飞机发动机术语英文解释(A-B)
Acceleration lag --
in the turbine engine, delay between the time instant power is requested
and when power is available. The time it takes the engine to accelerate
and give the required power increase.
Aerodynamic drag --
force which thrust must overcome to move an aircraft forward. Design can
lesson aerodynamic drag through streamlining. Drag increases with
increased speed.
Airbleed actuator --
device that operates the interstage bleed system, to improve compressor
acceleration characteristics by unloading small amounts of compressed
air.
Air density--
total mass of air per given volume, the weight of a given volume of air.
Air is denser at lower altitude, at lower temperature, and lower humidity.
Airfoil profile --
outline of an airfoil section.
Airfoil section --
cross section of an airfoil parallel to a specific reference plane.
Air-fuel ratio --
Ideal mixture of 15 parts of air to 1 part of fuel by weight; the mixture
to be burned in the combustion chamber.
Air inlet --
large, smooth aluminum or magnesium duct at mouth of engine which conducts
air into the compressor with minimum turbulence and restriction.
Aluminum alloy --
any of a variety of alloys formed by combining commercially pure aluminum
with other metals or materials such as copper, silicon, manganese,
magnesium, and zinc. These alloying agents maybe added singly or in
combination to produce a metal with desired characteristics or strength,
heat resistance, corrosion resistance, and the like. Both wrought-and
cast-aluminum alloys are widely used in the manufacture of rotor blades
and aircraft propellers.
Ambient --
condition of atmosphere existing around the engine, such as ambient
pressure or temperature.
Annular combustion chamber --
two-part combustion chamber made up of an annular liner and a housing
assembly. The compressed air goes into a ring-shaped space formed by the
annular liner around the turbine shaft rather than into individual
combustion chambers. The space between the outer liner wall and the
housing assembly allows the flow of cooling air. Used with axial-flow and
dual compressors.
Annular reverse-flow engine --
type of gas turbine engine most commonly used in Army aircraft. Airflow
direction is reversed in the combustion area.
Anti-icing system --
device that supplies hot air under pressure to prevent icing of the inlet
housing areas and inlet guide vanes. Hot scavenged oil is also circulated
through internal passages in the walls and struts.
Army Spectrometric Oil Analysis Program (ASOAP) --
periodic oil analysis for microscopic metal particles. This takes place
at an oil analysis laboratory.
Atmospheric pressure --
barometric pressure exerted by the atmosphere as a result of gravitational
attraction above the point in question.
Atomizer --
nozzle that creates minute particles and accurately shaped spray of fuel
suitable for rapid mixing and combustion.
Axial-flow compressor --
one in which the air is compressed parallel to the axis of the engine.
It is made up of a series of alternating rotor and stator vane stages.
Bending --
combination of tension and compression. The inside curve is under
compression; the outside is under tension.
Bleed system --
device that unloads small amounts of air to relieve pressure.
Boss --
raised rim around a hole; e.g., axle hole in a wheel. Circular projection
on a casting, usually serving as the seat for a bolt head or nut.
Brayton cycle --
constant pressure cycle, with four basic operations which it accomplishes
simultaneously and continuously for an uninterrupted flow of power. The
turbine engine operates on this cycle.
飞机发动机术语英文解释(C)
Camber --
the curvature of an airfoil's surfaces from the chord line. It maybe
positive, negative, or zero.
Can-annular combustion chamber --
one with characteristics of both the annular types. It has an outer shell
and a number of individual cylindrical liners.
Can combustion chamber --
one made up of individual combustion chambers in which the air from the
compressor enters each individual chamber through the adapter.
Center of pressure --
aerodynamic center of an airfoil; the point where all forces act.
Centrifugal axial-flow compressor --
combination of the centrifugal-flow and the axial-flow compressor. It
usually consists of a five-or seven-stage axial-flow compressor and one
centrifugal-flow compressor. Also called the dual compressor.
Centrifugal-flow compressor --
one with an impeller (rotor), stator, and compressor manifold. The rotor
revolves at high speed drawing air into the blades. Centrifugal force
accelerates the air, and it moves through the stator and through the
manifold.
Centrifugal twisting movement --
force that tends to streamline rotating blades with the plane of rotation.
Choked nozzle --
a nozzle whose flow rate has reached the speed of sound.
Chord line --
imaginary line drawn between the leading and trailing edges of an airfoil.
Combustion --
process of burning the fuel-air mixture in a gas turbine engine.
Combustion chamber --
part of a turbine engine in which the propulsive power is developed by
combustion of the injected fuel and the expansive force of the resulting
gases.
Combustion chamber liner --
engine part usually constructed of welded high-nickel steel, subjected
to flame of extremely high temperature. It is behind the compressor and
receives the compressed air which is mixed with fuel and ignited. The
combustor is where the combustion takes place.
Compressibility effects --
the phenomenon encountered at extremely high speeds (near the speed of
sound) when air ceases to flow smoothly over the wings (or blade) and piles
up against the leading edge, causing extreme buffeting and other effects.
Compressor --
that section of an engine that produces an increase in air pressure. It
is made up of rotating and stationary vane assemblies. It is the gas
producer, or it may be thought of as an air pump.
Compressor rotor --
impeller, may be thought of as an air pump. It accelerates the air rearward
into the first stage vane assemblies.
Compressor stall --
separation of the airflow from the suction surface of the freed or rotating
blades of a compressor. Any degree of stall reduces airflow.
Concave --
pressure side of an airfoil.
Conduction --
transfer of heat through material by communication of kinetic energy from
particle to particle rather than by a flow of heated material.
Convergent area --
place where the cross-sectional area of a duct becomes smaller.
Convergent exhaust duct --
duct used on fixed-wing aircraft; formed by tapering toward the rear of
the duct.
Convex --
suction side of an airfoil.
Crossover tube --
duct carrying flame to the individual cylindrical liners of the
can-annular combustion chamber.
飞机发动机术语英文解释(D)
Diffuser --
aft structural member of an engine. It receives high velocity air from
the centrifugal impeller and decreases velocity and increases air
pressure. In the combustor, a diffuser forms a divergent flow path for
the exhaust gases.
Diffusion --
process by which gases intermingle as the result of their spontaneous
movement caused by thermal agitation.
Directional references --
specific definitions of terms referring to gas turbine engines to identify
front and rear, right and left, bottom and top.
Divergent area --
place where air flows from a smaller into a larger area.
Divergent exhaust duct --
used on helicopter. Device to diffuse the exhaust gases rearward and to
eliminate thrust.
Drag parasite --
drag caused by any member or structure which does not contribute to lift,
such as engine cowlings.
Drag profile --
friction resistance produced by a member moving through the air; in simple
terms, the "stickness" of air against the surface of an airfoil.
Dry-cleaning solvent --
cleaning compound that maybe used for all metal parts.
Dry-sump engine --
one in which the oil is stored separate from the engine.
Dual compressor --
see centrifugal-flow, axial-flow compressor.
Duplex nozzle --
dual-orifice channel through which highly atomized and accurately shaped
sprays of fuel go into the combustion chamber.
Dynamic load --
load on an aircraft due to a dynamic force.
飞机发动机术语英文解释(E)
Effective angle of attack --
that part of a given angle of attack that lies between the chord of an
airfoil and a line representing the resultant velocity of the disturber
airflow.
End play --
longitudinal back-and-forth play of a shaft.
Engine airflow path --
route of the airflow through the engine.
Engine oil pressure indicating system --
device that gives continuous readings of engine oil pump pressure in psi.
Engine oil temperature indicating system --
device electrically connected to the 28 VDC system which transmits
temperature readings to the indicator in degrees centigrade.
Engine speed notation --
the capital letter N, which represents the rotational speed of the engine.
When a number is placed after the N (as in "N1"), it indicates a specific
system on the engine.
Engine stations --
specific locations on the engine designating temperature or
pressure-measuring locations. For example, T3 means the third temperature
pickup on the engine.
Engine surge --
result of compressor stall. The complete engine in stall.
Exhaust --
hot gases discharged from the engine through the exhaust diffuser section.
Exhaust diffuser --
section composed of an inner and outer housing, separated by hollow struts
across the exhaust passage. It forms a divergent flow path for the exhaust
gases.
Exhaust gas temperature indicator --
sensitive millivoltmeter calibrated in degree centigrade, activated by
an electrical force generated by its thermocouple.
飞机发动机术语英文解释(F)
Feedback --
relay through the controls of aerodynamic forces exerted on the control
surfaces and felt by the pilot.
Fir tree mount --
manner of attaching the blades to the disk in the turbine rotor assembly.
The root of the blade where it is attached to the disk is shaped like a
fir tree.
Foreign object --
any object such as a tool, piece of equipment, engine part (nut, bolt,
lockwire) that could in any way damage the engine.
Foreign object damage --
commonly called FOD, harm or destruction to the turbine engine caused by
foreign objects sucked into the inlet area of the engine with the required
air.
Forged --
shaped by hammering. Only the malleable metals are worked successfully.
The application of heat increases plasticity.
Free-power turbine engine --
the turbine engine used by the Army. Sixty percent of the energy produced
by combustion is extracted by the gas producer turbine to drive the gas
producer rotor. The rest of the energy is converted to shaft horsepower
to drive the output shaft of the engine.
Frictional loss --
resistance to the relative motion of air flowing along a duct.
Frontal area --
front part of a gas turbine engine, smaller than that of a reciprocating
engine, therefore producing less drag.
Front of engine --
end from which power is extracted. An exception is the T73 engine on the
CH-54, in which the power is extracted at the end where the exhaust gas
is expelled.
Fuel-air ratio --
see air-fuel ratio.
Fuel atomizer --
see atomizer.
Fuel controls --
devices to control fuel flow. They are usually hydromechanical and include
speed governors, servo systems, valves, metering systems, and sensing
pickups.
Fuel divider --
device that meters fuel to the engine nozzles according to a predetermined
schedule of secondary flow versus primary flow.
Fuel nozzle --
device to inject fuel into the combustion chamber in a highly atomized
and accurately shaped spray.
Fuel pressure indicating system --
device that gives continuous readings in psi of fuel pressure in the main
fuel supply line.
飞机发动机术语英文解释(G-I)
Gas producer--
the compressor in a free-power turbine engine.
Gas turbine engine --
aircraft power plant that is adaptable for both airplanes and helicopters.
Gerotor pump --
modified gear-type pump with two moving parts, an inner toothed element
and an outer toothed element. The inner one has one less tooth than the
outer.
Glow plug --
device that consists of a heating element in a short conventional-looking
spark plug.
Ground angle --
angle between the wing chord and the horizontal plane when the airplane
is at rest on the ground.
Heat exchanger --
fuel-oil cooler, to help cool the oil. The exchanger is a cylindrical oil
chamber surrounded by a jacket through which the fuel passes. Heat from
the oil is transferred to the fuel by conduction.
Hot start --
overtemperature during starting.
Hung start --
failure to reach normal idling RPM during starting.
Igniter plugs--
spark plugs which function only during starting and cut out of the circuit
as soon as combustion is self-supporting.
Imbalance --
uneven distribution of weight resulting in rotating parts being out of
balance. Measured in inch-grams or inch-ounces.
Impeller rotor --
rotor in a compressor that revolves at high speed, drawing air into the
blades.
Induced angle of attack --
that part of any given angle of attack in excess of the effective angle
of attack.
Induced drag --
the part of the total dragon an airplane induced by the airflow about the
lifting surfaces.
Inlet guide vanes --
devices positioned by the inlet guide vane actuator pilot valve. They are
located in front of the first compressor rotor, and they control the angle
of incidence of the inlet air, thus ensuring a compressor surge margin.
Inlet housing assembly --
forward structural support of the engine.
飞机发动机术语英文解释(J-N)
Jam acceleration --
rapid movement of the power lever, calling for maximum rate of rotor-speed
increase.
Jetcal analyzer --
device used to check the exhaust gas temperature during periodic
maintenance inspections or when abnormally high or low temperatures are
noted.
Jet propulsion --
propulsion of a body by means of a jet or stream of gas, obtaining all
or most if its thrust by reaction to the ejection of the combustion
products (gas).
Jet silencer --
a device used to reduce and change the lower-frequency sound waves
emitting from the engine's exhaust nozzle, and thus reducing the noise
factor.
Joule --
unit of energy or work used in rating gas turbine ignition systems. A joule
is equal to the amount of energy expended in one second by an electric
current of one ampere through a resistance of one ohm.
Labyrinth seal --
device for preventing leakage of gas on the gas generator shaft in a
turbine. A labyrinth consists of a series of projections on the rotating
element running in close contact with grooves on the stationary element.
Maintenance allocation chart --
chart in a -20 TM that assigns maintenance tasks to the lowest level
capable of doing them, based on experience, skills, tools, and time
available.
Mean aerodynamic chord --
chord of an assumed rectangular airfoil representing the mean chord of
an actual airfoil.
Metal fatigue--
weakening of metal due to microscopic changes in molecular structures
caused by vibration or exposure.
Micron --
one millionth of a meter.
N1 system --
gas producer.
N2 system --
power turbine and shaft.
Nacelle --
an enclosed shelter (cowling) on an aircraft for a power plant.
Nozzle --
channel through which gas is conveyed to the rotor vanes of a turbine.
Its purpose is to convert pressure into velocity.
飞机发动机术语英文解释(O-P)
Orifice --
opening having a closed perimeter through which a fluid may discharge.
It may be open to the atmosphere, or it may be partially or completely
submerged in the discharged fluid.
Otto cycle --
a constant volume cycle, with four distinct operations performed
intermittently. Reciprocating engines operate on this cycle.
Outside air temperature --
commonly abbreviated as OAT, the temperature of the air outside the
engine.
Overspeed --
RPM in excess of design; 100 percent RPM.
Overspeed governor, N2 --
gearbox mounted on engine inlet housing and driven from the power shaft.
Overspeed governor, fuel control --
part of the torquemeter system, an individual pumping unit which, with
the tachometer drive assembly, sets the torquemeter oil pressure.
Overtemperature --
temperature in excess of maximum allowable design temperature at the
turbine exit.
PD 680 --
cleaning solvent for exterior of engine and its attached components.
Planform --
form or shape of an object, as of an airfoil, as seen in plan view or from
above.
Power --
the rate of doing work; work per unit of time.
Power-to-weight ratio --
relationship between power and weight. Turbine engines produce more power
for weight than reciprocating engines.
Power turbine (N2) --
turbine that is free and independent of the gas producer system. It
develops rotational shaft power.
Pressure oil system --
method of supplying oil under pressure to engine parts.
Pressure pumps --
devices to put oil into the system.
Pressurizing and drain dump valve --
device to prevent flow of fuel to the nozzle until enough pressure is built
up in the fuel control. One also drains the fuel manifold at engine
shutdown and traps fuel in the upper portion of the system to keep the
fuel control primed for faster starts.
Primary air --
air that mixes with fuel in the combustion chamber to form a combustible
mixture. The ratio is 15 parts of air to 1 part of fuel.
飞机发动机术语英文解释(R-S)
Radial inflow turbine --
type of turbine made by some manufacturers, not used in any Army aircraft
today, even though it is rugged and simple, relatively inexpensive, and
easy to manufacture. Similar in design and construction to the
centrifugal-flow compressor.
Ram --
the amount of pressure buildup above ambient pressure at the engine's
compressor inlet due to the forward motion of the engine through the air
(initial momentum of the air).
Ram air pressure --
free stream air pressure, provided by the forward motion of the engine,
Ram ratio --
the ratio of ram pressure to ambient pressure.
Ram recovery --
the ability of an engine's air inlet duct to take advantage of ram
pressure.
Rear of engine --
end of engine from which exhaust gas is expelled.
Reverse flow --
change in direction of airflow in the combustion chamber of a gas turbine
engine.
Rotational direction --
direction of movement of the rotating part, determined by viewing the
engine from the rear.
Rotational speed --
speed at which a propeller, rotor, or some other rotating part rotates;
measured in revolutions per minute.
Scavenge oil system --
method of returning oil from the engine to the oil tank for cooling and
reuse.
Scavenger pumps --
those that drain oil from the sumps at various parts of the engine, retur