Turbine Engine Operation: Day 1-5

Frank Whittle is known as ______________.

"the father of the gas turbine engine

two ways to heat an inlet:

1. electrical heating elements 2. bleed air

factors that affect thrust(five)

1. engine rpm 2. speed of aircraft 3. air density 4. temperature 5. humidity

advantages of centrifugal compressors (three)

1. high pressure rise per day 2. low weight 3. provides a wide margin of stall free operation

three main parts of a centrifugal flow compressor are:

1. impeller 2. diffuser 3. manifold

cold section includes __________________. (four)

1. inlet 2. compressor 3. diffuser 4. accessory gear box

utilizes the advantage of both the axial and centrifugal compressors (two)

1. ram recovery of the axial compressor 2. high pressure rise per stage of the centrifugal compressor

advantages of axial compressors (three)

1. relatively straight airflow through the engine 2. higher compressor ratios with the use of multiple stages 3. higher peak efficiency due to ram recovery

Types of impellers (three)

1. single entry, single stage 2. single entry, double stage 3. double entry, single stage

cold section components, inlet duct (nacelle) 1. ________________ 2. ________________

1. usually a part of the airframe 2. designed for maximum ram recovery

The typical subsonic aircraft will receive what compression ratio from its flight inlet at cruise airspeed?

1.5:1

Although Germany is credited with the first turbojet-propelled flight in 1939, when did the first British turbojet flight test take place?

1941

exhaust: 1st half- pressure _________, velocity __________. 2nd half- pressure _________, velocity __________.

1st- increases, decreases 2nd-decreases, increases

Which of Newton Laws of Motion can be used to explain turbine jet propulsion

2nd

The Aeolipile required two nozzles exactly 180 degrees apart with a

90 degree angle

When compared to thermal efficiency, what is overall efficiency?

A lesser percentage value

What do the words "variable geometry inlet duct" refer to?

A supersonic flight inlet

Alexander Hero's ____________ was made in 100BC.

Aeolipile

Why does air pressure increase in the engine diffuser section?

Air spreads out radially and slows down, causing a pressure rise

Ram recovery refers to increasing what?

Compression in the flight inlet

What are the three main engine sections?

Compressor, Turbine, Combustor

Supersonic aircraft have an inlet duct with a ________________shape.

Convergent - Divergent

Why is the local speed of sound not affected by changes in atmospheric pressure?

Density and elasticity change proportionally.

What cockpit gauge best indicates the thermal efficiency of an operating engine?

EGT

The term high-bypass turbofan refers to what significant engine ratio?

Fan versus core engine mass airflow ratio

The two turbine design classifications of turboprop and turboshaft engines are:

Fixed turbine, Free Turbine

Newton's Second Law

Force = mass x acceleration

Germans accomplished the first flight of a gas turbine engine in the world in 1936, in the ____________.

HE-178

The three classifications of turbofan engines are:

Low-bypass, High-bypass, Medium-bypass

Who first developed a gas turbine-type accessory (the turbo-supercharger) for an aircraft application?

Moss

low pressure compressor is _________.

N1

intermediate pressure (high pressure if compressor is dual spool) is _________.

N2

The ideal compressor will produce the greatest compression with the least what?

Temperature rise

What is the purpose of the inlet separator?

To remove sand and ice

The two types of thrust-producing turbine engines are:

Turbojet, Turbofan

The two types of torque-producing engines are:

Turboprop, Turboshaft

Who developed the gas turbine engine installed in the HE-178, the first successful prototype turbojet aircraft?

Van Ohain

Bernoulli's Principle states:

Velocity and pressure have an inverse relationship

compressor stall is _____________________.

a distruption of airflow thru the engine caused by an excessively high angle of attack across the blades

A Gas Turbine Engine utilizes

a turbine driven compressor.

Factors such as OAT, altitude, and airspeed all affect thrust because they have the greatest effect on inlet __________________.

air density

Bellmouth inlet ducts are used typically on what type of aircraft?

aircraft that do not exceed 160 MPH. Ex. helicopters, APU's

The four main factors that affect thrust are altitude, ambient temperature, engine r.p.m., and what?

airspeed

Recip engines are limited by two things:

altitude and speed

Ram recovery is the point where pressure inside the inlet equals ___________pressure outside the inlet.

ambient

The main function of inlet guide vanes is to create a change in the ___________of airflow entering the first stage of compression.

angle

The function of a vortex dissipater is to break up suction being created _________________.

at ground level

axial stages first, centrifugal at the ________.

back

A secondary purpose of the compressor is to provide air for internal engine cooling known as engine ____________ air.

bleed

Bellmouth inlet ducts are used 1.____________

by manufactures for engine testing.

Two engine sections for inspection purposes:

cold and hot

a surge is a _______________.

compressor stall

area of pressure increases through the compressor

compressor stator vanes

A low-speed aircraft such as a helicopter that is not designed for ram recovery will often have an inlet duct with a ____________ shape

convergent

divergent duct(diffusers) ____________the velocity and ____________ the pressure thru the duct.

decrease, increase.

turbine: pressure _________, velocity __________, temperature __________.

decreases, decreases, decreases

Commercial airliners and business jets have an inlet (entrance) duct with a _____________ shape.

divergent

Compressor blade roots are normally of the ______________design.

dovetail

Propulsive efficiency is known as the _______________ efficiency of a turbine engine.

external

Turbine engines require a separate supply of oxygen for operations.

false

Dr. Moss helped developed what in order to establish a working turbocharger?

high temperature metals

convergent duct(nozzles) ______________ velocity and ____________the pressure thru the duct.

increase, decrease.

inlet: pressure _________, velocity __________.

increases, decreases

diffuser: pressure _________, velocity __________, temperature __________.

increases, decreases, increases

compressor: pressure _________, velocity __________, temperature __________.

increases, stays the same, increases

Thermal efficiency is known as the _______________efficiency of a turbine engine.

internal

Where in a turbine engine is the pressure the highest?

just before the combustion liners

Net thrust is always _________ than gross thrust. Less/greater

less

Tip speed limits are expressed in values of _______________.

mach numbers

The fan bypass ratio is not a pressure ratio but rather a ratio of two ____________ airflow values.

mass

disadvantages of centrifugal compressors

no advantage gained from ram recovery.

Why is a twist present in axial flow compressor blades and fans?

o provide the trailing edge a uniform axial flow velocity

Gross thrust is calculated when an aircraft is ________________.

on the ground

The primary purpose of the compressor section is to increase air ____________.

pressure

The centrifugal section of a combination compressor is always placed at the _____________.

rear

one ________ and one ________ make up one stage

rotor, stator

The two vector forces that influence velocity and direction of compressor airflow are the inlet effect and the ________________ effect.

rpm

The limits imposed on tip speeds of fan rotors, compressor rotors, and turbine rotors is primarily due to the effect of ________________________on the airfoils.

shock stalling

a compressor attached to a shaft which is driven by its turbine

spool

converts velocity energy into pressure energy

stator

combustion: pressure _________, velocity __________, temperature __________.

stays constant, increases, increases

The local speed of sound depends on only one atmospheric condition, that of ambient _____________.

temperature

Gross thrust is calculated with ___________.

the aircraft static

The Brayton cycle:

the constant pressure cycle of energy transformation used by the turbine engines

Overall efficiency is defined as propulsive efficiency ____________ thermal efficiency.

times

Ramjet turbines can use exit velocity from the turbine engine to serve as a afterburner.

true

Wan Hu made a rocket sled in 1200AD and _____________.

was obliterated