Aerospace Engineering Gate Yearwise 


Aerospace Engineering Gate 2009 Questions with Answer

Ques 40 GATE 2009

Air enters the combustor of a gas-turbine engine at a total temperature T0 of 500 K. The air stream is split into two parts: primary and secondary streams. The primary stream reacts with fuel supplied at a fuel-air ratio of 0.05. The resulting combustion products are then mixed with the secondary air stream to obtain gas with total temperature of 1550 K at the turbine inlet. The fuel has a heating value of 42 MJ/kg. The specific heats of air and combustion products are taken as cp = 1 kJ/kg/K.
The approximate ratio of mass flow rates of the primary air stream to the secondary air stream required
to achieve the turbine inlet total temperature of 1550 K is

A

2:1

B

1:2

C

1:1.5

D

1:1


(b) is the correct answer.

Ques 41 GATE 2009

Classify the following propellants as: cryogenic (C), semi-cryogenic (SC), compressed gas (CG) and
earth storable (ES)
N2O4-UDMH (nitrogen tetra oxide and unsymmetrical di-methyl hydrazine)
LOX-RP1 (liquid oxygen and kerosene)
LOX-LH2 (liquid oxygen and liquid hydrogen)
N2 (nitrogen gas)

A

N2O4 UDMH (ES), LOX-RP1 (C), LOX-LH₂ (C), N2 (C)

B

N2O4-UDMH (SC), LOX-RP1 (SC), LOX-LH2(C), N2 (C)

C

N2O4-UDMH (ES), LOX-RP1 (SC), LOX-LH2(C), N2 (CG)

D

N2O4 UDMH (ES), LOX-RP1 (C), LOX-LH₂ (C), N2 (CG)


(c) is the correct answer.

Ques 42 GATE 2009

Let M0 be the total mass of a single stage rocket, MP be the total mass of propellant, ML be the mass
of payload carried by the rocket and MS be the mass of inert structural components. If
Isp is the
specific impulse of the propulsion system (in seconds) and g is the acceleration due to gravity, then the
maximum velocity that can be attained by the rocket vehicle in the absence of gravity and atmospheric
drag is given by

A

gIspln(M0/MP)

B

gIspln(M0/ML+MS-1)

C

gIspln(M0/MS)

D

gIspln(M0/M0-MP)


(d) is the correct answer.

Ques 43 GATE 2009

The performance of a solid rocket motor is improved by replacing the old propellant with a new one.
The new propellant gives a combustion temperature 40% higher than the previous propellant without
appreciable change in molecular weight of combustion products and other operating parameters. By
approximately what percentage is the specific impulse of the new motor higher than the old one?

A

18%

B

96%

C

42%

D

112%


(a) is the correct answer.

Ques 44 GATE 2009

A solid rocket motor has an end burning grain of cross-sectional area ACS=0.4 m2. The density of
propellant is and has linear regression rate ˙r=5 mm/s. If the specific impulse of the
propulsion system is seconds, the thrust produced by the motor is approximately

A

3 kN

B

6 kN

C

1.5 kN

D

12 kN


(b) is the correct answer.

Ques 45 GATE 2009

For a plane strain problem, the stresses satisfy the condition

A

τxz=τyz=σz=0

B

τxz=τyz=0, σz=ν(σx+σy)

C

τxz=τyz=0, σz=ντxy

D

τxz=τyz=0, σz=ν(σx+σy)+(1-ν)τxy


(b) is the correct answer.

Ques 46 GATE 2009

In a thin walled rectangular tube subjected to equal and opposite forces P as shown in the figure, the
shear stress along leg AB is

A

zero

B

constant non-zero

C

varies linearly

D

varies parabolically


(b) is the correct answer.

Ques 47 GATE 2009

For the thin walled beam cross section as shown in the figure, the shear centre lies at

A

Mid point of AB, i.e. at point E

B

Mid point of BD, i.e. at point F

C

Junction point B

D

at a point G lying within the area ABC


(c) is the correct answer.

Ques 48 GATE 2009

Consider a simply supported beam of length 2L with an overhang of length L, loaded by an end

moment M, as shown below.
The bending moment distribution for this beam is

A

B

C

D


(a) is the correct answer.

Ques 49 GATE 2009

The buckling load for a simply supported column of rectangular cross section of dimensions
1cm×1.5 cm and length 0.5 m made of steel (E=210×109N/m2) is approximately

A

10 kN

B

4 kN

C

23 kN

D

46 kN


(c) is the correct answer.

Ques 50 GATE 2009

A wing root cross section is idealized using lumped areas (booms) as shown below.

The wing root bending moment in steady level flight is factor n=3.5, the maximum bending stress at the root is

A

1×106N/m2

B

3.5×106N/m2

C

7×106N/m2

D

0.286×106N/m2


(c) is the correct answer.

Ques 51 GATE 2009

A 2-celled tube with wall thickness 0.5 mm is subjected to a torque of 10 N-m. The resulting shear
flows in the two cells are q1 and q2 as shown below.

The torque balance equation (Bredt-Batho formula) for this section leads to

A

q1-q2=2000 N/m

B

q1+2q2=2000 N/m

C

q1+q2=2000 N/m

D

2q1+q2=2000 N/m


(a) is the correct answer.

Ques 52 GATE 2009

If the shaft is fixed at both ends, the boundary conditions are:

A

and ∂θ/∂x|x=0=0 ∂θ/∂x|x=L=0

B

θ(0)=0 and θ(L)=0

C

∂θ/∂x|x=0=0 and θ(L)=0

D

θ(0)=0 and ∂θ/∂x|x=L=0


(b) is the correct answer.

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