low
very low
high
very high
✅ The correct answer is option D.
Steam Nozzles and Turbines MCQs
2. A nozzle is said to be a convergent-divergent nozzle, when the cross-section of a nozzle first decreases from its entrance to throat and then increases from its throat to exit.
TRUE
FALSE
✅ The correct answer is option A.
3. The nozzle efficiency is the ratio of
workdone on the blades to the energy supplied to the blades
workdone on the blades per kg of steam to the total energy supplied per stage per kg of steam
energy supplied to the blades per kg of steam to the total energy supplied per stage per kg of steam
none of the above
✅ The correct answer is option C.
4. The pressure velocity compounded impulse turbine allows a bigger pressure drop and hence __________ number of stages are required.
more
less
✅ The correct answer is option B.
5. The blade friction in the impulse turbine reduces the velocity of steam by __________ while it passes over the blades.
10 to 15%
15 to 20%
20 to 30%
30 to 40%
✅ The correct answer is option A.
6. For a Parson’s reaction turbine, if α1 and α2 are fixed blade angles at inlet and exit respectively and β1 and β2 are the moving blade angles at entrance and exit respectively, then
α1 = α2 and β1 = β2
α1 = β1 and α2 = β2
α1 < β1 and α2 > β2
α1 = β2 and β1 = α2
✅ The correct answer is option D.
7. The pressure of steam, in reaction turbines, is reduced in the fixed blades as well as in moving blades.
Correct
Incorrect
✅ The correct answer is option A.
8. De-Laval turbines are mostly used
where low speeds are required
for small power purposes and low speeds
for large power purposes
for small power purpos
✅ The correct answer is option D.
9. In a Parson’s turbine stage, blade velocity is 320 m/s at the mean radius and rotor blade exit angle is 30°. For minimum kinetic energy of the steam leaving the stage, the steam velocity at the exit of the rotor will be
160/3 m/s
320/3 m/s
640/3 m/s
640 m/s
✅ The correct answer is option C.
10. The compounding of turbines is done in order to
reduce speed of rotor
improve efficiency
reduce exit losses
all of these
✅ The correct answer is option D.