Gas Turbines - The Exhaust System: DGCA Technical General questions

Question 1

The velocity of the gases in the exhaust unit is held to:

Accepted Answer

Mach 0.5 to minimize turbulence

Answer

Mach 0.75 to optimize the pressure distribution

Answer

Mach 0.85 to maximize thrust

Answer

Mach 1 to maximize acceleration

Question 2

An exhaust nozzle is said to be choked when the velocity at the throat is:

Accepted Answer

at Mach 1

Answer

Mach 0.5

Answer

below Mach 1

Answer

above Mach 1

Question 3

The exhaust gases pass to atmosphere via the propelling nozzle which:

Accepted Answer

is a convergent duct, thus it increases the gas velocity

Answer

converts kinetic energy into pressure energy

Answer

is a divergent duct, thus it increases the gas velocity

Answer

is a divergent nozzle, thus it increases the gas pressure

Question 4

The shape of the volume within the jet pipe casing immediately to the rear of the turbine:

Accepted Answer

is divergent to reduce the velocity of the gases leaving the turbine

Answer

is convergent to accelerate the gases towards the propelling nozzle

Answer

is divergent to accelerate the gases away from the turbine blades

Answer

is convergent to increase the pressure of the gases in the jet pipes

Question 5

The exhaust cone:

Accepted Answer

prevents the hot gases flowing across the rear turbine face

Answer

straightens the gas flow before it goes into the turbine assembly

Answer

increases the velocity of the gases

Answer

decreases the pressure of the gas

6 more questions in this chapter, free with an account