Aerospace Engineering Gate 2015 Questions with Answer

Ques 14 GATE 2015

Which one of the following aero engines has the highest propulsive efficiency?

Ques 15 GATE 2015

The stoichiometric fuel-to-air ratio in an aircraft engine combustor varies with the compressor pressure ratio as follows:

Ques 16 GATE 2015

A rocket engine produces a total impulse of 112 kN.s in a burn time period of 3.5 minutes with a propellant mass flow rate of 0.25 kg/s The effective exhaust velocity (in m/s) of gas ejecting from the engine is

Ques 17 GATE 2015

An ideal gas in a reservoir has a specific stagnation enthalpy of h₀. The gas is isentropically expanded to a new specific stagnation enthalpy of h₀/2 and velocity u. The flow is one-dimensional and steady. Then u²/h₀=_______

Ques 18 GATE 2015

Isentropic efficiencies of an aircraft engine operating at typical subsonic cruise conditions with the following components - intake, compressor, turbine and nozzle - are denoted by η_i η_c η, and η_n respectively. Which one of the following is correct?

Ques 19 GATE 2015

A rocket nozzle is designed to produce maximum thrust at an altitude, H=8 km from the sea level. The nozzle operates in

Ques 20 GATE 2015

Air enters an aircraft engine at a velocity of 180 m/s with a flow rate of 94 kg/s The engine combustor requires 9.2 kg/s of air to burn 1 kg/s of fuel. The velocity of gas exiting from the engine is 640 m/s The momentum thrust (in N) developed by the engine is

Ques 21 GATE 2015

A solid rocket motor is designed with a cylindrical end-burning propellant grain of length 1 m and diameter 32 cm. The density of the propellant grain is 1750 kg/m³. The specific impulse of the motor is 190 s and the acceleration due to gravity is 9.8 m/s². If the propellant burns for a period of 150 s, then the thrust (in N) produced by the rocket motor is

Ques 22 GATE 2015

A liquid propellant rocket has the following component masses:

Mass of payload =180 kg
Mass of fuel =470 kg
Mass of oxidizer=1170 kg
Mass of structures=150 kg
Mass of guidance systems =20 kg

The effective exhaust velocity is 3136 m/s. The velocity increment (in km/s) of the rocket at burnout, while operating in outer space, is

Ques 23 GATE 2015

Following are the operational parameters of an axial compressor stage:
Air mass flow rate =24 kg/s
Static temperature of air at the rotor inlet =278 K
Velocity of air at the rotor inlet (zero whirl velocity) =140 m/s
Work done on the compressor rotor =734 kJ
Isentropic efficiency of the compressor stage =0.86
Ratio of specific heats =1.4
Specific heat at constant pressure =1.005 kJ/kgK

The stagnation pressure ratio across the axial compressor stage is

Ques 24 GATE 2015

A centrifugal air compressor is operating at the following conditions:
Inlet stagnation temperature =288 K
Inlet stagnation pressure =1.15 bar
Exit stagnation temperature =454 K
Exit stagnation pressure =4.8 bar
The energy loss due to non-isentropic compression per unit mass of flowing air (ratio of specific heats, γ=1.4 and specific heat at constant pressure, C_p=1.005 kJ/kgK) is _______ kJ/kg.

Ques 25 GATE 2015

Hot gas (ratio of specific heats, γ=1.33) at a temperature of 1450 K enters into an axial turbine and expands isentropically. Assume that the kinetic energy of the gas across the turbine is negligible. If the ratio of inlet to outlet pressures of the turbine is 9.5, then the temperature (in K) of gas exiting the turbine is

Ques 26 GATE 2015

A cantilever with thin-walled channel cross section is subjected to a lateral force at its shear center. The cantilever undergoes