File Name: intake and exhaust system .zip
The word manifold comes from the Old English word manigfeald from the Anglo-Saxon manig [many] and feald [repeatedly] and refers to the multiplying of one pipe into many. The primary function of the intake manifold is to evenly distribute the combustion mixture or just air in a direct injection engine to each intake port in the cylinder head s.
The word manifold comes from the Old English word manigfeald from the Anglo-Saxon manig [many] and feald [repeatedly] and refers to the multiplying of one pipe into many.
The primary function of the intake manifold is to evenly distribute the combustion mixture or just air in a direct injection engine to each intake port in the cylinder head s. Even distribution is important to optimize the efficiency and performance of the engine. It may also serve as a mount for the carburetor, throttle body, fuel injectors and other components of the engine. Due to the downward movement of the pistons and the restriction caused by the throttle valve, in a reciprocating spark ignition piston engine , a partial vacuum lower than atmospheric pressure exists in the intake manifold.
This manifold vacuum can be substantial, and can be used as a source of automobile ancillary power to drive auxiliary systems: power assisted brakes , emission control devices, cruise control , ignition advance, windshield wipers , power windows , ventilation system valves, etc.
This vacuum can also be used to draw any piston blow-by gases from the engine's crankcase. The intake manifold has historically been manufactured from aluminium or cast iron, but use of composite plastic materials is gaining popularity e.
The carburetor or the fuel injectors spray fuel droplets into the air in the manifold. Due to electrostatic forces and condensation from the boundary layer, some of the fuel will form into pools along the walls of the manifold, and due to surface tension of the fuel, small droplets may combine into larger droplets in the airstream.
Both actions are undesirable because they create inconsistencies in the air-fuel ratio. Turbulence in the intake helps to break up fuel droplets, improving the degree of atomization. Better atomization allows for a more complete burn of all the fuel and helps reduce engine knock by enlarging the flame front. To achieve this turbulence it is a common practice to leave the surfaces of the intake and intake ports in the cylinder head rough and unpolished.
Only a certain degree of turbulence is useful in the intake. Once the fuel is sufficiently atomized additional turbulence causes unneeded pressure drops and a drop in engine performance. The design and orientation of the intake manifold is a major factor in the volumetric efficiency of an engine.
Modern intake manifolds usually employ runners , individual tubes extending to each intake port on the cylinder head which emanate from a central volume or "plenum" beneath the carburetor.
The purpose of the runner is to take advantage of the Helmholtz resonance property of air. Air flows at considerable speed through the open valve. When the valve closes, the air that has not yet entered the valve still has a lot of momentum and compresses against the valve, creating a pocket of high pressure.
This high-pressure air begins to equalize with lower-pressure air in the manifold. Due to the air's inertia, the equalization will tend to oscillate: At first the air in the runner will be at a lower pressure than the manifold.
The air in the manifold then tries to equalize back into the runner, and the oscillation repeats. This process occurs at the speed of sound, and in most manifolds travels up and down the runner many times before the valve opens again.
The smaller the cross-sectional area of the runner, the higher the pressure changes on resonance for a given airflow. This aspect of Helmholtz resonance reproduces one result of the Venturi effect.
When the piston accelerates downwards, the pressure at the output of the intake runner is reduced. This low pressure pulse runs to the input end, where it is converted into an over-pressure pulse. This pulse travels back through the runner and rams air through the valve.
The valve then closes. To harness the full power of the Helmholtz resonance effect, the opening of the intake valve must be timed correctly, otherwise the pulse could have a negative effect. This poses a very difficult problem for engines, since valve timing is dynamic and based on engine speed, whereas the pulse timing is static and dependent on the length of the intake runner and the speed of sound. The traditional solution has been to tune the length of the intake runner for a specific engine speed where maximum performance is desired.
However, modern technology has given rise to a number of solutions involving electronically controlled valve timing for example Valvetronic , and dynamic intake geometry see below. In combination with this intake manifold design feature, the exhaust manifold design, as well as the exhaust valve opening time can be so calibrated as to achieve greater evacuation of the cylinder. The exhaust manifolds achieve a vacuum in the cylinder just before the piston reaches top dead center.
In some engines the intake runners are straight for minimal resistance. In most engines, however, the runners have curves, some very convoluted to achieve desired runner length. These turns allow for a more compact manifold, with denser packaging of the whole engine, as a result. In an engine with at least six cylinders the averaged intake flow is nearly constant and the plenum volume can be smaller. To avoid standing waves within the plenum it is made as compact as possible.
The intake runners each use a smaller part of the plenum surface than the inlet, which supplies air to the plenum, for aerodynamic reasons.
Each runner is placed to have nearly the same distance to the main inlet. Runners whose cylinders fire close after each other, are not placed as neighbors. In degree intake manifolds , originally designed for carburetor V8 engines, the two plane, the split plenum intake manifold separates the intake pulses which the manifold experiences by degrees in the firing order. This minimizes interference of one cylinder's pressure waves with those of another, giving better torque from smooth mid-range flow.
Such manifolds may have been originally designed for either two- or four-barrel carburetors, but now are used with both throttle-body and multi-point fuel injection. An example of the latter is the Honda J engine which converts to a single plane manifold around rpm for greater peak flow and horsepower. Older heat riser manifolds with 'wet runners' for carbureted engines used exhaust gas diversion through the intake manifold to provide vaporizing heat.
The amount of exhaust gas flow diversion was controlled by a heat riser valve in the exhaust manifold, and employed a bi-metallic spring which changed tension according to the heat in the manifold.
Today's fuel-injected engines do not require such devices. A variable-length intake manifold VLIM is an internal combustion engine manifold technology. Four common implementations exist. First, two discrete intake runners with different length are employed, and a butterfly valve can close the short path.
Second the intake runners can be bent around a common plenum, and a sliding valve separates them from the plenum with a variable length. Straight high-speed runners can receive plugs, which contain small long runner extensions. The plenum of a 6- or 8-cylinder engine can be parted into halves, with the even firing cylinders in one half and the odd firing cylinders in the other part.
Both sub-plenums and the air intake are connected to an Y sort of main plenum. The air oscillates between both sub-plenums, with a large pressure oscillation there, but a constant pressure at the main plenum. Each runner from a sub plenum to the main plenum can be changed in length. For V engines this can be implemented by parting a single large plenum at high engine speed by means of sliding valves into it when speed is reduced.
As the name implies, VLIM can vary the length of the intake tract in order to optimize power and torque , as well as provide better fuel efficiency. Many automobile manufacturers use similar technology with different names. Another common term for this technology is variable resonance induction system VRIS.
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Main article: Variable-length intake manifold. Vehicles using variable intake geometry. Audi : 2. Ford: The 2. General Motors : 3. An updated version of this technology is employed on the new Mazda Z engine , which is also used by Ford as the Duratec. Engine configurations for internal combustion engines. Two-stroke Four-stroke Five-stroke Six-stroke Two-and four-stroke. W8 W12 W16 W Internal combustion engine. Part of the Automobile series. Engine control unit ECU. Alternator Battery Dynamo Starter motor.
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In this study, an optimum design for intake and exhaust system of a heavy-duty diesel engine was conducted by using the well-known design for six sigma DFSS methodology. As a result of this work, the NOx emission regulation has been successfully satisfied while minimizing the fuel consumption. On the basis of this DFSS work, the design robustness of the engine system was also enhanced. Hence, it is expected that the final design proposal would reduce the variability in brake thermal efficiency BTE that could be caused by the harsh environment and the system aging. Especially, this work has successfully raised the amount of exhaust gas recirculation EGR up to the target level by adopting the venturi tubes in the intake and exhaust lines. In this study, engine cycle simulation technique was employed to assess the effect of the various design parameters and the final design proposal was verified through a real engine test. The current optimum design work has considered four control factors such as the size of turbocharger, the diameter of intake and exhaust venturi pipes, and the efficiency of EGR cooler.
Mechanical Prime Movers pp Cite as. The induction and exhaust systems of diesel and turbine prime movers differ considerably in volume for a given power output, primarily due to the difference in combustion chamber design, and mode of transmitting the power or energy to the moving parts. For an equivalent power output, a simple cycle gas turbine requires more than three times the air intake of an oil diesel engine. In the diesel engine, the air volume ingested is designed to be that which gives the best explosive mixture and power, whereas in the gas turbine engine some of the air is required mainly to control temperature in and around the combustion chamber. Unable to display preview.
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aspirated air intake and exhaust systems on a Diesel Engine. Assessment Criteria. Identify the components in the air intake and exhaust system. Pre-.
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PDF | On Sep 17, , V B Magdas and others published Intake and exhaust pipe optimization for an internal combustion engine | Find, read.