![Airforce Museum Berlin-Gatow 135](https://upload.wikimedia.org/wikipedia/commons/f/fa/Airforce_Museum_Berlin-Gatow_135.JPG)
An intake (also inlet) is an opening, structure or system through which a fluid is admitted to a space or machine as a consequence of a pressure differential between the outside and the inside. The pressure difference may be generated on the inside by a mechanism, or on the outside by
ram pressure
Ram pressure is a pressure exerted on a body moving through a fluid medium, caused by relative bulk motion of the fluid rather than random thermal motion. It causes a drag force to be exerted on the body. Ram pressure is given in tensor form as
...
or
hydrostatic pressure
Fluid statics or hydrostatics is the branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body "fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an imme ...
. Flow rate through the intake depends on pressure difference, fluid properties, and intake geometry.
Intake refers to an opening, or area, together with its defining edge profile which has an associated entry loss, that captures pipe flow from a
reservoir
A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation.
Reservoirs can be created in a number of ways, including contro ...
or
storage tank
Storage tanks are containers that hold liquids, compressed gases (gas tank; or in U.S.A "pressure vessel", which is not typically labeled or regulated as a storage tank) or mediums used for the short- or long-term storage of heat or cold. The t ...
. Intake refers to the capture area definition and attached ducting to an aircraft
gas turbine engine
A gas turbine, also called a combustion turbine, is a type of continuous flow internal combustion engine. The main parts common to all gas turbine engines form the power-producing part (known as the gas generator or core) and are, in the directi ...
or
ramjet
A ramjet, or athodyd (aero thermodynamic duct), is a form of airbreathing jet engine that uses the forward motion of the engine to produce thrust. Since it produces no thrust when stationary (no ram air) ramjet-powered vehicles require an ass ...
engine and, as such, an intake is followed by a compressor or
combustion chamber
A combustion chamber is part of an internal combustion engine in which the fuel/air mix is burned. For steam engines, the term has also been used for an extension of the firebox which is used to allow a more complete combustion process.
Interna ...
. It may instead be referred to as a
diffuser
Diffuser may refer to:
Aerodynamics
* Diffuser (automotive), a shaped section of a car's underbody which improves the car's aerodynamic properties
* Part of a jet engine air intake, especially when operated at supersonic speeds
* The channel betw ...
. For an automobile engine the components through which the air flows to the engine cylinders, are collectively known as an intake system and may include the inlet port and valve. An intake for a hydroelectric power plant is the capture area in a reservoir which feeds a pressure pipe, or
penstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills.
H ...
, or into an open canal.
Automobile engine intakes
![Mustang-v6-roush-intake](https://upload.wikimedia.org/wikipedia/commons/1/1b/Mustang-v6-roush-intake.jpg)
Early automobile intake systems were simple air inlets connected directly to
carburetor
A carburetor (also spelled carburettor) is a device used by an internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the venturi tube in the main meteri ...
s. The first air filter was implemented on the 1915
Packard
Packard or Packard Motor Car Company was an American luxury automobile company located in Detroit, Michigan. The first Packard automobiles were produced in 1899, and the last Packards were built in South Bend, Indiana in 1958.
One of the "Thr ...
Twin Six
Twins are two offspring produced by the same pregnancy.MedicineNet > Definition of TwinLast Editorial Review: 19 June 2000 Twins can be either ''monozygotic'' ('identical'), meaning that they develop from one zygote, which splits and forms two em ...
.
The modern automobile air intake system has three main parts, an
air filter
A particulate air filter is a device composed of fibrous, or porous materials which removes solid particulates such as dust, pollen, mold, and bacteria from the air. Filters containing an adsorbent or catalyst such as charcoal (carbon) may als ...
,
mass flow sensor
A mass (air) flow sensor (MAF) is a sensor used to determine the mass flow rate of air entering a fuel-injected internal combustion engine.
The air mass information is necessary for the engine control unit (ECU) to balance and deliver the corre ...
, and
throttle body
A throttle is the mechanism by which fluid flow is managed by constriction or obstruction.
An engine's power can be increased or decreased by the restriction of inlet gases (by the use of a throttle), but usually decreased. The term ''throttle'' ...
. Some modern intake systems can be highly complex, and often include specially-designed
intake manifolds to optimally distribute air and air/fuel mixture to each cylinder. Many cars today now include a
silencer to minimize the noise entering the cabin. Silencers impede airflow and create
turbulence
In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow velocity. It is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between ...
which reduce total power, so performance enthusiasts often remove them.
All the above is usually accomplished by flow testing on a
flow bench in the
port
A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Ham ...
design stage. Cars with
turbocharger
In an internal combustion engine, a turbocharger (often called a turbo) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake gas, forcing more air into the engine in order to pro ...
s or
supercharger
In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement.
The current categorisation is that a supercharger is a form of forced induct ...
s which provide pressurized air to the engine usually have highly refined intake systems to improve performance dramatically.
Production cars have specific-length air intakes to cause the air to vibrate and buffet at a specific frequency to assist airflow into the combustion chamber. Aftermarket companies for cars have introduced larger throttle bodies and air filters to decrease restriction of flow at the cost of changing the harmonics of the air intake for a small net increase in power or
torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
.
Aircraft intakes
Aircraft using piston engines use intake systems similar to automobiles.
With the development of
jet engines
A jet engine is a type of reaction engine discharging a fast-moving jet of heated gas (usually air) that generates thrust by jet propulsion. While this broad definition can include rocket, water jet, and hybrid propulsion, the term typicall ...
and the subsequent ability of aircraft to travel at
supersonic
Supersonic speed is the speed of an object that exceeds the speed of sound ( Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level, this speed is approximately . Speeds greater than five times ...
speeds, it was necessary to design inlets to provide the flow required by the engine over a wide operating envelope and to provide air with a high-pressure recovery and low distortion. These designs became more complex as aircraft speeds increased to Mach 3.0 and Mach 3.2, design points for the
XB-70
The North American Aviation XB-70 Valkyrie was the prototype version of the planned B-70 nuclear-armed, deep-penetration supersonic strategic bomber for the United States Air Force Strategic Air Command. Designed in the late 1950s by North Ame ...
and
SR-71
The Lockheed SR-71 "Blackbird" is a Range (aeronautics), long-range, high-altitude, Mach number, Mach 3+ military strategy, strategic reconnaissance aircraft developed and manufactured by the American aerospace company Lockheed Corporati ...
respectively. The inlet is part of the fuselage or part of the nacelle.
Aircraft with a maximum speed greater than about Mach 2 use intakes with variable geometry to achieve good pressure recovery from take-off to maximum speed.
See also
*
Cold air intake
A cold air intake (CAI) is usually an aftermarket assembly of parts used to bring relatively cool air into a car's internal-combustion engine.
Most vehicles manufactured from the mid-1970s until the mid-1990s have thermostatic air intake syste ...
*
Warm air intake
A warm air intake (WAI) also known as a hot air intake (HAI), is a system to decrease the amount of the air going into a car for the purpose of increasing the fuel economy of the internal-combustion engine.
This term is sometimes used erroneousl ...
*
Short ram air intake
A ram-air intake is any intake design which uses the dynamic air pressure created by vehicle motion, or ram pressure, to increase the static air pressure inside of the intake manifold on an internal combustion engine, thus allowing a greater massf ...
*
Ram-air intake
A ram-air intake is any intake design which uses the dynamic air pressure created by vehicle motion, or ram pressure, to increase the static air pressure inside of the intake manifold on an internal combustion engine, thus allowing a greater massf ...
*
Intake ramp
An intake ramp is a rectangular, plate-like device within the air intake of a jet engine, designed to generate a number of shock waves to aid the inlet compression process at supersonic speeds. The ramp sits at an acute angle to deflect the inta ...
*
Inlet manifold
In automotive engineering, an inlet manifold or intake manifold (in American English) is the part of an engine that supplies the fuel/air mixture to the cylinders. The word '' manifold'' comes from the Old English word ''manigfeald'' (from th ...
References
External links
{{Automotive engine , collapsed
Engines