Gas Turbine Stator Vanes and Rotor Blades Quiz

Consist of a multi-bladed ducted propeller driven by a gas turbine engine.

Uses a relatively large diameter ducted fan that produces thrust and provides intake air to the compressor.

Developed to provide a compromise between the best features of the turbojet and the turboprop.

This arrangement of a turbofan is rarely used since it cannot contribute to air compression at the inlet.

In a dual compressor forward fan engine, the fan is an integral part of the __________ compressor.

_________ drives only the fan while the intermediate and forward turbines drive a forward, low pressure compressor and a rear, high pressure compressor, respectively

The fans of turbofan engines produce between _______ of the total thrust.

Refers to the ratio of incoming air that bypasses the core to the amount of air that passes through the engine core.

Bypass ratio is 1:1

Bypass ratio is 2:1 or 3:1

What is the ratio of a High bypass

Is a comparison of the thrust produced by the fan to the thrust produced by the engine core exhaust

Offers a higher propulsive efficiency and better fuel economy

Is the ratio of air pressure leaving the fan to the air pressure entering the fan.

Fan pressure ratio on a typical low bypass fan is approximately

High bypass fans fan pressure

Utilize titanium, lightweight stainless stell, and composite materials to surpass the fuel economy by more than 15 percent.

Designers have achieved a 30:1 bypass ratio by incorporating single or dual propellers with composite blades that are 12 to 15 feet in diameter.

5 major sections of a gas turbine engine

Cold Section of GTE

Hot section of GTE

is designed to conduct incoming air to the compressor with a minimum energy loss resulting from drag or ram pressure loss; that is, the flow of air into the compressor should be free of turbulence to achieve maximum operating efficiency.

To recover as much of the total pressure of the free airstream as possible and deliver this pressure to the compressor.

the air inlet duct is located directly in front of the compressor and is mounted to the engine.

Inlets are positioned near the wing root area.

an air inlet of this type allows the aircraft manufacturer to build a more aerodynamic aircraft, the increased length of the inlet does introduce some inefficiencies.

air inlet consists of a fixed geometry duct whose diameter progressively increases from front to back.

Air entering the compressor on a turbine engine must flow slower than the speed of sound.

This divergent shape works like a venturi in that as the intake air spreads out, its velocity _________ and its pressure __________.

When air traveling at supersonic speeds flows through a convergent duct, its velocity _________ and pressure ________.

When air traveling at supersonic speeds flows through a divergent duct, its velocity _________ and pressure ________.

t is designed specifically for obtaining very high aerodynamic efficiency when stationary or in slow flight.

develop the majority of their thrust with propeller rather than jet propulsion

typically smaller than those used on turbojet or turbofan engines.

is a top priority among turbine engine operators and manufacturers

This vortex can become strong enough to lift water and debris such as sand, small stones, or small hardware from the ground and direct it into the engine.  To help alleviate this problem, what kind of device is installed?

The component that forces air into the engine is the

This ratio is the outlet pressure divided by the inlet pressure.

To be effective, a modern compressor must increase the intake air pressure

is taken from any of the various pressure stages of the compressor

Types of Compressors

Types of design of blade attachment

Centrifugal-flow compressor consists of

Sometimes called a radial outflow compressor

One of the earliest compressor designs and is still used today in some smaller engines and auxiliary power units

is usually made from forged aluminum alloy, heat treated, machined, and smoothed for minimum flow restriction and turbulence.

consists of a forged disk with integral blades, fastened by a splined coupling to a common power shaft.

two impellers are mounted back-to-back

allows a higher mass airflow than that of a similar sized single-stage, single-sided impeller

the air is expelled into a divergent duct called a

acts as a divergent duct where the air spreads out, slows down, and increases in static pressure.

diverts the flow of air from the diffuser, which is an integral part of the manifold, into the combustion chambers.

The task of this compressor is to raise air pressure rather than air velocity

are stationary blades located between each row of rotating blades and act as diffusers at each stage, decreasing air velocity and raising pressure.

The set of stator vanes immediately in front of the first stage rotor blades are called

These vanes direct the airflow into the first stage rotor blades at the best angle while imparting a swirling motion in the direction of engine rotation.

automatically reposition themselves to maintain proper airflow through the engine under varying operating conditions

These vanes straighten the airflow and eliminate any swirling motion or turbulence

Compressor blade tips are reduced in thickness by cut-outs, referred to as

high pressure, high speed, or N2 compressor and is typically driven by a single stage high-pressure turbine at the front of the turbine section

called the low pressure, low speed, or N1 compressor

On many turbofan engines, the compressor section is divided into three sections and is referred to as a

In triple-spool compressor arrangement ________is referred to as the low speed, or N1 compressor

next in line is called the intermediate, or N2 compressor,

is the high pressure, or N3 compressor.

were developed to combine the best features of centrifugal and axial compressors and eliminate some of their disadvantages.

occur when the compressor blades' angle of attack exceeds the critical angle of attack.

cause air flowing in the compressor to slow down and stagnate, sometimes reversing direction.

can significantly impair engine performance, cause loss of power, and can damage the engine

is typically located directly between the compressor diffuser and turbine section.

for gas turbine engines is the high-energy capacitor discharge system, consisting of an exciter unit, two high-tension cables, and two spark igniters.

Ignition system produces how many sparks

accomplishes the important task of draining the unburned fuel after engine shutdown.

Approximately__________ of the incoming air is designated as primary

Approximately __________ percent of the incoming air is designated as secondary

Two types of Flame Out

usually occurs at high altitude where low engine speeds and low fuel pressure form a weak flame that can die out in a normal airflow

occurs during rapid engine acceleration when an overly-rich mixture causes the fuel temperature to drop below the combustion temperature or when there is insufficient airflow to support combustion.

Types of Combustion Chambers

consists of a series of individual combustor cans which act as individual burner units

This type of combustion chamber is well suited to centrifugal compressor engines

consists of a housing and perforated inner liner, or basket.