Gas Turbine Engine Fundamentals

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Questions and Answers

What is the formula that represents the relationship between force, pressure, and area in a gas turbine engine?

F = A/P

F = P·A (correct)

F = P/A

F = P + A

Which statement best describes how thrust is generated in a gas turbine engine?

Thrust relies on the pressure difference between stages of the compressor.

Thrust is generated from the reaction to the mass flow of accelerated gases. (correct)

Thrust is produced solely by the velocity of the exhaust gases.

Thrust results from energy creation in the combustion chamber.

In the context of a gas turbine engine, work is defined as:

The output of thrust generated by the turbine.

The transfer of energy to a body by a force that moves the body. (correct)

The transfer of energy without the application of force.

The energy lost in heat forms during combustion.

What role does atmospheric air play in a gas turbine engine?

It is compressed and accelerated to create thrust. Signup and view all the answers

Which physical principle is essential for understanding jet propulsion?

Newton's Laws of Motion Signup and view all the answers

Which components are primarily involved in the creation of useful work at the turbine wheel in a gas turbine?

Nozzle guide vanes and compressor stages Signup and view all the answers

What does the term 'mass flow of gases' refer to in a gas turbine engine?

The quantity of air entering and exiting the engine. Signup and view all the answers

What is one of the primary functions of nozzle guide vanes in a gas turbine engine?

To direct the flow of air towards the turbine wheel. Signup and view all the answers

What is the primary factor that differentiates velocity from speed?

Velocity includes the direction of motion. Signup and view all the answers

According to Bernoulli's Principle, what remains constant throughout a moving fluid column?

Total energy Signup and view all the answers

In a gas turbine engine, what role does burning fuel play in relation to air flow?

It accelerates the mass of air passing through the engine. Signup and view all the answers

How is momentum defined in the context of physics as described in the content?

The product of mass and velocity. Signup and view all the answers

What occurs to the pressure of a fluid as its velocity increases in a duct according to Bernoulli's Principle?

The pressure decreases. Signup and view all the answers

When analyzing the flow of fluid in a duct, what happens to the product of velocity and pressure at different points in the duct?

It remains constant between points of measurement. Signup and view all the answers

What is a key characteristic that defines speed?

It is constant regardless of direction. Signup and view all the answers

Which of the following statements about kinetic and potential energy is true as per Bernoulli's Principle?

The sum of kinetic and potential energy remains constant in a fluid flow. Signup and view all the answers

What is the primary principle behind all aircraft propulsion?

Every action has an equal and opposite reaction Signup and view all the answers

Which ancient device is credited with the concept of thrust similar to modern engines?

Hero's aeolipile Signup and view all the answers

How does aerodynamic action produce thrust in an aircraft?

By rotating a propeller that generates lift Signup and view all the answers

What is a characteristic feature of jet reaction engines?

They produce thrust by accelerating a mass of air rearward Signup and view all the answers

What role did the Chinese play in the development of propulsion systems?

They devised solid-fuel rockets Signup and view all the answers

What mechanism does an engine use to achieve thrust through aerodynamic action?

Turning a propeller that generates lift Signup and view all the answers

Which of the following statements best describes the operation of a rocket engine?

It generates thrust by igniting fuel to release heated gases Signup and view all the answers

What comparison is made to explain the principle of thrust generation in jet propulsion?

The operation of a rotating lawn sprinkler Signup and view all the answers

Which event does the Brayton cycle share with the Otto cycle?

Intake of air Signup and view all the answers

What is a primary characteristic of the Brayton cycle compared to the Otto cycle?

Constant pressure Signup and view all the answers

During which phase of the Brayton cycle does the volume of the air decrease?

Compression Signup and view all the answers

How does the process of energy addition in the Brayton cycle differ from that in the Otto cycle?

It occurs at constant pressure Signup and view all the answers

At which point does the pressure remain relatively constant during the Brayton cycle?

Between points B and C Signup and view all the answers

What is the main effect of adding heat energy in the combustion chamber of the Brayton cycle?

Increasing the air volume and temperature Signup and view all the answers

At what stage does the air exit the compressor in the Brayton cycle?

Point B Signup and view all the answers

Which aspect of the Brayton cycle distinguishes it from engines with reciprocating cycles like the Otto cycle?

The events happen simultaneously at different locations Signup and view all the answers

What occurs to the air as it moves from point A to point D in the turbine?

The air experiences a pressure drop but increases in velocity. Signup and view all the answers

What is a key advantage of gas turbines over reciprocating engines?

Gas turbines are less susceptible to vibrations. Signup and view all the answers

Which part of the gas turbine is predominantly responsible for converting thermal energy into mechanical energy?

Turbine Signup and view all the answers

What is a characteristic of air as it passes through the compressor section of a gas turbine?

Air is compressed to a smaller volume at high pressure. Signup and view all the answers

What is the main function of the combustion chamber in a gas turbine?

To inject fuel into the air stream. Signup and view all the answers

How does the design of reciprocating engines typically affect their weight compared to gas turbines?

They are heavier due to many moving parts and design required for vibrations. Signup and view all the answers

What happens to the velocity of the air during the expansion process in the turbine?

The velocity increases as the air expands. Signup and view all the answers

In a gas turbine engine, which phase occurs immediately after combustion?

Energy extraction Signup and view all the answers

What is the engine pressure ratio (EPR) when turbine discharge pressure is 28.52 psia and compressor inlet pressure is 14.7 psia?

1.94 Signup and view all the answers

Which station numbers does the Pratt & Whitney Company use to identify the engine pressure ratio tap-off points in dual-spool engines?

2 and 4.95 Signup and view all the answers

When an aeroplane is flying at 375 miles per hour, each pound of thrust equates to how many horsepower?

1 Signup and view all the answers

If the speed of the aeroplane is doubled, what happens to the horsepower produced by each pound of thrust?

It is doubled Signup and view all the answers

What is the static thrust power (ESHP) formula component associated with the speed of the aircraft?

Fn Signup and view all the answers

In the context of thrust power, which of the following is NOT a unit of measurement for power?

Newton Signup and view all the answers

How is the ESHP adjusted when the thrust produced by the propeller is considered?

It accounts for thrust in pounds and speed Signup and view all the answers

Which equation represents the relationship between thrust and speed for computing power in jet propulsion?

Power = Thrust x Velocity Signup and view all the answers

Study Notes

15.1 Fundamentals

Physics is fundamental to understanding gas turbine engines.
Force is the capacity to do work. Work is done when a force moves an object through distance. Acceleration is change in velocity over time.
Thrust is proportional to both mass and acceleration.
Mass is the amount of matter in an object.
Force is a vector having both magnitude and direction.
Work is the transfer of energy. Kinetic energy is energy of motion. Potential energy is energy due to position or condition.
Power is the rate at which work is done.
Units of measurement: Force (N), Pressure (N/m²), Area (m²), Work (Joules), Distance (m), Time (s), Power(Watts).

15.2 Engine Performance

Thrust is a measure of the output of a turbojet or turbofan engine, not appropriate to use horsepower.
Momentum is the impulse imparted to the air, fuel and combustion products flowing through, either adding to or subtracting from the total.
Net thrust considers change in momentum of air/fuel and pressure difference at nozzle (exit).
Gross thrust considers nozzle pressure, exhaust momentum.
Thrust is influenced by factors such as altitude, airspeed and temperature affecting the flow of air through the engine.
Factors affecting thrust include mass airflow, exhaust nozzle jet velocity, and airspeed.

15.3 Inlet

Air inlet ducts direct air into the engine.
Subsonic and supersonic inlets have different designs.
Ice and debris protection is crucial for inlets.

15.4 Compressors

Compressors increase air pressure.
Types include centrifugal and axial flow compressors.
Compressor design features include guide vanes, stator vanes and converging airflow path.
Axial-flow compressors are categorized by single spool, dual spool, and triple spool.

15.5 Combustion Section

Principles of operation: Gas turbine combustion principles (how power is created).
Multiple-can, Can-Annular, Annular, Reverse-Flow annular combustors.

15.6 Turbine Section

Turbine elements, design and construction, and failure analysis.
Materials, Nozzle Guide Vanes, Turbine Discs and Compressor-Turbine Matching are key elements in turbine section components.

15.7 Exhaust

Turbine engine exhaust and its associated noise suppressors and thrust reversers.

Types of Gas Turbine Engines

Reciprocating engines have limitations in power, weight and maintenance compared to gas turbines. Gas turbines have a higher efficiency and fewer moving parts.
Ramjet, pulse jet, turbojet, turboprop and turbofan engines.
Ramjet and pulse jet engines are simple, but limited in speed capability.

Brayton Cycle

The Brayton cycle describes the thermodynamic cycle of a gas turbine engine.
Constant pressure cycle. Similar events occur at different times & locations from the constant volume Otto cycle.
Air enters the compressor, is compressed, then heated, then passes through a turbine, and finally to the nozzle.
Flow of air is from inlet to compressor, then to combustion chamber, then to turbine and finally to exhaust.

Turbine Engine Terms and Definitions

The engine is divided into "cold section" and "hot section".
Stations are designated numerically to enable accurate identification.

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Description

Explore key concepts in gas turbine engines, including the principles of physics that apply to their operation. This quiz covers important topics such as force, work, thrust, and energy types, alongside their relevant units of measurement.