Jet engine

20140308-Jet engine airflow during take-off

Whittle Jet Engine W2-700

Ohain USAF He 178 page61

Junkers Jumo 004

Gloster Meteor III ExCC

JT9D on 747

Jet engine is a type of reaction engine discharging a fast-moving jet that generates thrust by jet propulsion. This broad definition includes airbreathing jet engines (turbojets, turbofans, ramjets, and pulse jets). In general, jet engines are combustion engines.

History

The concept of the jet engine was first proposed by Sir Isaac Newton in his Third Law of Motion. However, it was not until the early 20th century that engineers were able to develop the technology to create a working jet engine. The first successful jet engine was built by Frank Whittle, an English aviator, in the 1930s. Around the same time, German engineer Hans von Ohain was also developing a similar engine. Both Whittle and von Ohain are credited with the invention of the jet engine.

Types of Jet Engines

Jet engines are classified into different types based on their design and operation. The main types include:

• Turbojets: The simplest form of jet engine, where air is drawn in at the front, compressed, mixed with fuel, ignited, and then expelled at high speed out the back.
• Turbofans: Similar to turbojets but include a fan at the front that forces air around the outside of the engine, increasing efficiency. This is the most common type of engine used in commercial aircraft.
• Turboprops: These engines use a jet engine to drive a propeller, offering better efficiency at lower speeds compared to turbojets and turbofans.
• Ramjets: A form of airbreathing jet engine that uses the engine's forward motion to compress incoming air without a rotary compressor. Ramjets work most efficiently at supersonic speeds.
• Scramjets: An evolution of the ramjet, scramjets are capable of operating at hypersonic speeds, where the speed of the airflow through the engine is greater than the speed of sound.

Principle of Operation

The basic principle behind a jet engine is Newton's third law of motion: for every action, there is an equal and opposite reaction. A jet engine takes in air at the front, compresses it, mixes it with fuel and ignites the mixture, then expels it at high speed out the back. This action propels the engine, and thus the aircraft, forward.

Components

The main components of a jet engine include:

• Air Intake: Captures air from the atmosphere.
• Compressor: Increases the pressure of the air.
• Combustor: Where fuel is added and ignited.
• Turbine: Extracts energy from the high-pressure gases exiting the combustor.
• Nozzle: Accelerates the exhaust flow, increasing the velocity of the jet from the engine.

Applications

Jet engines are used in a variety of applications, from commercial and military aircraft to missiles and even some types of boats. They are favored for their high speed and efficiency at high altitudes.

Advancements and Future Trends

The development of jet engines continues to focus on increasing efficiency, reducing noise, and minimizing environmental impact. Advances in materials science and engineering have led to engines that are lighter, more powerful, and more fuel-efficient. Future trends include the development of electric and hybrid propulsion systems that aim to further reduce the carbon footprint of air travel.