Aerospace Engineering GATE 2014 Questions with Answer

Ques 1 Aerodynamics

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For a NACA 5-digit airfoil of chord c, the designed lift coefficient and location of maximum camber along the chord from the leading edge are denoted by C_L and X_m respectively. For NACA12018 airfoil, which combination of C_L and X_m given below are correct?

A

C_L=0.12 and X_m=0.1c

B

C_L=0.12 and X_m=0.2c

C

C_L=0.15 and X_m=0.18c

D

C_L=0.15 and X_m=0.2c

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Ques 2 Aerodynamics

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For inviscid, supersonic flow over a diamond shaped airfoil, shown in the figure, which statement is the following?

A

The airfoil will experience zero lift and positive drag force

B

The airfoil will experience positive lift and zero drag force

C

The airfoil will experience negative lift and zero drag force

D

The airfoil will experience positive lift and positive drag force

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Ques 3 Aerodynamics

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Consider supersonic flow near a corner (at an angle θ from the horizontal) with an attached oblique shock (at an angle β with horizontal) as shown in figure. If Mach number M decreases gradually from a high supersonic value, which of the following statements is correct?

A

will decrease if the shock is a weak shock

B

will decrease if the shock is a strong shock

C

B will increase for both weak and strong shocks

D

remains unchanged for both weak and strong shocks

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Ques 4 Aerodynamics

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The streamlines of a potential line vortex is concentric circles with respect to the vortex center as shown in figure. Velocity along these streamlines, outside the core of the vortex can be written as, v_θ=Γ/(2πr), where strength of the vortex is Γ/(2π) and r is radial direction. The value of circulation along the curve shown in the figure is:

A

Γ

B

-2Γ

C

2Γ

D

0

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Ques 5 Aerodynamics

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To observe unsteady separated flow in a diverging channel, bubbles are injected at each 10ms interval at point A as shown in figure. These bubblesact as tracer particles and follow the flow faithfully. The curved line AB shown at any instant represents:

A

Streamline, streakline and pathline

B

Streamline and pathline

C

Only a pathline

D

Only a streakline

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Ques 6 Aerodynamics

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For a steady, incompressible two-dimensional flow, represented in Cartesian co-ordinates (x, y), a student correctly writes the equation of pathline of any arbitrary particle as,dx/dt=ax and dy/dt=by, where a and b are constants having unit of (second)^-1 If value of a is 5, the value of b is

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Ques 7 Aerodynamics

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Figures (a) - (d) below show four objects. Dimensions and surface conditions of the objects are shown in the respective figures. All four objects are placed independently in a steady, uniform flow of same velocity and the direction of flow is from left to right as shown in (a). The flow field can be considered as 2-D, viscous and incompressible. Following statements are made regarding the drag that these objects experience.

(i) Drag of object (a) is more than the drag of object (d)
(ii) Drag of object (a) is less than the drag of object (d)
(iii) Drag of object (b) is more than the drag of object (c)
(iv) Drag of object (c) is more than the drag of object (b)
(v) Drag of object (a) is more than the drag of object (b)

Choose the correct combination of statements from the options given above:

A

(i), (iii), (v)

B

(ii), (iv), (v)

C

(i), (iii)

D

(iv), (v)

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Ques 8 Aerodynamics

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A student needs to find velocity across a stationary normal shock. He measures density and pressure across the shock as shown in the figure below. 1bar=10⁵Pa. (No shock table is needed for the calculations). The value of u₁ in m/s is

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Ques 9 Aerodynamics

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For inviscid, compressible flow past a thin airfoil, shown in the figure, free-stream Mach number . Ratio of pressure at point A and p_∞ 0.8 and specific heat ratio is 1.4, If the Mach number at point A is 1.0 and rest of the flow field is subsonic, the value of M_∞ is

A

2.95

B

0.79

C

1.18

D

0.64

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Ques 10 Aerodynamics

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A student can measure free-stream velocity of a low-speed wind tunnel using a
i. Pitot tube alone aligned with the flow direction.
ii. Pitot tube aligned with the flow direction with static pressure measurement at an appropriate position on the tunnel wall.
iii. Pitot tube aligned with the flow direction along with barometer pressure reading of the outside ambient.
iv. Pitot static tube alone aligned with the flow direction.

Considering the above statements, which of the following options is correct?

A

(i) only

B

(i) & (ii)

C

(ii) & (iv)

D

(i), (iii) & (iv)

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Ques 11 Aerodynamics

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Induced velocity w at a point z=z₁ along the lifting line can be calculated using the formula
w(z₁)=-(1/(4π))∫_-s^s(dΓ/dz)(1/(z-z₁))dz.
Given Γ²/Γ_o²+z²/s²=1, wherez, Γ_o and sare given in figure below. For theabove semi-elliptic distribution of circulation, , the downwash velocity at any point , for symmetric flight can be obtained as, where
w(z₁)=(Γ_o/(4πs))[π+z₁I], I=z₁∫_-s^S(dz/(√(s²-z²)(z-z₁))).
Which of the following options is correct if the induced drag is D_i (given ∫(1-z²/s²)dz=πs/2))

A

I=0 and D_i=(8ρΓ_o²)/π

B

I=I and D_i=(8ρΓ_o²)/π

C

I=0 and D_i=(πρΓ_o²)/8

D

I=I and D_i=(πρΓ_o²)/8

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Ques 12 Aerodynamics

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Two overflowing water reservoirs are connected with a100m long pipe of circular cross-section (of radius, R=0.02m), such that height difference h remains constant as shown in the figure below. The centerline velocity in the pipe is 10m/s. The velocity profile inside the pipe over the entire length is
u=-(R²/(4μ))dp/dx[1-r²/R²],
where, dp/dx is a constant pressure gradient along the pipe length, x is measured from theleft end of the pipe along its central axis and r is radial location inside the pipe with respect to its axis.(Given data: Density and kinematic viscosity of water are 1000kg/m^s and 1×10^-6m²/s respectively; acceleration due to gravity is 10m/s²). If all other losses except the frictional losses at the pipe wall are neglected, the value of h in meter is

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Ques 13 Aerospace Propulsion

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Match the appropriate engine (in right column) with the corresponding aircraft (in left column) for most efficient performance of the engine.

a. Low speed transport aircraft
b. High subsonic civilian aircraft
c. Supersonic fighter aircraft
d. Hypersonic aircraft

i. Ramjet
ii. Turboprop
iii. Turbojet
iv. Turbofan

A

a-iv, biii, c-i d-ii

B

a-ii, bi, c-iii d- iv

C

a-i hii, civ, d- iii

D

a-ii, h-iv, c-iii, d-i

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