COMMON CORE1 Flashcards
Matter
anything that occupies space, classified as either an element or a compound
Solid matter
retains its original shape and volume when moved from one container to another
Liquid matter
will retain volume but not shape after being moved
Gas matter
will take on the shape and volume of any container
Volume
amount of space that an object or substance occupies
Mass
amount of matter that a body contains
Weight
a measurement of force caused by gravity on a unit of the earth
Gravity
a force that attracts objects toward the center of earth
Density
amount or quantity of mass per unit volume
Foce
total pressure acting on an object
Pressure
is force per unit of area measured in pounds per square inch (PSI)
Static Pressure
pressure in a confined space or not causing motion
Impact Pressure
pressure caused by motion
Relative Pressure
one pressure in relation to another
Absolute Pressure
the sum of atmospheric pressure and system pressure starting from the theoretical vacuum
Pascal’s Law
states that pressure applied to an enclosed or confined fluid is transmitted equally in all directions without loss, and acts with equal force on all surfaces
Bernoulli’s Principle
States that whenever a stream of any fluid, has its velocity increased at a given point, the pressure of the stream at that point is less than the rest of the stream
Convergent Venturi Tube
will increase velocity and decrease pressure
Divergent Venturi Tube
will decrease velocity and increase pressure
Boyle’s Law
states that the volume of a given mass of gas varies inversely with pressure when the temperature remains constant
Charles’ Law
states that if the volume of a confined gas is constant, the pressure is directly proportional to the absolute temperature, or if the pressure is unchanged, the volume is directly proportional to the absolute temperature
Newton’s First Law
law of inertia
Newton’s Second Law
low of force and acceleration
Newton’s Third Law
law of interaction
Heat
a form of energy produced by the motion of molecules and is known as kinetic energy
Measurements of Heat
British Thermal Unit (BTU) and Calorie
British Thermal Unit(BTU)
is the amount of heat required to raise the temperature of one pint of water one degree on the Fahrenheit scale
Calorie
is the amount of heat required to raise the temperature of one gram of water one degree on the Celsius scale
Methods of Heat Transfer
Conduction, Convection, Radiation
Conduction
is the transmission of heat from molecule to molecule
Convection
is the transfer of heat by means of currents in a fluid caused by uneven heating
Radiation
is the transfer of heat by means of high-speed particles of energy
Temperature
is the intensity of hotness or coldness of a mass measured in degrees
Measurements of Temperature
Fahrenheit, Celsius, Kelvin, Rankine
Fahrenheit scale
32 degrees freezing point of water and 212 degrees as boiling point
Celsius scale
0 degrees freezing point of water and 100 degrees boiling point
Kelvin or Rankine
absolute temperature is measured from absolute zero on these scales
Atmosphere
known as the whole mass of air surrounding the earth, contains 78%nitrogen 21%oxygen 1%inertia
Atmospheric Pressure
is a column of air with a one square inch base area and a height equal to the height of the atmosphere will weigh 14.7 PSI. or 29.92inches of mercury on the barometic scale
Troposphere
the lower limit that contains weather conditions
Stratosphere
has an average temperature of -69.7 degrees F, provides the best conditions for jet aircraft flight.
Mesosphere
has conditions that do not allow for gas turbine engine operation due to lack of oxygen
Thermophere
is the electronically charged protection layer for the earth
Work is supplied to the machine
INPUT WORK
Work is exerted against friction
ENERGY IS EXPENDED
Output work is done by the machine
USEFUL WORK
The efficiency of a machine is measured by
the ratio of work output divided by work input
Two mechanical advantage categories
Lever and Inclined Plane
Flight controls, landing gear, engine control linkage, accessory gears, transmissions, and gas turbine engine are examples of:
Inclined Plane mechanical advantages
Hydraulics:
science that deals with the study of liquids in motion
Law that states pressure applied to an enclosed or confined fluid is transmitted equally, in all directions without loss
Pascal’s Law
What is the purpose of Hydraulics
to move mechanical components accurately and safely with ease
Components of the Hydromechanical System
CRAP FSTR Check valve Relief valve Actuating unit Pump Filter Selector valve Tubing Reservoir
Reservoir
contains the supply of fluid used by the system
Filter
filters out contamination
Pump
creates the flow of fluid
Relief valve
relieves excessive system pressure
Selector valve
directs the flow of fluid
Actuating unit
converts fluid pressure to useful work(mechanical motion)
Tubing
transports the fluid throughout the system
Check valve
permits fluid to flow in one direction only
Greatest Maintenance hazard associated with hydraulic systems
CONTAMINATION
Two classes of contamination
Abrasive and non abrasive
Origins of Contaminants
Originally contained in the system
Outside sources
Created within during operation
Foreign liquids
Development of Gas Turbines history:
Hero of Alexandria, first jet machine “Aelipile” 150 B.C.
Giovanni Branca, 1629 turbine powered stamp mill
Ferdinand Verbiest, 1678 first steam jet horseless carriage
Ram Jet:
an air breathing engine that compresses the incoming ram air pressure, adds heat energy, and converts heat energy to velocity to produce thrust. must have speed of 250 mph to ignite and sustain ops
Pulsejet:
used as German robot bomb, or V-1 weapon, in 1941
Turbojet:
first U.S. gas turbine built in 1902 at Cornell University. Jet flight propelled 27 AUG 1939 by Henkel Aircraft company
Power:
the rate of doing work or the rate of expending energy
Motion:
the act or process of changing place or position
Velocity:
the rate of change of distance with respect to time in a given direction
Constant Velocity:
the distance traveled per unit of time remains the same
Acceleration:
the rate of change of velocity
Energy:
the ability to do work or bring about changes in matter
Inertia
property of a body that tends to resist a change in its state of rest or motion
Jet Propulsion:
Propelling force generated in the direction opposite to the flow of a gas under pressure, which is escaping through on opening called a jet nozzel
Standard Day:
Barometric pressure: 29.92 inches of mercury(14.7PSI @ sea level)
Humidity: 0%
Temperature: 59 degrees F
Wind Velocity: Zero
Brayton Cycle
the name given to the thermodynamic cycle of a gas turbine engine to produce thrust
4 continuous events in the Brayton Cycle
Intake Compression Combustion Exhaust
Principles of Thrust
thrust is the driving force produced by a gas turbine engine, it is measured in pounds and obtained by accelerating a quantity of mass and expelling it rearward through a jet nozzle.
Static Thrust
thrust produced when the aircraft or engine has no forward motion, all gas turbines are rated in static thrust under standard day condidtions
Net Thrust
thrust available to power the aircraft in flight
RPM
revolutions per minute, this affects thrust more than any other variable.
increase RPM
increase mass airflow and increase thrust
decrease RPM
decrease mass airflow and decrease thrust
Atmospheric Variables
OAT(outside air temperature), Barometric Pressure, Humidity.
OAT(outside air temperature)
increase OAT will reduce density and decrease thrust. decrease OAT will increase density and increase thrust
Barometric Pressure
will decrease with any increase in altitude from sea level, and engine efficiency gradually declines. decreasing density and thrust
Humidity
the amount of water vapor present in the air at any given time. humidity displaces air molecules, lowering air density. it has the least effect on thrust of all variables
An increase in Humidity will
decrease density and decrease thrust
A decrease in humidity will
increase density and increase thrust
Turbojet
uses only the thrust developed within the the engine to produce its force, basic engine used in other designs.
Turbofan
is a turbojet engine with a front fan
Turboshaft
use extra stages of turbine wheels to drive reduction gearing to drive a rotating airfoil
Turboprops
use extra stages of turbine wheels to drive reduction gearing to drive a propeller
2 and 3 digit system prefix
PREFIX
X-experimental
Y-Restricted
No Prefix- testing is complete
2 and 3 digit system part one
TYPE
J - Turbojet
TF - Turbofan (3digit is F only)
T - Turboshaft and Turboprop
2 digit system: engine designation numbers
starting at 30 even numbers are Navy
starting at 31 odd numbers are Airforce
3 digit system: engine designation numbers and Model Numbers
100 Air Force, 400 Navy, 700 Army
2 digit system part three: Model Numbers(what branch uses it)
starting with 1 odd numbers are Air Force
starting with 2 even numbers are Navy
2 and 3 digit system: suffix
used only when minor modifications are incorporated, represented by one letter(THE SUFFIX IS DROPPED WHEN THE NEXT MAJOR MOD IS INCORPORATED)
Engine Section Breakdown: Front Frame
LOCATION: mounted to the front of the compressor.
PURPOSE: Welded steel ring forms the compressor front frames. Receives air from the aircraft air inlet and delivers it to the compressor.
COMPONENTS: Inlet Guide Vanes
AIRFLOW: Pre-swirls to prevent shock
Engine Section Breakdown: Compressor
LOCATION: Between the front frame and the combustion section
PURPOSE: Supplies compressed air sufficient to meet the requirements of the combustion section and supplies bleed air
COMPONENTS: Casing, Rotors, Stators, Exit Guide Vanes, Diffuser
AIRFLOW: Pressure increases, Temperature increases, Velocity stabilizes
Engine Section Breakdown: Combustion
LOCATION: Between the compressor section and the turbine section
PURPOSE: Burns the fuel air mixture adding heat energy to the mass air flow from the compressor to drive the turbine which drives the compressor and accessories
COMPONENTS: Casing, Combustion Chamber, Ignitors, Fuel Nozzles, Fuel Drain
Engine Section Breakdown: Turbine
LOCATION: Between the combustion section and the exhaust section
PURPOSE: Extract energy from the expanding gases from the combust-ion section & convert them to shaft horsepower to drive the compressor and accessories
COMPONENTS: Casing, Turbine Nozzle, Turbine Blades, Disk, Shaft
AIRFLOW: Pressure decreases, Temperature decreases, Velocity increases
Engine Section Breakdown: Exhaust
LOCATION: Aft of the turbine section
PURPOSE: Straighten & directs the hot gasses rearward creates a solid jet stream imparts a final boost in velocity
COMPONENTS: Casing, Inner, Cone, Struts, Tailpipe, Exhaust Nozzle
AIRFLOW: Pressure decreases, Temperature decreases, Velocity increases
Engine Section Breakdown: Accessory
LOCATION: Front(near bottom) of compressor
PURPOSE: To change compressor rotor speeds to suitable drive speeds for engine accessories
COMPONENTS: Power takeoff shaft, Accessory gearbox
AIRFLOW: N/A
Vanes
accommodate tubes to carry lubricating oil to and from the front main bearing
Axial flow compressor
compresses the air in a direction that is parallel to the axis of the engine, has alternating series of airfoils(rotor blades) and stationary airfoils(stator vanes)
Types of Axial Flow Compressors
Single Rotor(Solid-Spool) and Dual Rotor(Split-Spool)
Types of Fuel Nozzles
Duplex(most widely used due to good spray) and Simplex(spray pattern limited in use)
Types of Combustion Chambers
Annular(uses limited space to permit better mixing of fuel and air for more efficient combustion and Can-annular(individual chambers are places side by side to form a circle of cans inside a single casing)
Turbine Blades:
extract the energy from the expanding gases and transmit it to the rotor disk….Impulse type- low thrust engines. Reaction type- medium thrust engines. Impulse type- high thrust engines
IGVs(Inlet Guide Vanes)
are hollow to allow for hot air from the engine to ciculate through the vanes and Lube tubes to carry Lube to the front main bearing
COMPRESSOR SECTION SUPPLIES BLEED AIR FOR:
Heating and air conditioning.
Cooling engine cavities
Anti icing
Cabin, Oil seal, Fuel cells and fuel transfer Pressurization
Axial flow compressor:
compresses the air in a direction that is parallel to the axis of the engine
Stator Vanes:
stationary airfoils
Stator Assembly:
stationary vanes dove-tailed into split rings and mounted to the compressor casting
Rotor Assembly:
Compressor Shaft, Disks, Blades.
Compressor Blades:
are attached to the compressor disks by dovetail, bulb, or fir tree root. They are locked into place by Peening, Pins, Locking Wires, or Keys
Exit Guide Vanes:
stationary vanes with fixed vane angle and may consist of one or more rows, which straighten air to eliminate turbulence
Diffuser
forms the compressor rear frame.
highest point of pressure, and divergent in design which develops a pressure wall to prevent reverse flow.
Single Rotor axial flow compressor
have all rotating blades on one rotor
Dual Rotor axial flow compressor
Two rotors(spools) in one engine
Fuel Nozzles:
Duplex- most widely used due to good spay pattern
Simplex- limited use
Combustion chambers:
Annular– uses limited space to permit better mixing of fuel and air for more efficient combustion
Can-Annular– individual chambers are placed side by side to form a circle of cans inside a single casing
chamber air flow
25% to support combustion 75% for cooling and flame control
Turbine energy use is determined by:
compressor size, # of engine driven accessories, gearboxes to drive propellers, rotary airfoils driven by shafts.
Nozzle Assemblies(same of compression stator vanes)
convert heat and pressure into velocity, direct gases to the turbine rotor blades at the most efficient angle.
Turbine rotor assembly:
to convert velocity into mechanical (shaft horsepower) energy
Turbine Blades:
impulse, reaction, impulse-reaction.
low, medium, high
