HYDRAULICS AND HYDRAULIC MACHINERY, November 2008
(Electrical & Electronic Engineering)
1. (a) Define mass density, weight density, specific volume and specific gravity.
(b) A 30 cm diameter shaft revolves in a guide bearing of 60 cm long at 500 rpm. If the oil film bearing is 0.13 mm and viscosity of oil is 0.05Ns/m2, find the power absorbed.
2. (a) Briefly explain the classification of flows.
(b) What type of acceleration is to be expected if
i. Streamlines are parallel and equidistant
ii. Streamlines are straight and converging
iii. Streamlines are curved but equispaced
iv. Streamlines are curved and converging.
3. (a) Water is pumped at the rate of 0.5m3/s through a 30cm diameter pipe upto a hill top. Hill top has an elevation of 50m, and the diameter of the pipe line reduces to 20cm. If the pump maintains a pressure of 9810N/m2 at hill top, what is the pressure at the foot of the hill ? What is the power required to pump the water.
(b) A pipe of 300mm diameter conveying 0.3m3/s of water has a right angled bend in a horizontal plane. Find the resultant force exerted on the bend if the pressure at inlet and outlet of the bend are 25N/cm2 and 23N/cm2.
4. (a) Derive Dupit’s equation for an equivalent pipe
(b) Three pipes of 400mm, 200mm and 300mm diameters have lengths of 400mm,
200mm and 300mm respectively. They are connected in series to make a compound pipe. The ends of this compound pipe are connected with two tanks where difference of water levels is 16m. Assume the friction factor as 0.005. Determine the discharge through the compound pipe neglecting minor losses.
5. Determine the diameter of the throat of a venturimeter to be introduced in a horizontal section of a 0.10m diameter main so that reading of the differential U-tube manometer is 0.60m of mercury when the discharge is 20 litres per second. Assume the coefficient of discharge of the meter as 0.95.
6. A jet water, 10 cm diameter and having a velocity of 15 m/s impinges at the center
of a hemispherical vane. The linear velocity of the vane is 5 m/s in the direction of the jet. Find the force exerted on the vane. How this force would change if the jet impinges on series of vanes attached to the circumference of a wheel?
7. The hub diameter of a Kaplan turbine working under a head of 12 m is 0.35 times the diameter of the runner. The turbine is running at 100 rpm. If the vane angle at the extreme edge of the runner at exit is 150 and flow ratio is 0.6, find:
(a) Diameter of the runner
(b) Discharge through the runner
8. A double acting reciprocating pump has a stroke of 25 cm and piston diameter of
12.5 cm. The center of the pump is 4m above the level of water in the sump and 30m below the delivery water level. The lengths of suction and delivery pipes are 6 m and 35 m respectively and their diameters are both 6 cm. If the pump is running at 30 rpm, estimate the pressure head developed on the piston in m of water at
(a) the beginning of the suction stroke,
(b) the middle of suction stroke, and
(c) the end of suction stroke.
If the mechanical efficiency is 80%, determine the power required to drive the pump. Take atmospheric pressure as 10.3 m of water and 4f = 0.04.