A gas turbine is a device with a series of angled blades attached to a central hub. When air flows past those blades, they spin at very high speeds. In the case of a jet-engine-powered car, the turbine powers an electrical generator first—and then an electric motor that drives the wheels.
A turbine is a device with a series of angled blades attached to a central hub, like the fan on a boat motor. When wind or water flows past the blades, they turn, which turns the hub and powers whatever is attached to it. A turbine can be used in lots of different ways:
- Motor: Water flowing through a pipe can power turbines that spin generators to make electricity.
- Propeller: Wind turbines have propellers that are powered by wind instead of an engine. The spinning motion of the propeller creates energy that can be used for electricity or stored until it’s needed.
- Generator: A turbine spinning inside generators creates electricity through electromagnetism.
- Engine: Turbines are also engines! Francis taught us how turbines can power engines, including jet engines.
In the jet engine, these blades are mounted on a long shaft and spun at high speed. The spinning shaft is housed in an airtight case that has an air intake at one end and a nozzle to exhaust hot gases at the other.
In the gas turbine engine, these blades are mounted on a long shaft and spun at high speed. The spinning shaft is housed in an airtight case that has an air intake at one end and a nozzle to exhaust hot gases at the other.
The air that enters through the intake goes through a compressor (a series of turbine blades, similar to those on the shaft) that squeezes it together into high-pressure air.
When you observe the jet engine, it is easy to see that air enters through the intake. What happens to this air once it enters?
Once inside, the air goes through a compressor (a series of turbine blades, similar to those on the shaft) that squeezes it together into high-pressure air. The squeezed air continues and reaches a section where fuel is injected and ignited with spark plugs. The hot gases produced by this combustion process expand rapidly in the combustion chamber and rush out through nozzles at an increased velocity. This causes the thrust to be created by Newton’s 3rd law of motion: for every action, there is an equal and opposite reaction.
From there, it goes into a combustion chamber where fuel is squirted in and burned by tiny jets of burning gasoline that poke into it from all directions, creating more heat and pressure — about 1,000 degrees Fahrenheit (538 degrees Celsius) and 1,200 pounds per square inch (83 bar).
The hot, high-pressure gases coming from the combustion chamber are directed through a turbine, which powers all of the moving parts in an engine (like its compressor). The gas then exits at supersonic speeds through a nozzle. This creates thrust for an airplane: As it pushes out of the back of the engine, it pulls the plane forward in much the same way that water pushing out of a fire hose makes it move.
Although we can thank a man by the name of Vannevar Bush for this device, Britain had earmarked the invention during the Second World War in an effort to hasten its end. In 1939, RJ Mitchell of Supermarine began work on a project code-named Type 3001 to create the first military aircraft design with a pure-jet engine. Due to the weight and SFC of piston engines at that point in time, the project was torpedoed due to its inefficient design. Aside from Germany which had saucer-style designs in place, it wasn’t until 1942 when Germany’s Dr. Hans von Ohain began work on an axial-flow turbojet design equipped with an afterburner where it would serve as an alternate powerplant for Luftwaffe aircraft.
However, it wasn’t until late 1944 that turbojet-powered aircraft finally began appearing on the battlefield with the Me 262 and Gloster Meteor. This type of engine is extremely common. Almost any airplane that you go on uses it in some capacity, whether it be to move the aircraft forward or to increase its speed. They have been refined over several decades and will continue to be refined until the end of time. It is important that the jet engine continues to develop, as well as that we continue to make new innovations with this type of engine so that planes will continue to travel at top speeds safely.