How Does A Jet Engine Work?

A jet engine is a famous type of engine. Jet engine forces the aircraft forward with immense power, allowing the aircraft to go too high. The same idea applies to all aircraft engines, commonly these engines known as gas turbines engine. The engine pulls the air with a fan. The compressor increases air pressure. 

The Second World War started in the era of jet engines. Jet engines operate in a completely different way than previous engines. Imagine sitting on a wheeled table with a bowl of baseball. The frame rolls you in another direction as you chuck a baseball. You won’t get into the path if you chuck a baseball at a moment.

jet engine

According to Newton’s third law, every action has an equal but opposite reaction. When you throw the ball, the same magnitude force acts backward and is barely noticeable on the ground, While standing on the ice or kayaking, you might be in for a surprise if you’re not ready.

The jet engine works on the same principle: when air sucks back, it has the power to react forward.

                                           Force = acceleration x mass

Air is not very heavy. So if you are using a lot of force to move a large object like an airplane, you will need a lot of air to do a small acceleration at a reasonable speed, a very large acceleration for a smaller amount of air, or something in the middle.

Combustion of gasoline and exhaust happens in the same direction and pushes the engine opposite. Jet engines still work under this concept but have a supply of oxygen that burns fuel in a vacuum.

History of Jet Engine

The concept of a jet engine was first proposed to UK student Frank Whittle in 1928. In 1937, he proved this in the laboratory, and in 1941, the British RAF started using the first aircraft, the Gloucester E.28. Meanwhile, three German engineers developed the same idea from early to the mid-1930.

Hans von Ohine conquered England in 1939 and produced the world’s first plane with the HE-179 experiment. The Bell P-59A Aira Comet designed in 1941 was the first American airplane. Other planes, like the famous Messer Schmidt Me262, continued until the end of the war.

Mainly used as fighter jets, these aircraft were quicker and cheaper than current aircraft but reduced in reach and less maneuverability than the perfect one. In comparison, it was not manufactured in amounts that would have a major effect on the battle. But after the war, military and commercial aviation grew dramatically.

Working Principle of Jet Engines

The jet engine propels the aircraft with immense power, which lets the aircraft move rapidly.

The jet engines, sometimes referred to as gas turbines, run under the same concept. The motor pulls air from the front through a fan. Air friction rises by the engine. The compressor is made up of many blades on the shaft.

Turbojet engine working

The blades spin at fast rates while the air is compressed or squeezed. The petrol is first sprayed into compressed air and the mixture is sparked by an electrical flame. The flue gas spreads and is separated from the engine via the dust. The turbine and aircraft are forced back as the gas injector explodes. The hot air moves through another set of blades named a turbine on the way to the jar. The turbine is attached to the same compressor shaft. Turbine movement induces the rotation of the compressor. For jets that are slower than tone, the jet flies about 1000 km/h through the air (600 mph). At this speed, you can picture the engine heading toward it at rest and cold air.

How Does A Jet Engine Work?

Thrust is the main result of a jet engine. To get thrust you need to blow air out of the nozzle (basically the converging part). For the air to exit the nozzle automatically, the high pressure at the nozzle inlet must be maintained in two steps. In the very first stage, a compressor compresses the incoming air, raising its temperature and pressure. But it’s not too high as it takes to create great thrust. To this end, there is a second combustor stage that burns a small amount of fuel to burn the air and increases the temperature and volume of the fuel, both of which participate in the final pressure thereby keeping the air at the nozzle inlet. Now let me take you to step by step through a jet engine.

jet engine working, turbojet engine

The first is the inlet where the atmosphere flows into the engine, slowing down the speed and increasing the pressure. The second stage is a compressor with moving blades that increase the pressure of the air flowing through it. A compressor is crucial for the operation of the combustion chamber. Why? How does the compressor increase the air pressure through the moving blades? That’s another day’s story. Currently, compressed air enters the combustion chamber where it mixes with the fuel and burns at very high temperatures. These high temperatures and pressures are really necessary but must be reduced before they can use on the nozzle.

Also, as I mentioned earlier, the compressor uses moving blades, so you have to invest energy. These two requirements can be met simultaneously in a single device called a turbine. Its purpose is mainly to use high pressure and temperature gas from the combustion chamber to rotate multiple vanes mounted on the same shaft as the compressor. For this reason, the compressor runs as the turbine runs. Finally, after rotating these heavy blades, the air has the ideal parameters and can suck into the nozzle. The air accelerates by the nozzle and pushes the engine in the reverse direction.

Nowadays, some engines have completely removed the compressor and turbine components. Such as scramjet and ramjet engines etc. These types of engines generate tremendous thrust as it is clear that the turbines do not use any of the energy in the air before being submerged in the nozzle. Why don’t you use them often? Because they don’t work independently. so, they can only work at high speeds to make the airplane supersonic.

Parts of Jet Engine

The key components of the jet engine are given below.

jet engine parts

1) Fan

The fan is the first turbofan engine part. A large spinning fan pulls a lot of air. The fan blades are mainly constructed of titanium. And the air is speeded up and halved. A continuous section that travels through the middle or hub of the engine powered by other motor components.

jet engine fan

The second element “lowers” the heart of the engine. The core moves through the surrounding tube goes behind the turbine, where the most force is generated by moving the aircraft forward. This cold air increases engine pressure and decreases noise.

2) Compressor

Main Article: Compressor

jet engine compressor

The compressor is the jet engine core’s first part. The compressor comprises of many fan blades and is mounted on the shaft. This component of the engine moves the input air into ever narrower regions and raises air pressure. This raises the air’s possible capacity. Compressed air is forced into the chamber of combustion.

3) Combustor

Air is combined with the combustible in the burner until it is lit. To spray fuel into the air stream, up to 20 pins are available. The blend of air and gasoline ignites. This guarantees high temperature, high flow of electricity. The gasoline burns oxygen which creates an expanding heat gas in compressed air.

combustion portion

The interior of the combustion chamber is normally constructed of ceramic content to maintain the chamber’s thermal stability. The turbine receives a huge volume of energy from the burner to spin the turbine blades. A shaft that rotates the compressor blades and the pre-sucking ventilator attaches the turbine. The broad energy flow used to power the fan and compressor use relatively little energy. The gas produced in the combustion chamber travels and rotates its blades in the turbine. Thousands of cycles in the jet engine rotates. It is mounted on a shaft between them with multiple ball bearings.

4) Nozzle

It is literally part of the generator of the aircraft that produces an impulse. In addition to the cold air, which passes around the engine core and pushes the aircraft forward. as it leaves the jetty, high-density airflow with the energy flowing through the turbine produces the force which pushes the jet engine. The mixture of warm air and cold air is exhausted and exhaust is emitted and the vehicle is advancing. There will be a mixer in front of the nozzle that mixes warm air coming from the heart of the engine with cool air flowing through the fan. The agitator improves the engine‘s quietness.

 Nozzle
                              Fig: Jet Engine Nozzle

Types of jet engines

The working of the all-gas turbines and jet engines is almost the same (sucking air through the suction valve, compressing the air, burning it with fuel (petrol or diesel), and expanding the exhaust gases through the turbine). Therefore, all five essential parts are shared. A combustion chamber, a compressor, a suction valve, and a turbine arranges, and a drive shaft pass through them.

Various types of jet engines have additional parts (driven by turbines). The intake ports work in several methods. There may be multiple combustion chambers, multiple turbines, and more than one compressor. The applications of each engine are also very significant. Aircraft engine design is a well-thought-out compromise. It should be as quiet, light, and small as possible while achieving maximum performance with the lowest fuel consumption (i.e., maximum efficiency). The gas turbine used on the land (e.g., gas turbines in power plants) does not have to be compromised in the same way. It certainly takes maximum efficiency and performance, but it doesn’t have to be light or small.

There are many types of jet engines, but famous types are given below.

1) Turbojets Engine

Recently this type of jet engine is widely used in aircraft. A turbine engine may define as any device that exploits power from fluids by the controlled mechanical space that utilizes Newton’s law of inertia and acceleration that generates or consumes energy to achieve new desired results.

turbojet

The turbojet engine is the most straightforward jet engines based on gas turbines. This is a primary “rocket” jet that propels an aircraft forward by injecting hot exhaust gases backward. The exhaust from the engine is faster as compared to cold air entering the engine. This is how a turbojet engine generates thrust. In a turbojet engine, the turbine only has to drive the compressor so that the power consumption of the exhaust nozzles is relatively low.

The turbojet engine is a basic, general-purpose engine that produces consistently stable power. Therefore, they are suitable for low-speed and small aircraft that don’t need to do anything mainly good (such as sudden acceleration or a lot of power).

2) Turboshaft Engine

You should not consider that a jet engine powers the helicopter. The helicopter has huge rotors on the top that perform the overall work. One or more gas turbine engines provide power to these rotors that are known as turboshaft engines.

turboshaft, jet engine

The difference between a turbojet engine and a turbo-shaft engine is very large, as the thrust generated by the exhaust gases is relatively small. As a substitute, a turbojet’s turbine consumes maximum power, and the turbine drive shaft turns one or more gears that further turn the rotor and gearbox. In addition to helicopters, ships, tanks, and trains are also equipped with turboshaft motors. Gas turbine engines that are installed in powerplants are also turbine shafts.

3) Turbofan Engine

Main Article: Turbofan Engine

The front of the giant aircraft is equipped with huge fans that act as super-efficient propellers. These fans operate in two approaches. The fans slightly raise the airflow through the engine core, and using the same fuel produces more thrust (which improves efficiency). These fans also blow air around the main engine, completely bypassing the core and creating a propeller-like air backdraft. In simple words, the thrust generated by a turbofan is partly similar to a turbojet engine and partly similar to a turboprop engine. Low bypass turbofans move all of the air through the core, while high bypass turbofans move more air through the core.

turbofan engine

The measurement of the bypass ratio gives you the amount of air (weight) that flows around or through the core of the engine. With high bypass engines, the ratio can be 10:1. This means that the amount of air that passes through the core is ten times greater than the amount of air that passes through the core. Remarkable efficiency and power make turbofan the engine of choice for everything from traveler jets to combat aircraft (low bypass). The bypass design can also cool and silence the jet engine.

The turbojet is less useful than 20%. The design and range of turbofans vary from application to application, but all turbofans have more efficiency as compared to turbojets. A good turbofan can reach 40% in actual operation.

4) Turboprops

Modern propeller-driven aircraft often use turboprop engines. A turboprop engine is very likely to turbo-shaft. Like the helicopters, the internal turbine does not drive the top rotor but turns a front-mounted propeller to propel the aircraft forward.

turboprop engine

Unlike turboshaft engines, turboprop engines generate some forward thrust from the exhaust, but most of the thrust comes from the propellers. Propeller planes fly at low speeds, which reduces the waste of energy to withstand drag, and is very useful for large cargo planes and other light, small airplanes. However, the propeller itself creates a lot of drag, which is one reason why turbofans were industrialized.

How are jet engines so reliable?

Power stations (including powerplants that use local electricity), ships, helicopters, military aircraft, and commercial aircraft are using Jet engines. These applications have diverse regulations. Some of these need more reliability and security to protect the public while others need to protect workers and crew members. All of this requires reliability to be profitable.

In general, two types of reliability are low cycle and high cycle. High cycles cover things that occur more frequently than one operating cycle, such as vibration and component wear. The low cycle is the same as the operating cycle and can be long as it can vary depending on the specific airport environment. Both require a lot of work.

The core of a jet engine consists of many main shafts equipped with turbines, compressors, and fans. Ideally, these components of an engine don’t move back and forth like the pistons in an automobile engine, reducing zero loads and crossover events that cause certain wear and stresses. The first way to improve reliability is to control bearing loading as the engine expands and contracts over the wide temperature range of the engine operating range and flight envelope in the aircraft applications.

The second way to aid reliability is to control the temperature. While it is effective in maximizing fuel economy and operating at higher temperatures during the combustion process, turbine parts have specific heat capacity even as turbine parts are coated and cooled. After the engine is switched off, the engine temperature also changes. There is a large amount of latent heat that must be controlled to ensure reliability for further operating cycles. The auxiliary systems of a jet engine have grown in complexity since the first ones were made.

Compared to large engine turbomachines, these often-present greater challenges in terms of reliability. These errors can be more common but are generally easier to substitute. Some auxiliary parts can be duplicated. So, if one component fails, another similar component can take control. Other parts may have a failsafe mode. The importance of each part of the control system in regulation is broad and generalized.

Various parts of the jet engine have various properties, especially how they wear out. This affects the usage redundancy, protection, and pattern of each type of component throughout the operating cycle. All of this enables the engine to meet maintenance intervals.

The regulations also specify the number of engines on the aircraft and the number of engines required to reach the destination or diversion airport. A twin-jet aircraft can run a full cycle with one engine. A four-jet aircraft can take off with three engines running and land on two of them. Carrying large numbers of passengers on an airplane is very costly, so it makes economic sense for manufacturers to increase the reliability of their engines. In such a competitive business, reliability is the only way to earn a profit.

Why are jet engines so difficult to manufacture?

In engineering, some things are always difficult and expensive. The jet engine is one of them. The thing that makes jet engine manufacturing difficult are given below.

1) High thermal range: jet fuel burns in the engine at a temperature of 2000 ° C, but the aircraft can fly below -50 ° C in the air.

2) High Precision: the tolerance within jet engines (distance between two interacting moving components) is very tight and closer than with normal engines.

3) High speed: jet engine compressor blades rotate at astounding speeds – thousands of rpm.

4) Reliability: Jet engines require high reliability (for example very high), that’s obvious.

Now put all these things together, and the materials and the manufacturing techniques and equipment start to get pretty expensive.

5) Accuracy: Because of the high precision of jet engine components (particularly engine blades), it takes a lot of work to design such balanced parts for the engines that produce such high power for that particular jet engine size. Compared to internal combustion engines (ICE), the end product requires more engineering construction.

For example, when talking about the engines of formula cars, this comparison will be interesting because extreme demands are placed on the combustion process of the internal combustion engine to supply a lot of energy, which is more than commercially manufactured vehicles. Exceeds requirements (like cars).

6) Efficiency: Jet engines are simple in terms of combustion cycles but very complex in terms of improvements in efficiency and reliability. We are confident that the man-hours required from design to manufacture of a jet engine are more than 100 times that of an integrated cycle engine.

During the test, the jet engine must withstand torture. Throw away streams, bones, meat, and other items to avoid spilling the engine.

The production efficiency is not very high, and there are many prices resulting from the price that expensive people can buy.

How does the compressor in a jet engine work?

The compressor is a major component t of the jet engine and only compresses it. It is usually a sequence of various blades from the inlet to the front of the combustion chamber.

compressor working

The functional principle of a jet engine consists of sucking air from the inlet opening and sucking it back again with the blades of the compressor. As the air moves back more, it is compressed under high pressure as it passes through each stage of the compressor. The high-pressure air then enters into the combustion chamber where it mixes with the fuel and ignites. The thermally expanded mixture flows from the combustion chamber through the turbine, which drives the compressor and other components. Eventually, the high-temperature air is expelled from the exhaust gas at high speed as a thrust.

Can We Implement Jet Engine in the Aeroplane?

aircraft

  • There are no theoretical or practical limitations (at the design or engineering level) to the use of jet engines in aircraft.
  • But they are not profitable. Rather, it will place severe restrictions on the kind of people who would be able to afford a ticket.
  • In the concept of future polar supersonic aircraft (Mach 3 and higher) or hypersonic (> Mach 5) airplanes may require Rocket Jets to provide an initial boost to the ramjets or scramjets, which are taken into account in these concept aircraft.

 Differences between a Jet Engine and an Internal Combustion Engine

jet engine vs ic engine

  • The jet engine is an open system. Alternatively, it can be called a volume control system. On the other hand, internal combustion engines are an example of a closed system or a mass control system.
  • Another difference is that the jet engine regularly creates work. The IC motor, on the other hand, only generates work during a specific stroke.
  • The blades of the jet engines are in constant contact with the hot gas during the entire operation. In contrast, the internal combustion engine cylinders and pistons are exposed to high temperature and pressure for a very limited time during the cycle. Therefore, the maximum temperature of the internal combustion engine is higher than the maximum temperature of the jet engine.

See More:

1) What is an engine and its different types.

2) Turbine and its different types

3) Gas Turbine

 

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