Quasi-One-Dimensional Flow topics include: Governing equations, area velocity relations, nozzles, quasi one dimensional flow diffusers and wave reflection. Quasi-one-dimensional flow is a type of flow where all variables change primarily along one direction. The cross-sectional area of the stream tubes can vary along the same direction as the flow. For the equations to be valid, the variation in cross-sectional area must be smooth.  In a quasi-one-dimensional flow, the cross-section is allowed to vary smoothly, but flow quantities vary in one direction only. The main difference between 1D... Show more

Quasi-One-Dimensional Flow topics include: Governing equations, area velocity relations, nozzles, quasi one dimensional flow diffusers and wave reflection.

Quasi-one-dimensional flow is a type of flow where all variables change primarily along one direction. The cross-sectional area of the stream tubes can vary along the same direction as the flow. For the equations to be valid, the variation in cross-sectional area must be smooth. 

In a quasi-one-dimensional flow, the cross-section is allowed to vary smoothly, but flow quantities vary in one direction only. The main difference between 1D and quasi-1D flows is the cross-sectional area of the passage. For quasi-1D flows, it is no longer constant, but is a function of the location. 

A flow in a duct with slowly-varying area is an example of a quasi-one-dimensional flow. In practice, this means that the slope of the duct walls is small. 

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Aerodynamics Practice Test: Quasi-One-Dimensional Flow

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25 Questions

1. Which is the Euler’s equation for the quasi – one dimensional flow?

dp = -ρududp = ρududp = –\(\frac {u}{ρ}\)dudp = \(\frac {ρ}{u}\)du

2. Oblique shock diffuser has a better pressure recovery than a normal shock diffuser.

MaybeTrueFalseDon't know

3. Which of this conditions is necessary to achieve flow in a nozzle?

\(\frac {P_e}{P_0}\) = 1\(\frac {P_e}{P_0}\) = 0\(\frac {P_e}{P_0}\) < 1\(\frac {P_e}{P_0}\) > 1

4. What happens in case of a choked flow?

Normal shock is created at the inlet of the nozzleWhen flow is sonic and mass flow remains constant at the throat despite reducing exit pressureWhen flow becomes supersonic at the throatWhen the exit pressure is reduced to a point where the flow becomes subsonic at throat

5. According to the energy equation, which of these properties remain constant along the flow?

Potential energyTotal enthalpyKinetic energyTotal entropy

6. If the given conditions for a nozzle are P₀₁ = 1 atm, P_e = 0.3143 atm, then what is the ratio of exit area to throat area?

1.251.51.1151.15

7. What is the diffuser efficiency of a normal shock diffuser?

\(\frac {1}{2}\) Inifinty01

8. What is the differential form of momentum equation for the quasi one – dimensional flow known as?

Froude equationKelvin’s equationEuler’s equationBernoulli’s equation

9. Why can’t build an ideal supersonic diffuser with no total pressure losses?

Varying cross – sectional areaVarying throat areaPresence of shock wavesChoked flow

10. For which of these flows do we need a divergent duct to increase the velocity of the flow?

Supersonic flowHypersonic flowSonic flowSubsonic flow

11. Sonic flow exists at the throat of an equilibrium chemically reacting nozzle flow?

FalseMaybeDon't knowTrue

12. Total pressure loss in a normal shock diffuser is less than the oblique shock diffuser.

MaybeTrueDon't knowFalse

13. What is the value of surface integral between surface 1 and 2 of the control volume while finding the continuity equation?

V2.dSZeroV.dSdS

14. What is the differential form of energy equation for quasi one – dimensional flow?

dh + u2du = 0dh – udu = 0dh + udu = 0dh – u2du = 0

15. What is the exit Mach number if the convergent nozzle is choked?

0.501.51

16. What happens to the velocity of the supersonic flow in the convergent duct?

DecreasesChanges periodicallyIncreasesRemains the same

17. For a subsonic flow, what should be the value of dA to get flow acceleration?

OnePositiveNegativeZero

18. Which of these properties remain constant in the ideal isentropic supersonic diffuser?

VelocityTotal pressureMass flowMach number

19. For a nozzle with the following data \(\frac {A_e}{A_t}\) = 1.616, P₀₁ = 1 atm, P_e = 0.947 atm, what is the Mach number at the throat of the nozzle?

0.500.250.750.58

20. For a flow in a duct, what is Mach number a function of?

Local duct area to sonic throat areaSonic throat area to local duct areaLocal duct area to convergent duct areaLocal duct area to divergent duct area

21. The area – Mach number relation yields how many solution(s) for a given Mach number?

2013

22. What is the role of the diffuser?

Decrease the flow velocity after test sectionDecrease the flow velocity inside the test sectionIncrease the flow velocity inside test sectionIncrease the flow velocity after test section

23. In the area – Mach relation A < A^* or A ≥ A^*.

FalseTrueDon't knowMaybe

24. What happens to the mass flow rate if the reservoir pressure is doubled?

Becomes halfRemains sameBecomes one – fourthDoubled

25. Which of these conditions result in underexpanded nozzle?

Pe > PaPe << PaPe = PaPe < Pa