6. A normal shock-
A. causes disruption and reversal of flow pattern
B. may occur only in a diverging passage
C. is more service than an oblique shock
D. moves with a velocity equal to the sonic velocity
7. Employing superheated steam in turbines leads to-
A. Increase in the erosion of blading
B. A decrease in the erosion of blading
C. No erosion in blading
D. No change in the erosion of blading
8. In a reaction turbine stage enthalpy drop in the stator blades is 4.62 Kj/Kg and that in the rotor blades is 2.38 Kj/Kg. The degree of reaction of the stage is-
A. 0.55
B. 0.43
C. 0.34
D. 0.29
9. An emergency of a steam turbine trips the turbine when-
- shafts exceed 100 % of its rated speed
- condenser becomes hot due to inadequate cooling water circulation
- lubrication system fails
- balancing of the turbine is not proper
A. 1, 2 & 3
B. 2 & 4
C. 2, 3 & 4
D. All the above
10. The absolute jet exit velocity from a jet engine is 2800 m/s and the forward flight velocity is 1400 m/s. Find the propulsive efficiency is-
A. 55.52%
B. 66.67%
C. 75.25%
D. 80%