# MULTIPLE CHOICE QUESTION (MCQ) ANSWERS ON NOZZLES

MULTIPLE CHOICE QUESTION (MCQ) ANSWERS ON NOZZLES

1.  The critical pressure ratio for initially dry saturated steam across a steam nozzle is

(a) 0.582

(b) 0.546

(c) 0.578

(d) none

Ans: (c)

1. The critical pressure ratio for initially wet steam across a steam nozzle is

(a) 0.582

(b) 0. 546

(c) 0.578

(d) None

Ans: (a)

3. The critical pressure ratio for initially super-heated steam across a steam nozzle is

(a) 0.582

(b) 0.546

(c) 0.578

(d) None

Ans: (b)

4. The efficiency of the nozzle is

(a) Iso-thermal enthalpy drop/Isen-tropic enthalpy drop

(b) Isobaric enthalpy drop/Isen-tropic enthalpy drop

(c) Actual enthalpy drop/Isen-tropic enthalpy drop

(d) None

Ans: (c)

5. Velocity coefficient in a steam nozzle is

(a) (Isothermal enthalpy drop/Isentropic enthalpy drop)0.5

(b) (Actual enthalpy drop/Isentropic enthalpy drop)0.5

(c) (Isobaric enthalpy drop/Isentropic enthalpy drop)0.5

(d) None

Ans: (b)

6. Theoretical velocity at the exit of the nozzle will be

(a) c2 = 44.42 (h1-h2)0.5

(b) c2 = 44.92 (h1-h2)0.5

(c )  c2 = 44.72 (h1-h2)0.5

(d) None

Ans: (c )

7. The critical pressure ratio in a steam nozzle is equal to

(a) [(γ+1)/2](γ/(γ+1))

(b) [(2/(γ+1)] (γ/(γ+1))
(c)
[(2/(γ+1)] ((γ+1)/γ)

(d) None

Ans: (b)

8. The equation for the shape of a nozzle is

(a) dA/A =(dc/c)[M2 –1)

(b) dA/A =(dc/c)[1–M2)

(c) dA/A =(dc/c)[M2 +1)

(d) None

Ans: (a)

9. Critical velocity in a nozzle is given by the relation

(a) C* =(γRT*)5

(b) C* =(RT*/γ)5

(c) C* =(γR/T*)5

(d) None

Ans: (a)

10. When M = 1 the velocity in a nozzle be

(a) Minimum

(b) Maximum

(c) Neither minimum nor maximum

(d) None

Ans: (b)

11. When M = 1 the area of the nozzle be

(a) Minimum

(b) Maximum

(c) Neither minimum nor maximum

(d) None

Ans: (a)

12. Using equation dA/A =(dc/c)[M2 –1) for a nozzle, when M<1 , velocity in the nozzle will increase if the area of the nozzle

(a) Decreases

(b) Increases

(c) Constant

(d) None

Ans:(a)

13. Using equation dA/A =(dc/c)[M2 –1) for a nozzle, when M<1 , velocity in the nozzle will decrease if the area of the nozzle

(a) Decreases

(b) Increases

(c) Constant

(d) None

Ans:(b)

14. Using equation dA/A =(dc/c)[M2 –1) for a nozzle, when M>1 , velocity in the nozzle will increase if the area of the nozzle

(a) Decreases

(b) Increases

(c) Constant

(d) None

Ans:(b)

15. Using equation dA/A =(dc/c)[M2 –1) for a nozzle, when M>1 , velocity in the nozzle will decrease if the area of the nozzle

(a) Decreases

(b) Increases

(c) Constant

(d) None

Ans:(a)

16. Stagnation properties are used when the value of M is

(a) <0.1

(b) <0.4

(c) >0.4

(d) None

17. Efficiency of a nozzle vs efficiency of a diffuser is

(a) Less

(b) Equal

(c) More

(d) None

18. A nozzle is said to be choking under

(a) Minimum flow rate

(b) Maximum flow rate

(c) Neither maximum nor minimum flow rate

(d) None

Ans: (b)

19. Velocity of steam in the divergent portion of the nozzle

(a) Decreases

(b) Increases

(c) Remains constant

(d) None

Ans: (b)

20. There is more friction in the

(a) Convergent portion

(b) Divergent portion

(c) At the throat

(d) None

Ans: (b)

21. A steam nozzle is said to be choked if

(a) Steam flow through the nozzle decreases

(b) Pressure at throat is less than the exit pressure

(c) Pressure at throat is equal to the steam supply pressure

(d) None

Ans: (d)

22. Shock effect in a nozzle generally occurs in the

(a) Convergent portion

(b) At the exit

(c) Divergent portion

(d) None

23. Which type of nozzle is used in a steam turbine

(a) Convergent

(b) Divergent

(c) Convergent-divergent

(d) None