How Does A Jet Engine Work? | What are types of Jet Engines?

This article explains the jet engine working, types, parts, and applications.

What is a Jet Engine?

A jet engine is a type of propulsion system that utilizes the principle of jet propulsion to generate thrust. It works by expelling a high-velocity stream of heated gas, usually air, which produces forward motion in the opposite direction.

The 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 are 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.

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 push the aircraft forward.

                                           Force = acceleration x mass

The 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.

The 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 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.

Working of Jet Engine

Thrust generation is the main purpose 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.

After the first stage, the second stage starts. In this stage, the air-fuel mixture burns in the combustion chamber and generates heat. Now let me take you step by step through a jet 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. The 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.

As we mentioned earlier, the compressor uses moving blades, so you have to invest energy to run it.  The high pressure and temperature gases from the combustion chamber are used to rotate turbine blades mounted on the same shaft as the compressor. For this reason, the compressor runs as the turbine runs.

After rotating the turbine, 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. 

Parts of Jet Engine

The key components of the jet engine are given below:

1. Inlet
2. Shaft
3. Gearbox
4. Compressor
5. Turbine
6. Fuel system
7. Nozzle
8. Lubrication system
9. Combustion chamber

1) Inlet (Intake)

The inlet of the engine is used to introduce fresh air into the engine.

2) Turbine

The turbine is one of the major parts of the jet engine. It is used to remove energy from the exhaust gases that is used to drive the compressor and other engine parts. Turbines may be single-stage or multi-stage.

3) 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.

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

4) Fuel System

The fuel system contains a fuel pump, fuel lines, and valves. It is used to supply fuel to the combustion chamber.

5) Compressor

The compressor is the jet engine core’s first part. The compressor comprises 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.

Read More: Different Types of Compressors

6) Combustion Chamber

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 and a high flow of electricity. The gasoline burns oxygen which creates an expanding heat gas in compressed air.

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 to the turbine. The broad energy flow used to power the fan and compressor use relatively little energy.

The heat produced in the combustion chamber travels and drives the compressor. 

Read More: Combustion Chamber Working and Construction

7) 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.

8) Lubrication System

It has the responsibility to properly distribute the engine oil to different engine parts to reduce friction and wear.

9) Engine Control System

The engine control system is a combination of hydraulic, mechanical, and electronic parts that manage and control different functions of the engine.

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.

The jet engine has the following types:

1. Turbojet 
2. Turboshaft 
3. Turbofan
4. Turboprop 

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.

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 which are known as turboshaft engines.

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 power plants are also turbine shafts.

3) 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.

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.

Read More: Turbofan Engine Working and Types

4) Turboprop Engine

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.

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.

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.

• 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.
• High Precision: the tolerance within jet engines (distance between two interacting moving components) is very tight and closer than with normal engines.
• High speed: The compressor blades rotate at astounding speeds – thousands of rpm.
• Reliability: Jet engines require high reliability (for example very high), that’s obvious. Now put all these things together, and the materials and manufacturing techniques, and equipment start to get pretty expensive.
• 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.
• Efficiency: Jet engines are simple in terms of combustion cycles but very complex in terms of improvements in efficiency and reliability. The production efficiency is not very high, and there are many prices resulting from the price that expensive people can buy.

Differences between a Jet Engine and an Internal Combustion 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.

Applications of Jet Engines

• Jet engines are most commonly used to power the commercial aircraft.
• Jet engines such as turbofan or turboprop engines are used in business jets and some smaller general aviation aircraft.
• They are employed in military aircraft because of their high power-to-weight ratios and the capability to run at high speeds and altitudes.
• Turboshaft engines are used to power the helicopters.
• They are utilized to power different aerospace applications, including rocket boosters and powering launch vehicles.

• These engines are sometimes employed in some high-speed marine applications like experimental naval vessels and hydrofoil boats.

FAQ Section

Why it is called jet engine?

A jet engine produces thrust by expelling a high-velocity jet of exhaust gases. The term “jet engine” is derived from the fact that it depends on the principle of jet propulsion, where a quick expulsion of exhaust gases from the engine generates an equal and opposite force in the forward direction, propelling the aircraft forward.

What are the ypes of Jet Engines?

1. Turbojet 
2. Turboshaft 
3. Turbofan
4. Turboprop

What are the parts of Jet Engines?

• Intake
• Compressor
• Fan
• Combustion chamber
• Turbine
• Nozzle
• Turbine
• Fuel system
• Lubrication system
• Engine control system

Can We Implement Jet Engine in the Aeroplane?

• 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.

Why are jet engines so powerful?

Jet engines are so powerful because of their unique method of generating thrust. These engines create thrust by raising the internal pressure through a combustion process. This heightened pressure results in a stronger force being exerted in the forward direction, enabling the jet engine to reach higher speeds.

Which fuel is used in Aeroplane?

Aviation kerosene, commonly referred to as QAV, serves as the fuel for aircraft and helicopters fitted with turbofans, turboprops, or jet turbines. Its primary application can be found in commercial air transportation.

What are the jet engines used for?

Jet engines are usually used for different aircraft, including private, military, and commercial aviation.

Read More

1. Different types of Engines
2. Different types of Turbines
3. Working and types of Gas Turbines