steam nozzles and turbines




2).
A turbine is said to have an axial discharge when the steam leaves the blade tip at __________ to the direction of the blade motion.
A   60°   
B   90°   
C   180°   
D   270°   
ANS: B - 90°

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3).
The flow through a nozzle is regarded as
A   constant volume flow   
B   constant pressure flow   
C   isothermal flow   
D   isentropic flow   
ANS: D - isentropic flow

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4).
The ratio of total useful heat drop to the total isentropic heat drop, is called
A   stage efficiency   
B   internal efficiency   
C   Rankine efficiency   
D   none of these   
ANS: B - internal efficiency

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5).
The pressure at which the steam leaves the nozzle is known as back pressure.
A   Correct   
B   Incorrect   
ANS: A - Correct

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6).
The discharge of steam in a convergent-divergent nozzle __________ after the throat (i.e. in the divergent portion of the nozzle)
A   remains constant   
B   decreases   
C   increases   
ANS: A - remains constant

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7).
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
A   remains same   
B   decreases   
C   increases   
ANS: C - increases

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8).
The velocity of steam leaving the nozzle (V) is given by (where K = Nozzle coefficient or nozzle efficiency, and hd = Enthalpy or heat drop during expansion of steam in a nozzle)
A   V = 44.72 hd √K   
B   V = 44.72 K √hd   
C   V = 44.72 √K hd   
D   V = 44.72 K hd   
ANS: B - V = 44.72 K √hd

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9).
In a nozzle, whole frictional loss is assumed to occur between
A   inlet and thoroat   
B   inlet and outlet   
C   throat and exit   
D   all of these   
ANS: C - throat and exit

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10).
The critical pressure ratio for initially wet steam is
A   0.546   
B   0.577   
C   0.582   
D   0.601   
ANS: C - 0.582

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