A turbine is a machine used to convert energy generated by moving liquid, gas or air into work. For example, the energy produced by fast flowing water is made to spin a rotating shaft by pushing on the angled blades set around a wheel mounted on the shaft, and this action produces the required work. The generated work helps to drive machines like the propeller of a ship or an airplane or electric generators to produce electricity. The gas or liquid used in a turbine is known as the working medium. The working can be water, steam, gas or air.
The water turbines use water from a waterfall or a dam to drive the turbine. There are two different methods to make the turbine wheels rotate. A water jet may be directed onto the blades. This is called a reaction turbine. In the second method, the turbine wheels are submerged in the following water. These turbines are used at hydroelectric power stations.
For steam turbines to operate, first the steam must be produced by heating water by boilers. The steam enters the turbine at a high pressure. Inside the turbine, the pressure drops and the steam expands. This expansion drives the wheels around. Steam turbines have a series of wheels, mounted on the same shaft. This is because the steam expands gradually as moves through the turbines.
Gas turbines are turned by fast moving jets of gas. These gasses are produced by burning liquid fuels or natural gasses. Air is drawn into the front of the turbine and passed through a compressor. The compressed air is mixed with the fuel and the mixture is ignited in the combustion chamber. This produces, hot, expanding gasses, which drive the turbine wheels. Gas turbines are used to turn the propellers of aircraft and also to propel ships.
Gas turbines are used to jet engines. The hot gasses are sent out at a high speed from the back of the engine. This produces a large amount of thrust that forces the engine to move forward. In jet engines, the purpose of the turbines is to drive the compressor. Turbines are also used in nuclear power stations.