GTE - 1 aero assessment

Modular construction of gas turbine engines mainly allows

Defective parts to be replaced without replacing the whole engine

A turbojet engine is operating at high aircraft speed. The ram effect increases the pressure at the compressor inlet. This phenomenon primarily:

Restores part of the thrust lost due to higher flight speed

A turbojet flies at the speed of 324 mph, and its exhaust gas jet velocity is 745 mph at atmospheric pressure. What is its propulsive efficiency?

0.606

In the Brayton Cycle, combustion inside the gas turbine engine theoretically occurs at

Constant Pressure

A change in _________ will most directly increase the engine thrust according to the force equation.

Greater mass flow rate

During a performance test, a turbojet engine develops a net thrust of 52 kN while consuming 4,000 kg of fuel over a 40-minute test period. Determine the average thrust specific fuel consumption.

0.032 kg/(kN-s)

At higher altitudes, the gas turbine engine’s efficiency will generally

Decrease due to reduced airflow

The fuel consumption of an engine is considered economical when

SFC is as low as possible

A jet engine generates a net work of 2,800 kW. Air enters the compressor at 100 kPaa and 30°C and is compressed to 800 kPaa. After combustion, the temperature reaches 900°C. What is the mass flow rate of air

9.97 kg/s

In a by-pass engine, the by-pass air:

Increases the air mass flow and therefore increases the propulsive efficiency.

When gases pass through a convergent duct their:

Their velocity increases and their temperature and pressure decrease

In a gas turbine engine:

Thrust is maximum and ram pressure at minimum at the start of the take off run.

A rise in pressure above existing outside atmospheric pressure at the engine inlet, as a result of the forward velocity of an aircraft, is referred to as ________.

Ram pressure

A turbojet engine is travelling at 500 mph. The jet velocity is 1900 ft/s. The pressure at the jet exhaust is atmospheric. The air flow is 300,000 lb/hr and the fuel flow is 4300 lb/hr. Calculate the net thrust neglecting the fuel flow.

3021.76

The highest pressure in a gas turbine engine occurs:

Between the compressor and the combustion chamber.

In a high ratio by-pass engine:

Not all the air goes through the high pressure compressor.

The Gas Turbine Engine uses the principle of:

Newton's Third Law of motion.

A free power turbine:

Has no mechanical connection with the other turbine or compressor shafts.

The majority of the thrust of a:

Turbo-fan engine comes from the by-pass air.

Select the correct order of best propulsive efficiency, from low to high airspeed

Turbo-prop, High by-pass ratio turbo jet, Low by-pass ratio turbo jet, Pure turbo jet.

In a twin spool engine:

The L.P. turbine is connected to the L.P. compressor, the H.P. turbine is connected to the H.P. compressor.

The ring of blades which sometimes precede the first rotor stage of an axial flow compressor are called:

The inlet guides vanes.

The propelling nozzle is designed to:

Increase the velocity and decrease the pressure of the gas stream

The attachment of blades to the compressor disc:

Allows slight movement to relieve stress concentration.

Which statement best explains why turbofan engines generally require less exhaust noise suppression than turbojet engines?

Their hot and cold streams mix before leaving the engine

What is the proper starting sequence for a turbojet engine?

Starter, Ignition, Fuel

A turbine engine experiences a hot start during engine start-up. Which action should be taken immediately?

Shut off the fuel and ignition immediately

During a noise survey, two aircraft produce the same sound pressure level near the runway. Aircraft A produces predominantly low-frequency noise, while Aircraft B produces mostly high-frequency noise. Which aircraft is likely to create noise complaints farther away from the airport?

Aircraft A

Select the correct order of best propulsive efficiency, from low to high airspeed

Turbo-prop, High by-pass ratio turbo jet, Low by-pass ratio turbo jet, Pure turbo jet.

If a severe centrifugal load imposed by high operating speed is combined with elevated temperature in the turbine it will eventually may result on blades that grow in length. This type of engine damage is called?

creep

When methanol is added to a water injection system:

It is an important source of fuel and an anti-freeze.

A "Hung Start" occurs when:

The engine lights up but does not accelerate to self sustaining speed.

As air passes through an axial flow compressor, a pressure rise takes place in:

Both the rotor blades and the stator vanes.

A big fan engine gets reverse thrust by:

Blocking the by-pass air.

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

Is divergent to reduce the velocity of the gases leaving the turbine.

A complete breakdown of airflow through a compressor is known as:

Compressor surge

Water injection is used for takeoff:

Only at high altitude airfields where the prevailing temperature is high

A turbojet aircraft is scheduled for takeoff from a high-altitude airport on a hot day. Which thrust augmentation method is specifically intended to restore engine thrust under these conditions?

Water Injection

An engine reaches combustion normally, EGT remains within limits, but RPM stabilizes below idle and fails to accelerate further. This condition is called

Hung Start

What would be the possible cause if a gas turbine engine has high exhaust gas temperature, high fuel flow, and low RPM at all engine power settings?

Turbine damage or loss of turbine efficiency.