Turbofans are used in most aircraft jet engines and some vehicles for increased fuel efficiency and reduced noise. They have a front-mounted turbine that channels air in two directions, with a small portion burned for thrust and the rest mixed with exhaust gases for increased thrust and cooling. Advanced designs use gearbox control systems to increase efficiency and reduce emissions. Military aircraft use hybrid versions with afterburners and thrust vectoring for high-speed maneuvers.
A turbofan is a type of air compression system used in most aircraft jet engines as of 2011, as well as some high-performance cars, boats, or specialized air-powered vehicles such as hovercraft or helicopters with turbofan. It is considered an improvement over turbojet or turboprop engines at normal commercial aircraft speeds due to increased fuel efficiency and reduced noise, and the turbofan gas turbine engine is also incorporated in many subsonic military aircraft. The first air turbofan jet engine was produced in 1943, but problems with the efficiency and reliability of early designs compared to that of turbojets delayed their widespread adoption until the 1960s.
A basic design for a turbofan engine has a front-mounted turbine that draws in air and channels it in two directions. A small portion of the air is channeled into a central combustion chamber, where it is heated by burning fuel and is ejected from a jet nozzle at the rear for thrust. The remaining air is channeled around the combustion chamber to mix with the exhaust gases from the combustion process, as it is channeled out of the chamber by an exhaust turbine. This increases the engine’s thrust capacity, reduces noise levels and cools the combustion chamber simultaneously. Such engines are known as bypass turbofans, where the ratio of bypass air channeled around the engine to air used for combustion is in the range of 8 to 1, or more.
The invention of the turbofan engine was a significant improvement over piston engines, as the direction of motion in the engine was in a rotary direction, reducing overall aircraft vibration. While the parts of a simple turbofan engine rotate at the same speed, more advanced engines from 2008 have a gearbox control system to increase their fuel efficiency level by 12% or more, as well as Reduce noise and waste gas emissions by up to 50%. These gearbox turbofans try to match the speed of the bypass air to the speed of the plane itself, where earlier designs used the higher speed of the bypass air to drive the exhaust turbine for extra thrust. By controlling each part of the compression and exhaust process individually, the engine’s efficiency level can be adjusted to the aircraft’s speed and attitude, increasing overall efficiency.
Military aircraft that can fly above supersonic speeds of MACH 1.6 or higher and need high performance features use hybrid versions of the turbofan. At supersonic speeds, jet engines with simpler designs, such as turbojet or ramjet engines, have a much higher thrust-to-weight ratio than the turbofan, but perform poorly at subsonic speeds. These aircraft engines have additional features therefore such as afterburners and thrust vectoring. Afterburners inject additional fuel behind the engine’s turbines and ignite it, giving the plane a powerful boost for high-speed aerial maneuvers. Thrust vectoring is also used to control aircraft attitude by adding movable jet exhaust nozzles on the turbofan engine, where the exhaust exit angle can be changed. This can help in sharp turns in the air, vertical take off like with the Harrier jet, or create reverse thrust to quickly stop an aircraft on a short runway.
Protect your devices with Threat Protection by NordVPN
