Unit 3: Expansion waves and flow over nozzles - Practice Quiz

1 A Prandtl-Meyer expansion occurs when a supersonic flow turns around what type of corner?

2 What happens to the Mach number as a supersonic flow passes through a Prandtl-Meyer expansion?

3 How does static pressure change across a Prandtl-Meyer expansion?

4 For a calorically perfect gas, an ideal Prandtl-Meyer expansion is treated as which type of process?

5 If a supersonic flow turns through an expansion angle , which relation connects the upstream and downstream Mach numbers?

6 A nozzle is under-expanded when its exit pressure has what relation to ambient pressure ?

7 Which waves commonly form just outside an under-expanded nozzle exit?

8 A nozzle is over-expanded when its exit pressure has what relation to ambient pressure ?

9 Which flow feature initially adjusts an over-expanded jet toward the higher ambient pressure?

10 A convergent-divergent nozzle operates at its design condition when which pressure relation holds?

11 The maximum expansion turning angle for a given upstream Mach number is limited by what quantity?

12 For an upstream Mach number , the maximum possible expansion angle is given by which expression?

13 As the Mach number approaches infinity, the Prandtl-Meyer function approaches what behavior?

14 For a perfect gas, the limiting Prandtl-Meyer angle depends primarily on which property?

15 What downstream Mach-number limit corresponds theoretically to the maximum Prandtl-Meyer expansion?

16 In a simple-wave region, how many characteristic families carry a constant Riemann invariant throughout the region?

17 A centered Prandtl-Meyer expansion fan is a common example of what type of region?

18 In a non-simple region, the flow is generally influenced by which characteristic families?

19 Which method is commonly used to analyze two-dimensional supersonic simple and non-simple regions?

20 What is the usual result when characteristic waves from opposite families interact?

21 Air with and upstream Mach number turns through a Prandtl-Meyer expansion. Given , what is the approximate downstream Mach number?

22 An isentropic expansion accelerates air from to . Using , determine the approximate static-pressure ratio .

23 Which combination of property changes occurs across an ideal Prandtl-Meyer expansion fan?

24 For air, and . Through what angle must a uniform flow at expand to reach ?

25 A Mach air stream passes around a convex corner that turns the flow by . Given and , estimate the downstream Mach number.

26 A converging-diverging nozzle has an exit pressure of while discharging into an ambient pressure of . How is the jet classified?

27 What wave pattern initially forms at the lip of an under-expanded supersonic nozzle?

28 A nozzle operates with and . Which behavior is expected just outside its exit?

29 A nozzle is initially perfectly expanded. Its chamber conditions and geometry remain fixed, but the ambient pressure is reduced. Assuming the exit state inside the nozzle remains unchanged, what is the new operating condition?

30 Which adverse effect is most likely when a converging-diverging nozzle operates in a strongly over-expanded condition?

31 For a calorically perfect gas, which expression gives the limiting Prandtl-Meyer angle as ?

32 For air, . What is the maximum additional isentropic turning possible for a flow initially at , where ?

33 Air at has . Using , determine its maximum possible additional Prandtl-Meyer turning angle.

34 Can an attached isentropic expansion turn a Mach air stream through if its maximum additional turning angle is ?

35 How does decreasing the specific-heat ratio affect the limiting Prandtl-Meyer angle ?

36 What distinguishes a simple-wave region in two-dimensional, steady, irrotational supersonic flow?

37 How is the wave field immediately inside an ideal centered Prandtl-Meyer expansion fan classified?

38 Two expansion-wave systems from opposite walls intersect within a supersonic passage. How should their interaction region generally be classified?

39 Which information is generally needed to determine a point inside a non-simple supersonic region using the method of characteristics?

40 Within a simple Prandtl-Meyer expansion, the Prandtl-Meyer angle increases from to . What is the magnitude of the corresponding flow deflection?

41 Air with enters a centered Prandtl-Meyer expansion at and is turned through . Using , what is the downstream Mach number?

42 Air expands isentropically from to . What is the approximate static-pressure ratio ?

43 A uniform air stream at passes through two noninteracting, same-sense expansion corners of and . What is the final Mach number?

44 For the isentropic expansion from to in air, which pair correctly describes the temperature changes?

45 A supersonic air stream initially at undergoes an isentropic expansion with measured . What turning angle is most consistent with the measurement?

46 A converging-diverging air nozzle has an exit area ratio designed for . It operates with . Given that the isentropic design value is , how is the nozzle classified in an ideal inviscid analysis?

47 A nozzle delivers immediately upstream of a normal shock located exactly at its exit. For air, what back-pressure ratio approximately holds the shock at that location?

48 Which wave pattern is expected immediately downstream of a strongly under-expanded supersonic nozzle?

49 A choked converging-diverging nozzle contains a normal shock in its diverging section. As the back pressure is gradually reduced while geometry and reservoir conditions remain fixed, how does the shock generally change?

50 A choked nozzle has while the ambient condition is . Which statement correctly describes the exit adjustment and pressure-thrust term?

51 What is the limiting Prandtl-Meyer angle as for a calorically perfect gas?

52 For air with , a stream initially at has . Given , what is its maximum additional isentropic expansion turn?

53 For which value of is the limiting Prandtl-Meyer angle exactly ?

54 Air at is required to expand isentropically around a convex corner through . Since and , what does Prandtl-Meyer theory predict?

55 An air stream at , for which , first expands through . What is the greatest further Prandtl-Meyer turn theoretically available?

56 Define characteristics by and characteristics by . Which compatibility relations apply to steady, two-dimensional, isentropic, irrotational supersonic flow?

57 Which statement most accurately characterizes a centered Prandtl-Meyer expansion fan as a simple-wave region?

58 At a point in an isentropic characteristic net, the two incoming compatibility values are and . What are the local flow angle and Prandtl-Meyer angle?

59 In a smooth characteristic solution, two characteristics belonging to the same family are predicted to intersect. What is the correct physical interpretation?

60 Two finite expansion-wave systems of opposite characteristic families overlap without forming shocks. Which description best fits the overlap region?