Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
2a353 Volume 3 CH 3
USAF Tactical Aircraft Maintenance CDC Questions 2016
| Question | Answer |
|---|---|
| When the opening of a filled balloon is closed, why is there no action on the balloon? | Because the pressure of the gas inside the balloon is exerted equally in all directions |
| What type of energy does a falling object possess? | Kinetic energy |
| Can energy pass from potential to kinetic and back to potential? | YES |
| What is Newton's 1st Law of Motion? | A body at rest remains at rest and a body in motion continues to move at a constant speed in a straight line, unless acted upon by an external force |
| What is Newton's 2nd Law of Motion? | An unbalanced force on a body produces, or tends to produce, an acceleration in the direction of the force, and that acceleration is directly proportional to the force and inversely proportional to the mass of the body |
| Which law of physics best explains how a jet engine produces forward thrust? | Newton's 3rd Law of Motion |
| State Bernoulli's principle | When the speed of a stream of gas increases, the pressure of the gas decreases, and when the speed of the gas decreases, the pressure increases. |
| When a jet engine reaches idle, what determines how the fuel control regulates engine speed? | Power Level Setting |
| What two forms of energy does a jet engine produce? | Thrust and heat |
| Approximately what percent of the energy produced by the fuel is needed to maintain the jet engine operating cycle? | 60% |
| Where is the point of highest pressure within a jet engine? | In the diffuser section |
| On a jet engine that does not have an afterburner, where is the point of highest temperature? | In the combustion section |
| Where is the point of highest airflow velocity in a jet engine? | At the ejector nozzle |
| What is the purpose of the turbine stator? | To increase the velocity of the gases striking the turbine blades |
| After the gases leave the turbine section and enter the exhaust section, what type of velocity do they have? | Axial |
| What straightens the flow path of gases in the exhaust cue? | The vanes in the exhaust case |
| In a multistage turbine, what is the arrangement of the shafts? | One shaft is hollow, allowing the other shaft to operate inside it |
| Which turbine drives the front compressor on a dual spool engine? | The rear turbine |
| What is a turbojet engine? | An air-dependent, thermal, jet propulsion device |
| Name the three main sections of a gas turbine engine | Compressor, combustion chamber, and turbine |
| What are the 2 types of compressors used in jet engines? | Centrifugal and axial flow |
| How do pressure pulsations in a centrifugal compressor present themselves? | As shock waves or irregular movement of air through the compressor |
| What effect do pressure pulsations have on a compressor? | Rapidly reduced efficiency |
| Why is it not desirable to use multi-stage centrifugal compressors to increase the pressure ratio? | Because of the complicated construction and increased weight of the engine that would result |
| What two needs stimulated the development of the axial flow compressors? | More power and a more economical engine |
| How does the air pass through an axial flow compressor? | The air travels rearward along the xis of the engine, and the air pressure is increased at each stage of compression |
| How are axial flow compressor rotor blades similar to an aircraft propellor? | They both are airfoil shaped and move an air mass |
| What is the purpose of the stationary vanes that are located behind each rotor wheel in the single-spool axial flow compressor? | They direct the air onto the blades of the succeeding rotor wheel and also cause the air pressure to increase |
| How are the compressor rotor blades and stator vanes arranged in a multiple-stage, axial flow compressor? | The rotor blades are graduated from long to short through the stages of compression. The stator vanes are also granted in size to correspond in length with the rotor blades. |
| Identify 2 reasons the dual spool axial flow compressor was designed | Ease of starting and reduction compressor stalls |
| What unit determines the speed of the N2 (high pressure) rotor in a dual spool compressor? | The fuel control |
| Which type of compressor is more durable, the axial flow or the centrifugal? | Centrifugal |
| Why is getting good combustion in a gas turbine engine so complex? | Because the fuel and air must combine rapidly, the combustion process must not use excessive energy and space, and the combustion chamber must not overheat |
| What is combustion efficiency? | A measure of the ability of the combustion chamber to burn the fuel completely and to mix the elements throughly with the remainder of the air charge before the gases reach the turbine nozzle |
| How is combustion efficiency computed? | By comparing the heat energy received by the air as it passes through a test combustion chamber with the known energy that was added to the chamber in the form of fuel |
| What are two by products of combustion? | Carbon deposits and carbon monoxide |
| What are the 2 purposes of the combustion section? | To burn the fuel and to deliver the resulting gas to the turbine at a temperature that does not exceed a predetermined limit for the particular engine in use |
| What is the approximate air to fuel ratio used for the actual burning process in a combustion chamber? | 15:1 |
| Name the 3 types of combustion chambers | Can, annular and can-annular |
| What supports the annular type combustion chamber in the front and the rear? | The front of the chamber is attached to the burner support, and the rear of the chamber is supported on the outside by the stator blade support ring of the first-stage turbine and on the inside by the stator inlet ring of the first stage turbine |
| How does the additional air that is required to support combustion and cool the annular combustion chamber reach the chamber walls? | Through elongated slots and round holes in the sections of the chamber walls |
| What supports the can-annular combustion chambers within the combustion section on certain engines? | Fuel nozzles in the front and turbine nozzle case at the rear |
| What is the purpose of a fuel nozzle? | To introduce fuel into the combustion chamber |
| Multiple fuel nozzles are used for what 2 purposes? | To handle large quantities of fuel with even distribution and to minimize the variation that might be caused by a clogging of any one of the nozzles |
| In a dual-orifice type of fuel nozzle, fuel is injected into the engine combustion chamber from which orifices for high engine thrust operation? | Both the Primary and secondary orifices |
| Name the 3 types of turbines | Impulse, reaction, and reaction impulse |
| What type of turbine design is used on most jet engines? | Reaction impulse |
| What is inserted between the rotating blades on multi stage turbines? | Stationary turbine nozzle vanes |
| What characteristics and values must be considered when designing turbines? | Exhaust gas flow rate, shaft RPM, turbine inlet and outlet temperature and pressures, turbine exhaust velocity, and the required power output |
| What is the most frequently used method of attaching the turbine blades to the rotor disc? | The Fir tree method |
| Describe the Fir tree attachment | A series of grooves and notches broached in the rim of the turbine rotor disc |
| What 3 types of fasteners are used to secure the turbine blades to the rotor discs? | Steel pins, lock strips, and rivets |
| What are the two principal turbine blade configurations? | Shrouded and un-shrouded |
| What 3 things does the shroud on shrouded turbine blades do? | Reduce blade vibration, improve airflow, and increase engine efficiency |
| The term exhaust duct refers to what? | The engine exhaust pipe connecting the turbine outlet and the jet nozzle of a non-augmenter engine |
| What are the 2 purposes of the engine exhaust duct? | To collect and straighten the gas flow that comes from the turbine and to increase the velocity of the gases before they are discharged from the exhaust nozzle |
| What may occur if you alter the exhaust nozzle? | Changes in engine performance and exhaust gas temperature |
| Why are small tabs placed in the engine exhaust nozzles of some engines? | To correct exhaust gas temperature |
| An augmenter is classified as what type of engine? | A ramjet engine |
| What is the purpose of a variable area orifice at the augmenter exhaust nozzle exit? | TO schedule the nozzle area to obtain the desired thrust within the safe operating limits of the engine |
| What effect should augmenter operation have on engine operation? | None |
| Define the term screech | A condition of periodic violent pressure fluctuation in the augmenter duct, resulting from cyclic vibration due to the unsteady release of combustion energy |
| What two parts will most likely deteriorate or fail if moderate or severe screech is not checked? | The flame holder or augmenter duct |
| How is screech controlled? | By placing screech liners in the Augmenter duct |
| What 2 things does the flame holder in the augmenter do? | Creates local turbulence and reduces the gas velocity in the vicinity of the flame |
| What are 2 drawbacks of the turbojet engine? | Inefficient fuel use when flown below Mach 2 speeds and the amount of noise they generate |
| What makes the turbofan engine more desirable than basic turbojet engines? | Capable of turbojet performance at higher speeds, while maintaining the shorter takeoff capability offered by the turboprop engine |
| What are the major sections of a turboprop engine? | Reduction gearbox assembly, a torquemeter assembly, and a gas turbine power section |
Created by:
wcarrel11
Popular Military sets