Gas Turbine Plants pt. 1

What type of seal is used in the gearbox of a gas turbine engine?

Carbon ring

The two basic types of compressors used in gas turbine engines are which of the following?

Centrifugal and axial

For the GE LM2500 gas turbine engine shown in the illustration, the GP turbine 2nd stage nozzle vanes are cooled by which of the following? Illustration GT-0020

13th stage compressor air

"Standard day" conditions, as defined by the ISO, is which of the following?

29.92 in HG @ 15 deg C AND 14.69 psi @ 59 deg F

How many shock mounts are used to secure the GE LM2500 gas turbine enclosure to the ship's foundation?

32.

A centrifugal compressor assembly consist of which of the following?

A rotating impeller and a stationary diffuser.

The fuel oil system of a gas turbine engine provides all EXCEPT which of the following?

Acts as a cooling medium for the lube oil cooler

What is the term given to a process that occurs without a loss of a gain of heat?

Adiabatic

Kelvin is the absolute temperature scale that corresponds to which of the following?

Absolute reading of a measured temperature in degrees Celsius

Rankine is the temperature scale that corresponds to which of the following?

Absolute reading of a measured temperature in degrees Fahrenheit.

Which of the following wrenches should NOT be used while working on a gas turbine?

Adjustable wrench

What type of combustor is used by the GE LM2500 gas turbine?

Annular

What is the most common type of spark igniter used on a gas turbine engine?

Annular gap

For the GE LM2500 gas turbine engine shown in the illustration, the GP turbine 2nd stage blades are cooled bu convection, with the cooling air being discharged where? Illustration GT-0011

Blade tips

In order to get a ready indication for a normal start with an GE LM2500 gas turbine engine, what permissive(s) must be met?

Bleed air valve must be closed, GG speed must be less than 1200 RPM and all engine trips reset, AND fuel supply pressure must be greater than 8psig

Turbine disks are commonly attached to the shaft by which of the following methods?

Bolted or welded

Which of the following instruments is designed to help you when preforming an internal inspection of the gas turbine engine?

Borescope.

When removing the gas turbine engine as shown in the illustration, how is the engine removal accomplished? Illustration GT-0022

By removing the inlet scree, barrier wall and module front panel, then installing the rails and moving the engine into the into the engine room and up through the the soft patch to the main deck.

How is the HP turbine rotor of the GE LM2500 gas turbine cooled?

By the ship's service seawater cooling sytstem

Compressor surge is caused by which of the following factors?

Interrupted airflow.

The three most common types of combustors used in gas turbine engines are which of the following?

Can, annular, and can-annular

A centrifugal-flow gas turbine uses what type of combustion chamber?

Can.

In comparing centrifugal-type to an axial-type air compressor, which of the following statements is true?

Centrifugal compressors have a higher compression ratio per stage than axial flow.

While air is being compressed in a centrifugal flow gas turbine, what happens to the direction of air flow?

Changes at each separate component.

How is the clutch shown in the attached illustration engaged? GT-0018

Clutch engages automatically when input shaft flange is rotating faster than the output assembly.

In a gas turbine engine, the majority of energy is added to the working fluid in which of the following components?

Cobustor

Why is a gas turbine considered to operate on the Brayton Cycle?

Combustion occurs with no increase in pressure.

HP turbine blades are generally cooled by which of the following methods?

Compressed air entering the root and exiting the tip

The acronym CDP stands for which of the following?

Compressor Discharge Pressure

In the ignition system of a gas turbine engine, how is optimum spark achieved?

Concentration of maximum energy in maximum time

On the GE LM2500 gas turbine engine, magnetic pickups are utilized for what purpose?

Determining gas generator speed, calculating engine torque, AND determining power turbine speed.

In a centrifugal compressor, which component reduces the velocity and increases the static pressure of the air?

Diffuser

Before combustion can occur, the combustion air must be delivered to the combustor at a high-pressure and low-velocity. High-velocity, low-pressure air is converted to high-pressure, low-velocity air at what part of the centrifugal type compressor?

Diffuser.

Two functions of the compressor stator vanes include which of the following?

Direct air flow to each rotor stage at the correct angle and deliver air to the combustor at the correct velocity and pressure.

Variable stator vanes give an axial gas turbine compressor which of the following capabilities?

Efficiency at various speeds.

Which of the following components prevent(s) objects smaller than 1/4 inch from entering the GE LM2500 gas turbine engine?

FOD screens

Which of the following designs is the most satisfactory method for attaching turbine blades to the rotor disk?

Fir-tree design

What type of air seal is used to the combustor and turbine mid-frame of the gas turbine?

Fishmouth

Mechanical work is defined as which of the following?

Force acting through a distance

Which of the following statements correctly describes force?

Force has magnitude and direction.

The acronym FOD stands for which of the following?

Foreign Object Damage

The sturts of the GE LM2500 compressor front frame provide passages for all fo the following mediums EXCEPT which of the following>

Fuel Oil

As shown in the illustration of a gas turbine fuel oil system, when the engine fuil oil valves are de-energized, the remaining fuel left in the system is recirculated back to which of the following? Illustration GT-0021

Fuel pump inlet

The acronym GG represents which of the following?

Gas Generator

In a twin spool turbine, secondary air is most essential in cooling what section?

HP turbine.

Which of the following terms refers to thermal energy in transition?

Heat

Accelerators are generally used on gas turbine engines to sense which of the following?

High frequency vibration

Which of the following statements concerning fluid flow is true?

If a fluid flowing through a tube reaches a constriction of a narrowing of the tube, the velocity of the fluid flowing though the restriction increases and the pressure decreases.

The divergent area of the exhaust duct aids in what process?

Increasing the volume of the exhaust gases.

What is the term used to describe the stationary vanes preceding the first stage of an axial compressor?

Inlet guide vanes

To keep the exit pressures relatively constant across an HP turbine blade, which type of construction is generally utilized?

Impulse-reaction

Thermal energy is the only form of energy that can be added or removed from a substance. How is thermal energy that is added to a substance stored?

In the form of internal energy.

Provisions for avoiding the build-up of ice on the intake air surfaces of a gas turbine plant can be found where?

In the inlet duct frame at he inlet to the engine AND in the exhaust and intake ducting

The brayton Cycle is a series of events best described by which of the following statements?

Intake, compression, combustion, expansion, exhaust

The thermal energy added to the gas as it flows through the combustion section has what effect on the gas?

Increase in volume

The main reduction gear preforms which of the following functions?

It transfers high-speed gas turbine rotation to low-speed propeller rotation.

What type of seal is used in the sump and turbine areas of a gas turbine engine?

Labyrinth-honeycomb

What type of main reduction gear arrangement prevents independent axial and rotational movement of the pinions?

Locked train

The acronym MFC represents which of the following?

Main Fuel Control

The term "divergent" is best described as which of the following?

Moving away from each other, as the inner walls of a tube that flare outward.

Wrenches that are recommended for use on a gas turbine engines should be plated with which of the following elements?

Nickel

Where are the carbon dioxide nozzles located in the GE LM2500 gas turbine enclosure?

On the cross beam under the compressor front frame.

In a gas turbine propulsion installation, the typical control system is designed to preform which of the following three functions?

Operational control, safety control, and monitoring

Which of the following statements is true about the "lockout control" on the Synchro-Self-Shifting (SSS) clutch?

Permits operation of the GTE without the rotation of the main reductin gear

For the GE LM2500 gas turbine shown in the illustration, the 9th stage bleed air is used for which of the following? Illustration GT-0017

Power turbine cooling

What feature is commonly used on articulated reduction gear arrangements for correction of misalignment between the 1st reduction gear and the 2nd reduction pinions?

Quill shafts

When a compressor is in a stall condition, what will happen to the combustor and turbine temperatures?

Rapidly increase.

On a propulsion marine gas turbine, if full power temperature become excessive, what action should the operator take?

Reduce power to stay within limits.

When working in or around intake areas, which of the following precautions should be taken?

Remove all loose objects from your clothing, inspect the intake for cleanliness, AND account for all tools and equipment.

Gas turbine fuel manifold pressure is established by which fo the following actions?

Rotating the gas generator.

The term "lockout" on the Synchro-Self-Shifting (SSS) clutch system means that the _____

SSS cluch will not engage

What is the power source for the ignition exciter of a gas turbine engine?

Ship's 115 VAC sytem

If the lube oil scavenge temperature exceeds 300 degrees Fahrenheit on the gas turbine engine shown in the illustration, and reducing power does NOT bring the temperature within limits, the operator should do which of the following? Illustration GT-0017

Shutdown the engine and troubleshoot.

THe gas generator section of the GE LM2500 gas turbine is composed of all of the following components EXCEPT which of the following?

Six stage LP turbine.

In a gas turbine, the air change is permitted to be compressed adiabatically by what factor, process, or condition?

Speed of the process

The two main types of compressor stall are known as what?

Steady state and transient.

In order to get a ready indication for a normal start on an GE LM2500 gas turbine engine, what permissive(s) must be met?

Sump pressurization and cooling, power turbine balance piston cavity pressurization, AND power turbine cooling.

What is the term given to the condition in which cyclic pressure changes result in repetitive failure and recovery of compressor air flow?

Surge

Which of the following is the definition of absolute temperature?

Temperature measured with reference to the theoretical temperature at which all molecular motion stops.

Which of the following could cause compressor stall?

The angle at which air air strikes the compressor rotor blades is too high.

Which of the following statements is true regarding centrifugal compressors?

The centrifugal compressor is frequently used on small, low power turbines

Rotation of the Controllable Pitch Propeller (CPP) blades is achieved through axial movement of what component in the hub body assembly?

The crosshead.

What is the disadvantage of a dual-entry centrifugal compressor compared to a single-entry centrifugal compressor?

The dual-entry utilizes a more complicated inlet ducting.

Potential energy is defined as which of the following?

The energy a body posses due to its position

Which of the following statements is true concerning the fuel oil ignition system of the gas turbine engine shown in the illustration GT-0017?

The igniters will de-energize when the gas generator exceeds a preset RPM.

Why is the cycle efficiency higher in the intercooled-recuperated cycle as compared to a simple cycle gas turbine? Illustration GT-0031

The intercooler serves to reduce the required high-pressure compressor power while the recuperator utilizes waste heat from the exhaust to decrease required fuel to achieve the turbine inlet temperature.

Power is defined as which of the following?

The rate of doing work

When working with gas turbine synthetic lube oil, which of the following safety measures should always be observed?

Thoroughly wash any area of skin contact, avoid prolonged inhaling of vapors, AND wear eye protection and rubber gloves.

What is the primary function of the main fuel control on the GE LM2500 gas turbine engine?

To control stator vane angle and GG speed.

What is the function of the stator in an axial gas turbine compressor?

To convert velocity to pressure.

What is the purpose of the spring in a lip-type oil seal?

To keep the neoprene snugly fit around the shaft

What is the primary purpose of the diffuser and distributor on the GE LM2500 gas turbine?

To provide uniform airflow to the combustor

The purpose of the main reduction gear in a marine gas turbine installation is which of the following?

Transfer high-speed gas turbine rotation to low-speed propeller rotation

How do you manually lockout an SSS clutch?

Using the special wrench provided

How can compressor stall be prevented?

Utilize a two-spool compressor rotor, Lowering the angle of attack on the front stages, AND installing air bleed valves in the middle of the compressor.

The Acronym VSV stands for which of the following?

Variable Stator Vane

An axial compressor stator vane that is mechanically adjusted to provide optimum compressor performance over a wide operating range is referred to as which of the following?

Variable Stator Vane (VSV)

Displacement, velocity, and acceleration describe three types of which of the following?

Vibration sensors.

For the GE LM2500 gas turbine engine shown in the illustration, the 13th stage bleed air is used for which of the following? Illustration GT-0017

high pressure turbine 2nd stage nozzle cooling

The only hand tools that should be used on a gas turbine engine are chrome plate, nickle plated, or which of the following?

un-plated