WorksheetsNozzle
Total questions: 15
Worksheet time: 17mins
A nozzle is said to be a convergent nozzle
A.when the cross-section of the nozzle increases continuously from entrance to exit
B.when the cross-section of the nozzle decreases continuously from entrance to exit
C.when the cross-section of the nozzle first decreases from entrance to throat and then increases from its throat to exit
D.none of the above
The flow through a nozzle is regarded as
A.constant volume flow
B.constant pressure flow
C.isothermal flow
D.isentropic flow
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
The pressure at which the steam leaves the nozzle is known as back pressure
A.Correct
B.Incorrect
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
The rate of discharge through the nozzle __________ when the exit pressure is gradually reduced.
A.remains same
B.decreases
C.increases
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 square root K
B.V = 44.72 K hd
C.V = 44.72 K square root hd
D.V = 44.72 K hd
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
The critical pressure ratio for initially wet steam is
A.0.546
B.0.577
C.0.582
D.0.601
A steam nozzle is a passage of varying cross section through which the kinetic energy of steam is converted into heat energy
a) True
b) False
Calculate the enthalpy drop steam enters a convergent-divergent nozzle at 11 bar and 250°C and leaves at 1 bar. The expansion is to be considered metastable.
a) 427031.34 kJ/kg
b) 55648.32 kJ/kg
c) 323654.25 kJ/kg
d) 158469.21 kJ/kg
What is the value of index of expansion for supersaturated steam. (Pvn=C, n is the index of expansion)
a) 1.300
b) 1.013
c) 1.135
d) 1.000
Determine the velocity coefficient if the efficiency of a convergent-divergent steam nozzle is 92%. The inlet velocity of steam is negligible.
a) 0.959
b) 0.120
c) 0.465
d) 0.542
Initial velocity of the steam entering a convergent-divergent steam nozzle is 60 m/s. Steam expands from 15 bar and 250°C to 1 bar. Determine the exit velocity of steam if nozzle has an efficiency of 95%.
a) 973.08 m/s
b) 654.32 m/s
c) 785.45 m/s
d) 900.75 m/s
Dry and saturated steam at 10 bar enters a convergent-divergent nozzle and leaves at 1 bar. If 8% of heat drop is lost in friction find the percentage decrease in final velocity. Neglect initial velocity.
a) 5.65%
b) 3.87%
c) 2.14%
d) 4.08%
