlet of the bend being 600 mm and 300 mm respectively. Find the force exerted by water on the bend if the intensity of pressure at inlet to bend is 8.829 N/cm2 and rate of flow of water is 600 liters/s.

17. A 300 mm diameter pipe carries water under a head of 20 m with a velocity of 3.5 m/s. if the axis of the pipe turns through 45o, find the magnitude and direction of the resultant force at the bend.

Moment of Momentum Equation

18. A lawn sprinkle has 0.8 cm diameter nozzle at the end of a rotating arm and discharge water at the rate of 10 m/s velocity. Determine the torque required to hold the rotating arm stationary. Also determine the constant speed of rotation of the arm, if free to rotate.

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