Aerospace Engineering Gate 2012 Questions with Answer

Ques 14 GATE 2012


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

A

0.0018

B

0.018

C

0.18

D

1.18


(b) is the correct answer.

Ques 15 GATE 2012


A solid propellant of density 1800 kg/m3 has a burning rate law r=6.65 x 10-3p0.45mm/s, where p is pressure in Pascals. It is used in a rocket motor with a tubular grain with an initial burning area of 0.314 m2. The characteristic velocity is 1450 m/s. What should be the nozzle throat diameter to achieve an equilibrium chamber pressure of 50 bar at the end of the ignition transient?

A

35 mm

B

38 mm

C

41 mm

D

45 mm


(b) is the correct answer.

Ques 16 GATE 2012


A bipropellant liquid rocket motor operates at a chamber pressure of 40 bar with a nozzle throat diameter of 50 mm. The characteristic velocity is 1540 m/s. If the fuel-oxidizer ratio of the propellant is 1.8, and the fuel density is 900 kg/m3, what should be the minimum fuel tank volume for a burn time of 8 minutes

A

1.65 m3

B

1.75 m3

C

1.85 m3

D

1.95 m3


(b) is the correct answer.

Ques 17 GATE 2012


A thin long circular pipe of 10 mm diameter has porous walls and spins at 60 rpm about its own axis. Fluid is pumped out of the pipe such that it emerges radially relative to the pipe surface at a velocity of 1 m/s. [Neglect the effect of gravity.]
The maximum shear stress in N/m2 for the pipe is


(1.85 to 1.95) is the correct answer.

Ques 18 GATE 2012


A thin long circular pipe of 10 mm diameter has porous walls and spins at 60 rpm about its own axis. Fluid is pumped out of the pipe such that it emerges radially relative to the pipe surface at a velocity of 1 m/s. [Neglect the effect of gravity.]
The percentage change in the maximum shear stress, if diameter is doubled, while keeping thickness constant, is

A

-50

B

-25

C

-12.5

D

-6.25


(c) is the correct answer.

Ques 19 GATE 2012


In a semi-monocoque construction of an aircraft wing, the skin and spar webs are the primary carriers of

A

shear stresses due to an aerodynamic moment component alone.

B

normal (bending) stresses due to aerodynamic forces.

C

shear stresses due to aerodynamic forces alone.

D

shear stresses due to aerodynamic forces and a moment component.


(d) is the correct answer.

Ques 20 GATE 2012


The logarithmic decrement measured for a viscously damped single degree of freedom system is 0.125. The value of the damping factor in % is closest to

A

0.5

B

1.0

C

1.5

D

2.0


(b) is the correct answer.

Ques 21 GATE 2012


The mode shapes of an un-damped two degrees of freedom system are {1 0.5}T and {1 -0.675}T The corresponding natural frequencies are 0.45 Hz and 1.2471 Hz. The maximum amplitude (in mm) of vibration of the first degree of freedom due to an initial displacement of {2 1}T (in mm) and zero initial velocities is


(0.008 to 0.012) is the correct answer.

Ques 22 GATE 2012


The Airy stress function, φ=αx2+βxy+γy2 for a thin square panel of size l×l automatically satisfies compatibility. If the panel is subjected to uniform tensile stress, σo on all four edges, the traction boundary conditions are satisfied by

A

α=σo/2 β=0; γ=σo/2

B

α=σo; β=0; γ=σo.

C

α=0; β=σo/4; γ=0.

D

α=0; β=σo/2; γ=0.


(d) is the correct answer.

Ques 23 GATE 2012


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

A

1/2

B

2

C

1/√2

D

√2


(a) is the correct answer.

Ques 24 GATE 2012


A spring-mass system is viscously damped with a viscous damping constant c. The energy dissipated per cycle when the system is undergoing a harmonic vibration X Cos ωdt is given by

A

πcωdX2

B

πωdX2

C

πcωdX

D

πcωd2X


(a) is the correct answer.

Ques 25 GATE 2012


Buckling of the fuselage skin can be delayed by

A

increasing internal pressure.

B

placing stiffeners farther apart.

C

reducing skin thickness.

D

placing stiffeners farther and decreasing internal pressure.


(a) is the correct answer.

Ques 26 GATE 2012


The governing equation for the static transverse deflection of a beam under an uniformly distributed load, according to Euler-Bernoulli (engineering) beam theory, is a

A

2nd order linear homogenous partial differential equation.

B

4th order linear non-homogenous ordinary differential equation.

C

2nd order linear non-homogenous ordinary differential equation.

D

4th order nonlinear homogenous ordinary differential equation.


(b) is the correct answer.

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