Turbo

Turbocharger basics

1. What is the air charging
To increase the output efficiency of any engine we have to urn more fuel and make bigger explosion in every cycle and we have two option of this :
One way to add power is to build a bigger engine , but bigger engines , which have more weight, cost and maintain aren\t always better.
Another way to add power is to make a normal-sized enginemore efficent . we can achieve that by forcing more air into the combustion chamber . more air means that more fuel can be added , and more that means a bigger explosion and greater power and that can be done by a help of supercharger
2.What is the turbocharger
A turbocharger is a device fitted to internal combustion engines to increase power. In a normal car engine the amount of power theengine produces depends on how much fuel is being burnt in the cylinders. In a non-turbocharged engine a mixture of air and fuel is drawn into the engine as the piston moves down in the cylinder. The ideal mixture is 14.7:1 air to fuel (by weight) for gasoline. This is called the stoichiometric ratio. If you add more air to an engine you must add more fuel. And if you are burning more fuel you willgenerate more power.
To increase the amount of air in the engine must use the turbocharger. The turbocharger uses a compressor. The compressor consists of a finned wheel that spins at high speed in a specially shaped housing. Air is drawn into the center of the compressor wheel and accelerated as it is flung to the outside of the wheel .
The compressor wheel must run at very high speeds to giveuseful levels of boost. The compressor wheel is connected to one end of a shaft which runs through the central core of the turbocharger. The shaft usually runs in plain bearings which need constant lubrication.

At the opposite end of the shaft from the compressor is the turbine wheel. The turbine wheel is also contained in housing but in this case hot exhaust gases from the engine are fed infrom the edge of the housing and flow out from the centre of the wheel. The flow of hot gas causes the wheel to accelerate to the very high speeds. Once the gases have passed the turbine wheel they flow through the normal exhaust system of the engine. Because too much boost can actually be damaging to an engine, a way of limiting the turbine wheel speed is often needed. One way of doing this is witha wastegate. The wastegate allows the hot exhaust gases to bypass the turbine wheel.

Fig 2.1

3.Types of supercharging system

3.1 Mechanical Supercharging

A supercharger is an equipment that compresses the air being delivered to an engine, allowing the combustion chamber to be overfilled without enlarging the space.
Mechanical Superchargers take its motion from the cranckshaft via abelt. The higher concentration of oxygen provided by a supercharger is matched with a larger amount of fuel from the fuel injectors thus boosting the power of the engine. supercharger can generate as much as 46 percent additional horsepower but it consume 20 percent of the engine total power output .
Advantages of superchargers:
* Ensures complete combustion of the fuel.
* Increases thetorque produced.
* Increases the power of an engine.

Fig 3.1
3.2 Exhaust gas supercharging (turbocharger)
In this system, the supercharger uses the exhaust gas energy to operate the compressor through an exhaust gas turbine. The turbine and compressor is connected together via a shaft .

Fig 3.2

Low exhaust gas temperature and quantity inaddition to the inertia of the turbocharger delay the pressure buildup; this is called the “turbo-hole”. Using light weight materials, the turbocharger mass has been nowadays considerably reduced.

Fig 3.3
Therefore, turbochargers are actually widely used for passenger cars and commercial vehicles. In order to limit the charge air pressure and to protect the charger parts from being damaged, the...