Combustion and turbine

A cannular combustion system is:

• a set of flame tubes, each of which is mounted in a separate air casing

• a set of flame tubes enclosed in a common air casing

• one common flame tube enclosed in a common air casing

• superior to the annular system because it only requires one igniter

One advantage of an annular combustion chamber system is that:

• the diameter of the engine is reduced

• there is unrestricted airflow at maximum rpm

• there are no flame propagation problems

• the air casing area is greater

Swirl vanes in the combustion chamber:

• increase the velocity of the airflow

• reduce the velocity of the airflow

• prevent compressor stall

• help to stabilize combustion

Shrouding of stator blade tips is designed to:

• prevent tip turbulence

• ensure adequate cooling

• minimize vibration

• prevent tip losses

The purpose of the tertiary airflow created in the combustion chamber is to:

• reduce the gas temperature and cool the flame tube

• form a toroidal vortex, which anchors and stabilizes the flame

• reduce the gas temperature and cool the burner head

• ensure complete combustion of the fuel

The air entering the combustion chamber is divided; a small percentage is used in combustion, the rest:

• is syphoned off for airframe anti-icing purposes

• is used only for cooling the gases before they exit the combustion chamber

• is used to cool both the gases exiting the chamber and the walls of the air casing

• is used to reduce the oil temperature and cool the turbine blades

What percentage of air entering the internal combustor is used for combustion?

• 50-60%

• 65-80%

• 25-40%

• 55-70%

When would you select ‘continuous’ ignition?

• When volcanic ash clouds have been forecast in the area

• Take-off, landing and when encountering significant turbulence or precipitation

• Starting and shutting down

• When using reverse thrust

Nozzle guide vanes are fitted before the turbine:

• to increase the velocity of the airflow.

• to decrease the velocity of the gas flow therefore increasing its pressure.

• to increase the velocity of the gas flow therefore reducing its pressure.

• to increase the temperature of the gas flow.

Over temp in a turbine engine is most critical where?

• First stage of turbine assembly

• Second stage of turbine assembly

• Third stage of turbine assembly

• Fourth stage of turbine assembly