Turbine Engine Operation Test 2 Review

The primary functions of the turbine nozzles are to:

1. Convert part of the gas heat and pressure energy into air velocity

2. Raise the temperature of the gasses coming from the combustion section

3. Direct the gas flow onto the turbine blades at the proper angle.

4. Swirl the air entering the combustor to ensure a proper mixture of fuel and air.

1 & 3

The exhaust nozzle on a subsonic designed turbine engine forms a ______ section at the 2nd half after the outer cone

Convergent

The blades or buckets of a turbine rotor are normally attached to the disk by means of:

A fir tree design

Integral aircraft engine exhaust sound suppressors (hush kits):

Permit exhaust gasses to more easily mix with ambient air

For impulse type turbine blades, the area between the rotor blades:

Is straight

The loudest noise coming from the engine inlet of a turbojet aircraft is normally caused by:

Air rushing across the inlet guide vanes and being cut by rapidly moving compressor blades.

Impulse- Reaction turbine blades are designed to:

Create a uniform exit velocity from blade base to tip

What percentage of air in the combustion chamber is used for purposes other than combustion?

65% - 75%

What are the two types of thrust reversers?

Post-exit and Pre - exit

The operation of the multiple stage turbine is similar to that of the single stage, except that the succeeding stages operate at:

Lower velocities, pressures and temperatures.

For an impulse type turbine, if the turbine is fixed and unable to rotate, and a constant airflow was introduced across the blades, there would be ____ velocity across the turbine rotor blades

No change in

Hot gasses in the combustion chamber are cooled by:

Secondary air from outside the combustion chamber entering holes at the sides and rear of the combustion chamber.

A tail cone placed aft of the turbine in the exhaust duct of a gas turbine engine will cause the pressure in the first part of the exhaust to:

Increase and the velocity to decrease

What turbine engine section provides for proper mixing of fuel and air?

Combustion section

What two basic types of turbines are made for gas turbine engines?

Axial flow and radial inflow

On turbine powered airplanes, how much reverse thrust is usually required for minimum braking requirements?

50% of full forward thrust

A metal working technique used to alter the internal structure and mechanical properties of various metals is called:

Heat Treating

Ceramic coatings are particularly vulnerable to:

Thermal Shock

A ceramic coating on a hot section component has two basic functions:

1. Seal the base metal surface against corrosion, oxidation and carbonizing

2. Prevent Thermal shock.

3. Reduce erosion/wear on hot section components and insulate against high temperatures.

4. Eliminate using compressor bleed air for cooling hot section components.

1 & 3

Advantages of a through flow annular combustion chamber include:

Larger burner area uses less space

What are the two basic parts of the axial turbine in a gas engine?

Stator and rotor

The three types of turbine blades are:

Impulse, reaction and impulse-reaction

In which type of turbine combustion chamber can the case and liner be easily removed and reinstalled as one unit during routine maintenance?

Multiple can

What is meant by a shrouded turbine rotor?

The turbine blades are shaped so that their tips form a band or shroud.

Reduced blade vibration and reduced airflow loss across the turbines in a gas turbine engine are rights about by?

Shrouded turbine rotor blades.

Operating thrust reversers at low ground speeds can sometimes cause:

1. Sand or other foreign object ingestion

2. Hot exhaust gas re-ingestion

3. Compressor stalls

1, 2, 3

The an annular combustion section is made up of a series of individual inner liners and:

One outer case for all the inner liners

What is the general proper operating sequence when using thrust reversers to slow an aircraft after landing?

Retard throttles to ground idle, select thrust revers, advance throttles up to takeoff position as conditions require, retard throttles to ground idle. stow thrust reversers

Turbojet and turbofan thrust reverser systems are generally powered by:

1. Fuel pressure

2. Electricity

3. Hydraulic pressure

4. Pneumatic pressure

5. Engine oil pressure

3 & 4

All aircraft capable of supersonic flight incorporate

A convergent-divergent exhaust nozzle.

Interconnectors in multiple can and can annular combustors function primarily to:

Help flame propagate from one can to another during starting.

Which combustor type requires the least cooling air for a given gas temperature?

Annular through flow

The air used to cool the turbine blades and vanes is extracted from

The compressor or diffuser.

The radial inflow turbine is used primarily in

Small turboshaft engines

Which combustor type has the disadvantage of decreased efficiency because the air is required to make two 180 turns inside the engine?

Reverse flow annular combustor

In multiple stage turbine applications, less blade area is required for each succeeding stage.(true or false)

False

For reaction type turbines, the area between the stator vanes forms a divergent duct. (true or false)

False

Only about 1/4 to 1/3 of the air leaving the compressor section of a gas turbine engine enters the combustion liner to support the combustion process (true or false)

True

All aircraft turbine engines must be equipped with a variable geometry exhaust nozzle (true or false)

False

Secondary combustor air enters the holes at the rear and sides of a combustion liner and is primarily used for cooling the combustion gasses and for keeping the burning gasses centered in the combustion liner (true or false)

True

As the primary combustor air enters the combustion chamber, it passes through ____ ____ ( not every has them) which reduce the axial velocity of the airflow and increases the radial velocity.

Swirl vanes

Titanium is mainly used in which turbine engine section on thrust producing engines.

Cold

For impulse turbines, the blades use Newton's ___ Law of Motion as a basis for propelling the turbine rotor.

2nd

Reaction type turbines use Newton's ___ Law of Motion as a basis for propelling the turbine rotor.

3rd

What type of combustor is used on the Allison 250 turboshaft engines located in the shop?

Revers flow annular