- temperatures up to about 1200 to1800 F. depending on the alloying elements - good high temperature strength typical use–turbine wheels,turbine blades, shafts, combustion liners •Hot section parts

MOD 1-2 Flashcards by Carolina Herrera

Jet propulsion can be defined as

a method of propulsion produced when a mass of air is given acceleration

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Sir Isaac Newton second law of motion

Force = mass x accelaration

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Leonardo De vinchi create the first example of a reaction turbine and it called

chimnay jack

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Sir Frank Little is consider the father of

of the jet engine, first flight Gloster E28

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first German flight of a jet propeller

HE178-1100 Lbs Trust 400 m/h

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Turbine Engine classifications

Turbo jet Turbo fan Turbo prop Turbo shaft

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what is TSFC

Thrust Specific Fuel Consumption, how much fuel is consume to produce thrust

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Turbo Jet characteristics

Low Thrust High TSFC at low altitudes and lower speeds long take off roll -disadvantage small frontal area lightest specific weight (weight for power produce) takes advantage of high ram pressure

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Turbo Fan Characteristics

-increase thrust at speeds for short take off , but not falling off at higher speeds -weight lighter than TP heavier than TJ -medium TSFC -medium frontal area -reduce noise from turbo jet

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Turbo prop characteristics

-high propulsive efficiency at low speeds -more complicated and heavier than TF and TJ -lowest TSFC -large frontal area -efficient reverse system (180 degree)

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what is propulsion efficiency

is an indication of how much energy is being wasted or lost

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turbo shaft

similar to turbo prop out to a transition or gearbox can not get a propulsive efficiency

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3 Mayor sub classification of a gas turbine

axial centrifugal axial-centrifugal

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why turbo shaft or turbo prop required gearbox

to reduce the speed of the blades or propeller not allowing get to the speed of sound

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basic components of a turbine

air inlet, compressor, diffuser, combustors, turbine, tail pipe and jet nozzle

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common engine identification

1-atmosphere

2-face compressor

3-discharge freom final compresor

4-combustion discharge

5-turbine section

6-turbine discharge

7- exhaust

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what is creep strenght

the ability of a metal to resist slow deformation from strees of time, temp, load

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engine cycle definition

VARIES BETWEEN MANUFACTURES

May be a start and RPM exceeding 80% N2

Maintenance run for leak check may not be counted as a cycle if RPM is kept below 80% N2

Some may only count a cycle if the wheels leave the

ground ( can do a full power run and not count a cycle

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What is Yield Strength

the point when a metal takes on a permanent set due to application of a load

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what is Rupture Strength

The point at which a metal will fail due to continual loading for long periods of time

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Aluminum alloys carachteristics

Temperatures up to about 500

good strength to weight ratios

typical use-inlet ducts, centrifugal compressor components, accessory drive cases

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Titanium alloys

temperatures up to about 1000 F

high strength, low density

•

typical use

centrifugal flow compressors, axial flow

compressor rotors and blades

ignition point is lower than melting point

does not dissipate heat well (low density)

Cold section parts

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Steel alloys characteristics

temperatures up to about 1000 to1200 depending on the alloying elements

-low cost (relative to cost of other materials) ease of fabrication and machining

•typical use

compressor stators, engine structural members,compressor shafts, gears, cases

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Nickel base alloy

temperatures up to about 1200 to1800 F. depending on the alloying elements
good high temperature strength

typical use–turbine wheels,turbine blades, shafts, combustion

liners

•Hot section parts

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Cobalt base alloy

withstands high temperatures * melting point–2700 F * expensive

4 types cooling

Convection -heat disipades to the air Inpingment-bleed air blown onto a hot part Film-bleed air through holes transpiration cooling -mesh

What is N1 N2 Ng Nf

N1 -Rotational RPM low compressor and turbine ) N2-rotation RPM high pressure compresor and turbine Ng -RPM of the gas producer Nf -RPM of free turbine

what is ITT TOT TIT Tt15

ITT-Inlet turbine temp TOT- turbine outlet temp TIT-turbine inlet temp Tt15 -Turbine temp station 5

N1 and N2 is a measurment of what

rotational speed in % RPM

what is primary creep,secundary creep and tetiary creep

primary is a significant change that happens in a short period of time secundary is the slow deformation of the blade over a long period of time, tertery creep is a fast deterioration of the blade.

three prymary indications necessary for a gas turbine engine are

RPM TEMPERATURE TORQUE OR THRUST

Creep strenght is ussually referred to in terms of ?

time,temp,load

Brayton cycle is also known as ?

constant pressure cycle because the pressure in the combustion section remains the same

difference betwen potencial energy and kenetic energy

potencial energy relates to the mass, gravity and height and kenetic energy is in motion not in rest

difference between heat and temp

heat is the transfer of thermal energy and temp is the average kenetic energy

potencial energy can also reffered as ?

static pressure

kenetic energy canbe referred to as ?

dynamic pressure

according to bernoulis law, when fluid flows thruogh a divergent duct does the pressure increase or decrease

velocity decrease so pressure increase

according to bernoulis law, when fluid flows thruogh a convergent duct does the pressure increase or decrease

velocity increase so pressure decrease

in the Bryton cycle what section of the engine represents by point B to C

Combustion

in the Bryton cycle what section of the engine represents by point D to E

exhaust -turbine trust for propulsion (turbo jet and turbo fan)

in the Bryton cycle what section of the engine represents by point D to F

exhaust -turbine trust for propulsion (turbo prop and turbo shaft)

in the Bryton cycle what section of the engine represents by point C to D

Turbine

in the Bryton cycle what section of the engine represents by point F to G

represents the energy left in the gases after the last turbine (in a turbo prop).

in the Bryton cycle what section of the engine represents by point A to B

Compresor

on the engine map why does the pressure increase trought the convergent duct instead of decrease ?

because the divergent inside of the convergent duct

where is the highest total pressure in the engine

last part of the compressor stage

where is the lowest velocity ?

getting into the combustion section

why the specific heat of air under constant pressure, a higher BTU value that the specific heat air under constant volume

because the volume increase in constant pressure and requires more energy

performance limitation

RPM turbine temp torque or thrust

total energy= to?

potencial energy +kenetic energy or static pressure + velocity

total pressure = to?

static pressure +dynamic pressure

The area of a \_\_\_\_\_\_\_\_\_\_\_\_decreases in the direction of fluid is flowing

convergent duct nozzle

The area of a \_\_\_\_\_\_\_\_\_\_\_\_\_\_increases in the direction of fluid is flowin

divergent duct (diffuser )

what is thermal efficency ?

A ratio of the engines energy output (thrust or torque), to the fuel energy input

horsepower is equivalent to ?

1 HP = 33000 ft/min 1 HP = 550 ft/sec

amount of energy required to raise 1 # of air under constant volume ?

0.1715 BTU

amount of energy required to raise 1 # of air under constant pressure ?

0.24 BTU

specific heat formula what are the constants and what is Wa, delta T and |Cp ?

In the airflow through a convergent or divergent duct, the potential energy can also be referred to as \_\_\_\_\_\_\_\_\_\_.

static pressure

. In the airflow through a convergent or divergent duct, the kinetic energy can also be referred to as \_\_\_\_\_\_\_\_\_\_.

dynamic pressure

According to Bernoulli’s Principle, when a fluid flows through a convergent duct, does the total pressure increase, decrease or remain the same?

decrease

According to Bernoulli’s Principle, when a fluid flows through a divergent/diffusing duct, does the total pressure increase, decrease or remain the same?

increase

According to the General Gas Law, does “V” represent velocity or volume?

volume

According to the General Gas Law, if “V” is held constant and “P” increases, does “T” increase or decrease?

increase

MOD 1-2 Flashcards

(65 cards)