Power Engineering - Power Engineering
Exam Duration: 45 Mins Total Questions : 20
In an impulse turbine
- (a)
the entire kinetic energy is converted to pressure energy at the inlet to the turbine
- (b)
part of the kinetic energy is converted to pressure energy
- (c)
no part of pressure energy is converted to KE in the inlet
- (d)
the entire pressure energy is converted to velocity energy
In an inward flow reaction turbine, which of the following statements is correct?
- (a)
Water enters the outer periphery and moves radially inwards
- (b)
As speed increases, discharge increases
- (c)
Centrifugal head increases from inlet to outle
- (d)
All of the above
The function of guide vanes in a reaction turbine is
- (a)
to ensure shock less entry of water
- (b)
control flow rate of water on to the runner
- (c)
to guide the water at correct angle on to runner blades
- (d)
All of the above
Draft tube is fitted with the following purpose
- (a)
recover part of KE of water
- (b)
control the flow rate of water
- (c)
to guide water out of turbine
- (d)
avoid splashing of water
A pump converts
- (a)
mechanical energy to pressure energy
- (b)
pressure head to velocity head
- (c)
velocity head to pressure head
- (d)
Non- of the above
Cavitation occurs in centrifugal pumps due to
- (a)
very low suction pressure
- (b)
very high impeller speed
- (c)
Both (a) and (b)
- (d)
low discharge
A jet of water with velocity of 10 m/s strikes to a plate as shown in figure. Diameter of jet is 25 mm.
Then force required to apply at lower edge of plate to keep it vertical is
- (a)
28.7 N
- (b)
49.09 N
- (c)
24.5 N
- (d)
zero
A jet of water with velocity of 10 m/s strikes to a plate as shown in figure . Diameter of jet is 25 mm.
If P = 0, and Wplate= 10 g, then angle upto which plate swings freely
- (a)
60°
- (b)
90°
- (c)
30°
- (d)
45°
A Pelton turbine develops a power of 3600 kW at 400 rpm under a net head of 275 m. Its specific speed is
- (a)
18.29
- (b)
92.17
- (c)
89.43
- (d)
21.43
A Pelton wheel produces power 4000 kW under a head of 250 m.
If coefficient of velocity is 0.98, then velocity of jet is
- (a)
70 m/s
- (b)
92.31 m/s
- (c)
68.6 m/s
- (d)
50.09 m/s
A Pelton wheel produces power 4000 kW under a head of 250 m.
If nozzle area is 0.03 m2 then turbine efficiency is
- (a)
91%
- (b)
79%
- (c)
56%
- (d)
83%
In a Pelton wheel, a jet strikes to bucket with velocity 51.36 m/s and diameter of jet is 0.152 m. If jet ratio is 12 then speed of turbine is (assume maximum hydraulic efficiency)
- (a)
268 rpm
- (b)
670 rpm
- (c)
300 rpm
- (d)
890 rpm
In an inward flow reaction turbine discharge at outlet is radial. Velocity of flow at outlet is 2.5 m/s. If vane angle at outlet is 15 ° then speed of turbine is (given diameter at outlet is 0.6 m)
- (a)
301 rpm
- (b)
297 rpm
- (c)
310 rpm
- (d)
280 rpm
In a Francis reaction turbine, discharge from the runner is radial at outlet . Blade speed at inlet is 10 m/s and whirl velocity at inlet is 12 m/s. If power developed is 100 kW then discharge is
- (a)
0.73 m3/s
- (b)
0.57 m3/s
- (c)
0.91 m3/s
- (d)
0.83 m3/s
Velocity at entrance and exit of a conical draft tube are 6 m/s and 1.3 m/s respectively. Tail water is 5 m below the entrance of draft tube. Assuming friction loss of 0.1 m, atmospheric pressure head as 10.3 m of water. Pressure head at entrance to draft tube
- (a)
4.27 m
- (b)
1.29 m
- (c)
3.65 m
- (d)
2.87 m
A reaction turbine with draft tube is shown in figure. Net head available is
- (a)
H
- (b)
H- Hs
- (c)
Hs
- (d)
-Hs
The given figure belongs to centrifugal pump. Impeller is rotating anticlockwise and velocity diagram at outlet is shown. The vane is
- (a)
backward
- (b)
radial
- (c)
forward
- (d)
Cannot be determined
A centrifugal pump has speed 300 rpm, it consumes 17 kW power. It produces 30 m manometric head and delivers 1 m3/s discharge, then its specific speed is
- (a)
26.27
- (b)
29.21
- (c)
31.02
- (d)
23.41
A pump delivers a discharge to head of 30 m. Given, suction lift = 5.58 m, atmospheric head = 9.786, friction loss in inlet pipe = 0.3 rn, If vapour pressure is 3.0 kPa (absolute) then minimum value of NPSH is
- (a)
4.2 m
- (b)
3.6 m
- (c)
1.2 m
- (d)
7.1 m
For a centrifugal pump, Thoma's cavitation factor is 0.12 and manometric head is 30 rn, then NPSH is
- (a)
2.1
- (b)
3.6
- (c)
4.2
- (d)
3.1