105 Questions
What is a common method to boost power output during take-off in gas turbine engines?
Pumping additional air to increase intake air density
Why do very few modern gas turbine engines use fluid injection to augment thrust?
New turbofan engines have enough thrust capability
What is afterburning in the context of gas turbine engines?
Combusting fuel after the turbine with remaining oxygen
Which type of engines are more likely to benefit from fluid injection to augment thrust?
Engines of commuter and small aircraft
How does cooling compressor or pre-combustion airflow help boost power output during take-off?
By increasing intake air density
What is one of the effects of afterburning in gas turbine engines?
Augmenting thrust at the exhaust nozzle
What is the primary purpose of power augmentation systems in engines?
To provide a short-term boost to engine power
Which of the following is NOT a type of fluid injection system mentioned in the text?
Oil Injection
What is the main function of an afterburner in an aircraft engine?
To increase thrust
Which component is responsible for providing fuel to an afterburner system?
AB Fuel Pump and Fuel Control
In the context of power augmentation, what role do spray manifolds and flame retainers play?
Help in fuel atomization and combustion stabilization
Which system enhances power by injecting water or water/methanol mixtures into the engine?
Power Augmentation System
What is the function of the screech liner in an afterburner system?
Stabilize combustion and prevent oscillations
Which component of the afterburner layout is responsible for igniting the fuel mixture?
Ignition Systems
What is the main purpose of fluid injection in aircraft engines?
To increase the airflow density and mass flow
Which component of the engine does fluid injection primarily cool when added at the compressor inlet?
The air after compression
How does fluid injection at the diffuser affect the engine's airflow?
It increases the velocity and pressure of the gasflow at the jet pipe
What effect does heat transfer from fluid droplets to the air have on engine performance?
Increases airflow density
In what way does additional fuel in the combustor contribute to engine thrust?
Increases velocity and pressure of gasflow
What is the primary result of using a fluid injection system in terms of engine performance?
Boost in thrust by 10% to 30%
What is the purpose of the tank-mounted sight gauge in the Metroliner fluid injection system?
To determine the tank's fluid quantity
In the Metroliner fluid injection system, what is the function of the check valves fitted on each pump?
To prevent pressure bypass in case of pump failure
Where does the fluid travel after passing through the firewall valve in the Metroliner fluid injection system?
To the engine inlet
What triggers a cockpit indicator light to signal that a pump is operating in the Metroliner fluid injection system?
Pressure switch on the pumps
What is the role of the cockpit quantity indicator found on some aircraft models with the Metroliner fluid injection system?
To indicate fluid quantity in the tank
How is fluid supplied from the tank to the right hand side wing root area in the Metroliner fluid injection system?
Through a firewall valve
What is a benefit of water/methanol injection systems over water injection systems?
Reduced need for refilling the injection system before each take-off
Why does water injection provide more engine performance increase compared to water/methanol injection?
Water injection systems prevent fuel from being added to the engine
In what scenarios can the Metroliner aircraft's fluid injection system be operated?
Emergency mode for engine failure or continuous mode for performance augmentation
How do fluid injection systems assist gas turbine engines during take-off?
By boosting engine power without increasing fuel flow
What is a primary advantage of water/methanol injection systems despite not maximizing engine performance like water injection systems?
Reduced freezing issues compared to water injection systems
Why does a gas turbine engine perform better with water injection than with methanol?
Methanol has a lower calorific value than water
What is the consequence of further throttle movement beyond the AB range in a gas turbine engine?
Variable area nozzle closes completely
How does a variable area nozzle being fully closed at maximum nonafterburning power affect the engine performance?
Reduces engine thrust
Which component of the afterburner system serves the purpose of igniting the fuel mixture?
AB flame retainers
In what scenarios can a gas turbine engine benefit from fluid injection to augment thrust?
During take-off and emergency situations
What is the primary function of afterburner screech liners in an aircraft engine?
Reducing noise levels
Why would a gas turbine engine perform better with water injection than with methanol?
Methanol has a lower combustion efficiency
What happens when the power levers are advanced past flight idle in the Metroliner fluid injection system?
Fluid flows into the engine's spray manifold
What does the selector switch being in the ARM position indicate in the Metroliner fluid injection system?
Power supplied to the arming circuit
What causes the pump indicating light in the cockpit to illuminate during operation of the Metroliner fluid injection system?
Fluid pressure reaching 30 PSI
How does the system ensure that flow ceases to an engine in the Metroliner fluid injection system?
If the engine develops less than 600 foot-pounds of torque
What is the primary function of the engine torque pressure switch in the Metroliner fluid injection system?
To sense engine torque pressure
In what position does the selector switch need to be for electrical power to be removed from the pump and arming circuits in the Metroliner fluid injection system?
OFF
When will the control box open the firewall valves in the Metroliner fluid injection system?
When low torque is sensed by the torque switch in one engine
What must be met for fluid to be delivered to both engines in the Metroliner fluid injection system when the selector switch is in the CONT position?
Power levers forward of the flight idle gate and engine producing more than 600 foot-pounds of torque
What enables fluid injection to the remaining operating engine in the Metroliner fluid injection system?
Low torque sensed by a torque switch
In the Metroliner fluid injection system, what conditions are needed for the control box to open the firewall valves?
Power levers forward of flight idle gate and low torque sensed by a torque switch
What triggers fluid delivery to both engines in the Metroliner fluid injection system when the selector switch is in the CONT position?
Power levers forward of flight idle gate
How does the firewall valve operation change in the Metroliner fluid injection system when fluid is supplied to both engines?
Both firewall valves close to prevent flow
What is the purpose of the engine torque pressure switch in the Metroliner fluid injection system?
To sense engine torque pressure
What triggers the pump indicating light in the cockpit to illuminate during operation of the Metroliner fluid injection system?
30 PSI fluid pressure buildup
In the Metroliner fluid injection system, what happens when the selector switch is set to OFF?
Tank quantity indicator stops functioning
What indicates that the Metroliner fluid injection system is in ARM mode?
Cockpit ARM light illuminated
What ensures that flow ceases to an engine in the Metroliner fluid injection system?
Engine developing more than 600 foot-pounds of torque
What happens to exhaust gas temperature during afterburning in aircraft engines?
It increases to around 1,700°C
Why is the duct pressure relatively constant during afterburner operation in aircraft engines?
To maintain back pressure on the main engine
What component in an afterburner system supports combustion by creating recirculating gas patterns?
Flame retainer
In the context of afterburner screech, what is the primary role of screech liners?
Absorbing and dampening pressure fluctuations and vibrations
What causes a gas turbine engine to ignite the mixture in an afterburner system as per the text?
Spraying fuel into the flame area
What is the purpose of spray manifolds in an afterburner system?
Supplying fuel to the flame area
What role does the diffuser play in an afterburner system based on the text?
Affecting engine airflow
Which component's chemical reaction in an afterburner system generates sufficient heat to ignite the mixture?
Flame retainer
What is the primary difference between hot shot ignition and spark ignition systems?
The method of fuel injection
How does catalytic ignition differ from hot shot and spark ignition methods?
It does not require an igniter plug
In a hot shot ignition system, where does the flame from the combustion chamber travel after exiting the turbine?
To ignite the AB mixture
What is the main role of the igniter plug in a spark ignition system?
To ignite the main engine's fuel flow
How does the operation of catalytic ignition systems differ from spark and hot shot ignition systems?
They do not ignite fuel streams
In which type of ignition system does the igniter plug operate independently of the main engine's ignition system?
Spark ignition
What is the function of catalytic ignition in AB systems?
Ensure proper combustion at low temperatures
What is the primary purpose of spray manifolds in AB systems?
Ensure even fuel distribution
Which component in an aircraft engine is responsible for ensuring normal engine operation during afterburner use?
Pressure ratio control unit
What triggers the operation of the AB fuel pump and fuel control in aircraft engines?
Main engine fuel control signal
What is the primary function of the variable area nozzle on afterburning engines?
To minimize the propelling nozzle area during high power operation
How does the variable area nozzle respond to afterburner (AB) selection?
By opening in stages based on the amount of AB selected
What will happen to the pressure in the afterburner duct if the nozzles remain closed when AB is selected?
It will rise dramatically
How does a modern engine's variable area nozzle affect engine performance when fully closed at maximum non-afterburning power?
It does not affect engine performance significantly
What drives the series of interlocking flaps in a variable area nozzle?
Actuators or rams
In what way does the variable area nozzle contribute to engine efficiency during high power normal operation?
By minimizing propelling nozzle area to optimize performance
What is responsible for controlling the movement of the nozzle flap in aircraft engines?
Pressure ratio control unit
How is the exhaust nozzle opened and closed in aircraft engines?
By hydraulic actuators powered by aerodynamic forces
What leads to an increase in exhaust area in aircraft engines?
Out of balance condition between hydraulic actuator load and gas load
How does the pressure ratio control unit restore balance in aircraft engines?
By altering exhaust nozzle area
What is the main role of the pressure ratio control unit in aircraft engines?
To restore balance between hydraulic actuator load and gas load
What is the purpose of a two-position nozzle in an afterburning engine's exhaust system?
To control the rapidly expanding gas during afterburner operation.
In aircraft engines, why does an out of balance condition between hydraulic actuator load and gas load lead to an increase in exhaust area?
To restore pressure ratio P3 / P6
What differentiates a two-position nozzle from a variable area nozzle in afterburning engines?
The two-position nozzle controls gas flow by fully opening or closing, while a variable area nozzle adjusts its diameter.
Why are concave flaps or eyelids used in a two-position nozzle of an afterburning engine?
To control gas flow by opening or closing positions.
What is the main function of a variable area nozzle in an afterburning engine?
To adjust the diameter to optimize engine performance.
How do two-position nozzles differ from variable area nozzles in terms of operating mechanism?
Two-position nozzles have fixed positions, while variable area nozzles adjust their diameter.
Why is it critical to have precise control over the gas flow in an afterburning engine system?
To optimize engine performance during different operating conditions.
Why might a gas turbine engine benefit from afterburning?
To boost thrust for additional power
What is the significance of moving the throttle beyond the AB range in a gas turbine engine?
May lead to engine damage
What effect does a fully closed variable area nozzle have on an afterburning engine during maximum nonafterburning power?
Reduces exhaust airflow
Why is it crucial for the AB flame retainers to be present in afterburning engines?
To prevent flameout in the combustion chamber
What is a primary reason for using fuel injection to boost engine power during afterburning?
Enhance thrust output
What is the purpose of the pressure ratio control unit in an afterburner system?
To ensure that pressure in the afterburner duct does not affect normal engine operation
Why do AB systems use an additional engine fuel pump and fuel control?
To ensure large fuel flows required by afterburners are met
What triggers the opening of the valve to allow fuel into the afterburner fuel pump inlet?
Fuel pressure signal from the main engine fuel control
How does an afterburner ignition system primarily ignite the fuel mixture?
Hot shot ignition
What is the role of spray manifolds in an afterburner system?
To distribute fuel evenly for combustion
In what way does the variable area exhaust nozzle contribute to afterburner operation?
By regulating pressure in the afterburner duct
In what position are the concave flaps of a two-position nozzle typically when the engine is operating without afterburner?
Fully closed
What is the critical factor in controlling the rapidly expanding gas during afterburner operation?
Variable area nozzles
What role do concave flaps play in an afterburner system equipped with a two-position nozzle?
Modulate between fully closed and fully open positions
This resource document from Defence Aeroskills Training Academy covers topics related to gas turbine engine systems and power augmentation. It provides valuable information for students studying aviation engineering.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
