That future of flight includes travel to space, as envisioned by the likes of XCOR, which, as shown in the above video, hopes small rocket-powered craft can unlock Earth's orbit to civilian explorers. But as GE's John Deaton tells us, jet engines will power the world's travel for many years to come, and as he told us, highly-detailed, 3D-printed parts will make up the more efficient, more reliable jet engine of tomorrow.
The first turbojet engine was patented in 1930 by the British engineer Frank Whittle, and in the decades since (along with the advent of the turbofan), jet engines have been put to use in a variety of applications, from passenger liners to helicopters.
Regardless of the application, the basics of how they operate remains the same. Through a front intake, air is sucked in, compressed, and sent to combustion chambers. There, flames of burning jet fuel, heating up the oxygen, which expands and shoots out the back, generating a massive amount of thrust needed to lift modern aircraft into the sky (or spin a turbine . On the way out of the exhaust, the burning fuel and air also passes through a turbine, which in turn helps power the compressor.
These days turbofans are the most widely used in military and civilian aircraft. Turbofans operate just like every other just engine, with a slight twist. Some of the air that’s brought into an engine front is bypassed by a turbine in the front of an engine, in order to use some of that air to cool the engine and as thrust.
There are two types of turbofans—one that’s better suited to civilian use, and another that militaries across the globe have adopted (and are also better for smaller jets). The civilian version is known as a high-bypass turbofan, because the engines are designed to allow more air to bypass the combustion stage.
There are a couple reasons for doing so. First, with more air going around the turbines the engines are cooler, and less noisy—and noise is important for commercial flights. Since less air is roasted in the combustion chamber, high-bypass turbofans also use less fuel.
Low-bypass turbofans are popular with the military because they’re more effective at providing sufficient thrust in the low supersonic range—Mach numbers one through three—than their counterpart. As a result, many engines designed for those speeds aren’t great at operating under certain conditions, such as taking off from high altitude airports, and accelerating through transsonic speed. To compensate, militaries often add afterburners to planes with low-bypass turbofans to increase thrust in certain situations.
An afterburner is basically a second combustion chamber located right in front to the engine’s exhaust nozzle. The plane’s fuel injection system squirts gas into it, a lighter sets it on fire, and exhaust roars out of the nozzle at about 1750 ºC. Afterburners burn tons of gas—hence they’re used on military aircraft almost exclusively. Still that face melting heat can boost a turbofans’ output by up to 50 percent.