JNTU Exam Papers, B -Tech I Sem ,Fluid mechanics and hydraulic machinery -February 2008
JNTU Exam Papers
B.Tech I Semester Supplimentary Examinations, February 2008
FLUID MECHANICS AND HYDRAULIC MACHINERY
(Electrical & Electronic Engineering)
1. (a) The pressure at a point in a fluid is 13.6 cm of mercury vacuum. Express it in N/m2 of absolute pressure, gauge pressure and also in metres of water.
(b) A 6 m deep tank is square in plan of size 2 m x 2 m. It contains water up to a depth of 4 m and oil of relative density 0.88 for the remaining height of 2 m. Determine the pressure on the bottom of the tank.
2. (a) Derive the equation of continuity for one dimensional flow of an incompressiblefluid.
(b) Explain the terms:
i. Path line
ii. Stream line
iii. Streak line.
3. (a) Describe major and minor losses in pipe flow in detail.
(b) Discuss how friction factor various with Reynolds Number.
(c) Two pipes one of 10cm diameter, 200m long and another 15cm diameter, 400m long are connected in parallel. The friction factors are 0.0075 for the smaller pipe and 0.006 for the large pipe. The total discharge through the system is 50 lit/sec. Find the discharge and head loss in each pipe. Neglect minor losses. Calculate the equivalent length of a 20cm diameter having f=0.005.
4. (a) What do you mean by impact of jet. Explain
(b) Derive an expression for force exerted by the jet on a stationary vertical plate.
(c) A 10cm diameter jet of water exerts a force of 2 KN in the direction of flow
against a stationary flat plate which is inclained at an angle of 300 with the
axis of the stream. Find
i. Force normal to the plate
ii. velocity of the jet
iii. mass flow rate of water Kg/sec.
5. (a) What are the elements of hydroelectric power stations? Write elaborately about any two of them with neat sketches.
(b) A turbine with an efficiency of 90% is to installed in a hydroelectric plant. The head and discharge available at the plant are 40m and 25m3/sec respectively. The turbine has to run at 120rpm. What is the power developed and what is the type of turbine based on specific speed.
6. (a) What are the working proportions of a Kaplan turbine ? Explain why draft tube is provided for a Kaplan turbine when compared with a Pelton wheel.
(b) An inward flow reaction turbine has inlet and outlet diameters of 1.2m and 0.6 m respectively. The breadth at inlet is 0.25 m and at outlet it is 0.35m. The runner speed is 250 rpm. The relative velocity at inlet is 3.5m/sec and is radial. Determine
i. the absolute velocity at inlet and its inclination to the tangent of runner
ii. Discharge and
iii. the velocity of flow at outlet.
7. (a) Define unit power and unit speed and derive the equations for the same. What are their uses ?
(b) What is a surge tank and what are the uses of it in a hydropower turbine installation ? Explain where and how it is located with the help of a neat sketch.
8. (a) Define slip and coefficient of discharge of a reciprocating pump and write the expressions for the same. What do they practically indicate?
(b) The following details refer to working of a single acting reciprocating pump. Find the slip, coefficient of discharge and theoretical power required to drive the pump.
Piston diameter = 15 cm
Crank radius = 15 cm
Diameter of delivery pipe = 10 cm
Discharge of the pump = 0.31 m3 /min
Total lift = 15 m
Speed of the pump = 60 rpm