GATE Aerospace engineering online test paper 6

Question 1 of 15

1. Question

In a closed-circuit supersonic wind tunnel, the convergent-divergent (C-D) nozzle and test section are followed by a C-D diffuser to swallow the starting shock. Here, we should have the

diffuser throat larger than the nozzle throat and the shock located just at the diffuser throat.
"diffuser throat larger than the nozzle throat and the shock located downstream of the diffuser throat."
"diffuser throat of the same size as the nozzle throat and the shock located just at the diffuser throat."
"diffuser throat of the same size as the nozzle throat and the shock located downstream of the diffuser throat"

Question 2 of 15

2. Question

A vortex flowmeter works on the principle that the Strouhal number of 0.2 is a constant over a wide range of flow rates. If the bluff-body diameter in the flowmeter is 20 mm and the piezo-electric transducer registers the vortex shedding frequency to be 10 Hz, then the velocity of the flow would be measured as

.1m/s
1m/s
10m/s
100m/s

Question 3 of 15

3. Question

The stagnation temperatures at the inlet and exit of a combustion chamber are 600 K and 1200 K, respectively. If the heating value of the fuel is 44 MJ/kg and specific heat at constant pressure for air and hot gases are 1.005 kJ/kg.K and 1.147 kJ/kg.K respectively, the fuel-to-air ratio is

0.0018
0.018
0.18
1.18

Question 4 of 15

4. Question

The propellant in a single stage sounding rocket occupies 60% of its initial mass. If all of it is expended instantaneously at an equivalent exhaust velocity of 3000 m/s, what would be the altitude attained by the payload when launched vertically? [Neglect drag and assume acceleration due to gravity to be constant at 9.81 m/s2.]

315km
335km
365km
385km

Question 5 of 15

5. Question

The boundary condition of a rod under longitudinal vibration is changed from fixed-fixed to fixedfree. The fundamental natural frequency of the rod is now k times the original frequency, where k is

0.5
2
1/(square root of 2)
square root of 2

Question 6 of 15

6. Question

Buckling of the fuselage skin can be delayed by

increasing internal pressure.
placing stiffeners farther apart
reducing skin thickness
placing stiffeners farther and decreasing internal pressure.

Question 7 of 15

7. Question

With increase in airfoil thickness, the critical Mach number for an airfoil is likely to

decrease
increase
remains unchanged
be undefined

Question 8 of 15

8. Question

Due to a body in potential flow, the velocity at a point A in the flow field is 20 m/s while the free stream velocity is only 10 m/s. The value of coefficient of pressure (Cp) at the point A is

0
-3.0 : -3.0
3:03
4:04

Question 9 of 15

9. Question

Which of the following airfoil will have location of the maximum camber at half chord length from the leading edge?

NACA 5212
NACA 1225
NACA 2215
NACA 2512

Question 10 of 15

10. Question

Which of the following statement is NOT TRUE across an oblique shock wave?

Static temperature increases, total temperature remains constant.
Static pressure increases, static temperature increases.
Static temperature increases, total pressure decreases
Static pressure increases, total temperature decreases.

Question 11 of 15

11. Question

For a completely subsonic isentropic flow through a convergent nozzle, which of the following statement is TRUE?

Pressure at the nozzle exit > back pressure.
Pressure at the nozzle exit < back pressure
Pressure at the nozzle exit = back pressure
Pressure at the nozzle exit = total pressure

Question 12 of 15

12. Question

Which of the following aircraft engines has the highest propulsive efficiency at a cruising Mach number of less than 0.5?

Turbofan engine
Turbojet engine
Turboprop engine
Ramjet engine

Question 13 of 15

13. Question

Air, with a Prandtl number of 0.7, flows over a flat plate at a high Reynolds number. Which of the following statement is TRUE?

Thermal boundary layer is thicker than the velocity boundary layer.
Thermal boundary layer is thinner than the velocity boundary layer
Thermal boundary layer is as thick as the velocity boundary layer
There is no relationship between the thicknesses of thermal and velocity boundary layers.

Question 14 of 15

14. Question

The total number of material constants that are necessary and sufficient to describe the three dimensional Hooke’s law for an isotropic material is

2.0 : 2.0
2.0 : 3.0
2.0 : 2.5
none of these

Question 15 of 15

15. Question

Determine the correctness or otherwise of the following statements, [a] and [r]:
[a]: In a plane stress problem, the shear strains along the thickness direction of a body are zero but the normal strain along the thickness is not zero.
[r]: In a plane stress problem, Poisson effect induces the normal strain along the thickness direction of the body

Both [a] and [r] are true and [r] is the correct reason for [a].
Both [a] and [r] are true but [r] is not the correct reason for [a]
Both [a] and [r] are false.
[a] is true but [r] is false

Pos.	Name	Entered on	Points	Result
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