This set of Thermodynamics Multiple Choice Questions & Answers (MCQs) focuses on “One Dimensional Steady Isentropic Flow and Choking-1 “.
1. Which of the following produce continuous change in state of a flowing stream?
a) wall friction
b) changes in cross-sectional area
c) energy effects
d) all of the mentioned
View Answer
Explanation: These are three most common factors.
2. What does a nozzle do?
a) decreases KE at the expense of pressure
b) increases KE at the expense of pressure
c) decreases PE at the expense of velocity
d) increases PE at the expense of velocity
View Answer
Explanation: A nozzle is a simple duct which increases KE of fluid at the expense of pressure of the fluid.
3. What does a diffuser do?
a) decreases KE and gains pressure
b) increases KE and loses pressure
c) decreases PE and gains velocity
d) increases PE and loses velocity
View Answer
Explanation: A diffuser is a passage through which KE of fluid decreases and gains pressure.
4. The same passage or duct can be either a diffuser or a nozzle.
a) true
b) false
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Explanation: This depends on the end conditions across it.
5. The ____ section of a nozzle or diffuser is called throat.
a) constant area
b) maximum
c) minimum
d) all of the mentioned
View Answer
Explanation: The minimum section is called throat.
6. In adiabatic flow, what remains constant?
a) stagnation temperature
b) stagnation enthalpy
c) both of the mentioned
d) none of the mentioned
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Explanation: Both of these does not change on adiabatic flow.
7. As pressure decreases, velocity also decreases.
a) true
b) false
View Answer
Explanation: As pressure decreases, velocity increases.
8. When Mach number, M<1 and flow area decreases, then
a) pressure decreases
b) velocity increases
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is the case when inlet velocity is subsonic and flow area decreases.
9. When Mach number, M<1 and flow area increases, then
a) pressure increases
b) velocity decreases
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is the case when inlet velocity is subsonic and flow area increases.
10. For a subsonic flow,
a) a convergent passage becomes diffuser and a divergent passage becomes nozzle
b) a divergent passage becomes diffuser and a convergent passage becomes nozzle
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is true when flow is subsonic.
11. When Mach number, M>1 and flow area decreases, then
a) pressure increases
b) velocity decreases
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is the case when inlet velocity is supersonic and flow area decreases.
12. When Mach number, M>1 and flow area increases, then
a) pressure decreases
b) velocity increases
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is the case when inlet velocity is supersonic and flow area increases.
13. For a supersonic flow,
a) a convergent passage becomes diffuser and a divergent passage becomes nozzle
b) a divergent passage becomes diffuser and a convergent passage becomes nozzle
c) both of the mentioned
d) none of the mentioned
View Answer
Explanation: This is true when flow is supersonic.
Sanfoundry Global Education & Learning Series – Thermodynamics.
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