TURBINE ENGINE |
ü Course name: N124
ü Section : CFA
ü Done by : Hazem Al-Moosa
ü ID: H0157824
ü Submitted to Mr: Hedley butterfield
ü Date of submission: 10 / 01/ 2012
Basic turbine engine |
In these days, an airplane without any turbine engines, can be said to be useless.
What is a gas turbine engine? A gas turbine engine is a huge system or machine that
helps the aircraft in 2 things which are: producing thrust for the aircraft in order for the
aircraft to move, and supplying electrical and pneumatic power. Although some people
can use an aircraft as a glider (without a turbine engine), the aircraft would not be as
efficient as with a turbine engine.
History of the turbine engine |
A Greek philosopher and mathematician invented a toy that rotated on top of a boiling tub of water. This caused a reaction effect of hot air or steam that moved several nozzles arranged on a wheel. This works when one understands the Third Law of Motion - every action produces an equal and opposite reaction (equal in force and opposite in direction).
Simple gas turbine theory |
The three main sections of a gas turbine engine are: a compressor, a combustor, and a
power turbine. The gas-turbine operates on the principle of the Brayton cycle, where
compressed air is mixed with fuel, and burned under constant pressure conditions. The
resulting hot gas is allowed to expand through a turbine to achieve work. In a 33%
efficient gas-turbine , approximately 2 / 3 of this work is spent compressing the air ; the
other is available for other work, for example, mechanical drive, and electrical generation.
(James , Harry. Turbine Engines 26 Nov. 2006)
Parts of the gas turbine engine |
In general and in more detailed, there are 5 sections of a gas turbine engine which are:
1. Fan
2. Compressor
3. Combustion or combustor
4. Turbine
5. Exhaust or nozzle
1. FAN
Fan - the fan is the first component in a turbofan. The large spinning fan sucks in large quantities of air. Most blades of the fan are made of titanium. It then speeds this air up and splits it into two parts. One part continues through the core or center of the jet engine, where it is acted upon by the other jet engine components.
The second part "bypasses" the core of the jet engine. It goes through a duct that surrounds the core to the back of the jet engine where it produces much of the force that propels the airplane forward. This cooler air helps to reduce the noise of the jet engine as well as adding thrust to the jet engine.
(A, I.E. Turbine Engines 6 Jan. 2012)
2. COMPRESSOR
Compressor - the compressor is the first component in the jet engine core. The compressor is made up of fans with many blades attached to a shaft. The compressor squeezes the air that enters it into progressively smaller areas, resulting in an increase in the air pressure. This results in an increase in the energy potential of the air. The squashed air is forced into the combustion chamber.
3. COMBUSTION
Combustor - in the combustor the air is mixed with fuel and then ignited. There are as many as 20 nozzles to spray fuel into the airstream. The mixture of air and fuel catches fire. This provides a high temperature, high-energy airflow. The fuel burns with the oxygen in the compressed air, producing hot expanding gases. The inside of the combustor is often made of ceramic material to provide a heat-resistant chamber. The heat can reach 2700°.
4. TURBINE
Turbine - the high-energy airflow coming out of the combustor goes into the turbine, causing the turbine blades to rotate. The turbines are linked by a shaft to turn the blades in the compressor and to spin the intake fan at the front. This rotation takes some energy from the high-energy flow that is used to drive the fan and the compressor. The gases produced in the combustion chamber move through the turbine and spin its blades. The turbines of the jet spin around thousands of times. They are fixed on shafts which have several sets of ball-bearings in between them.
(Navigator , Solar. Jet Engine 9 Jan . 2012)
5. EXHAUST (NOZZLE)
Nozzle - the nozzle is the exhaust duct of the jet engine. This is the jet engine part which actually produces the thrust for the plane. The energy depleted airflow that passed the turbine, in addition to the colder air that bypassed the engine core, produces a force when exiting the nozzle that acts to propel the engine, and therefore the airplane, forward. The combination of the hot air and cold air are expelled and produce an exhaust, which causes a forward thrust. The nozzle may be preceded by a mixer, which combines the high temperature air coming from the jet engine core with the lower temperature air that was bypassed in the fan. The mixer helps to make the jet engine quieter.
Pneumatic and electrical supplies |
Many people think that a turbine engine produces only thrust for the aircraft, and at the same time they think that an aircraft takes the electrical power from the battery. This idea is absolutely wrong. Although we have a battery in an aircraft, this battery is used only for emergency which means that we get the electrical supply power from the generator which is connected to the turbine engine on the aircraft. Around the fan there are small pieces of metal ( metal coils) which are connected to the generator , so when the fan rotates a very fast current will be induced to these coils and supply an electrical power to the whole aircraft , unless the generator fails then the pilot can switch to battery supply and the pilot can use it temporarily. Not only the electrical power is important in an aircraft but also pneumatic power which we can also get it from the gas turbine engine. When the fan rotates it sucks air. In order for the aircraft to fly without producing too much noise from the engine, the engine takes only from 20 – 25 % of the total air and allows it to go to the core of the engine to be burned with fuel. The other 70 – 75 % of the air by –passes the engine, this air is like extra for the engine and it doesn’t want it, so the pneumatic air takes it and starts to supply it into the cabin, emergency masks , control systems etc. So without these 2 supplies it’s going to be very hard for the cabin crew, passengers and the pilot to withstand this problem.
Bibliography |
3. James , Harry. “Turbine Engines.” Www.free-online-private-pilot-ground-school.com . 26 Nov. 2006. Web. 10 Jan. 2012
