Afterburners are designed to increase the fuel burn but this inefficient process results in a higher amount of waste energy. Noise is another drawback of this design. It occurs later and is harder to control. In this article, we will discuss the noise caused by afterburners and how it impacts aircraft speed.
Problems with afterburner design
Afterburner design is a complex problem because it must be able to operate without affecting the normal operation of the main turbojet engine. An afterburner is a full-scale engine attached to the exhaust of a turbojet engine to increase the temperature of the jet gases after leaving the turbine. Early designs were evaluated for their advantages and disadvantages, and suggestions were made for future development.
The design of an afterburner is often optimized to provide a large boost in thrust during takeoff and transonic acceleration, as well as during combat maneuvers. However, this feature is extremely fuel-intensive and is only suitable for a short portion of a mission. Further, the fuel requirements of afterburners limit their use.
Fuel efficiency
Fuel efficiency afterburners are a common feature of modern aircraft. This feature helps aircraft achieve supersonic speeds, but it also causes a loud exhaust plume. Afterburners are generally used in military aircraft. They are standard equipment for fighter jets. They have also been used in NASA research aircraft and on Concorde, the first commercial aircraft to achieve supersonic flight. Afterburners reduce the amount of time an aircraft spends in the high drag transonic flight regime, which is also known as supercruise.
The loud noise is caused by the afterburner increasing the fuel burn and producing more waste energy. The volume of this waste energy depends on the shape and the level of turbulence. It is possible to reduce the volume of the exhaust by modifying the shape of the nozzle. But the noise is still noticeable.
Noise level
During takeoff, a B-1B bomber produces an intense amount of noise. The noise is so intense that it causes “all circuits to be busy now” messages to pop up on airport phone lines. It didn’t set a record, but it was still loud enough to disturb people living near the LB Airport. The sound was measured at Monitor #9 near Carson St. west of Cherry Ave., and it reached 114.9 dB for 79 seconds.
Noise levels are produced when exhaust gas exits the afterburner. This is due to two main processes: mixing and shock waves. The first occurs when exhaust gas combines with ambient air and the second occurs when the jet reaches supersonic speeds. This process creates both a mixing noise and shock noise, which are the two main components of jet noise.
Noise levels of aircraft engines vary greatly. The F-15C produced a decibel level around sixty-six decibels, while the F-22 produced a decibel level of 141-142 decibels at a distance of 40 feet. By comparison, a conversational speaker’s decibel level is around 60 decibels. This difference is very small if the afterburner is used for the same amount of time and at the same location.
Impact on aircraft speed
Afterburners are used to boost the speed of aircraft by allowing them to produce more thrust from the same turbomachinery. This type of engine uses a separate combustor downstream of the jet pipe, resulting in a significantly higher exhaust temperature and jet velocity. This type of engine has a limited life, due to the fact that it can only be used intermittently.
Afterburners use a series of small tubes that spray fuel from hundreds of small holes in the engine. A device called an electric spark ignites the fuel, which is then released. Afterburners are most often used for carrier takeoffs. The extra speed from an afterburner is useful in combat situations.
A pilot must allow the aircraft three minutes of flight without afterburning. This is to avoid damaging the plane’s tail. However, combat pilots may not be aware of this limit and may choose to go beyond it in an emergency. If this happens, they may be removed from operations and must undergo depot-level maintenance, which could be costly for a carrier-based squadron.
