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Что такое двигатель apu

Дополнительный двигатель в грузовом автомобиле

Каждый дальнобойщик нередко сталкивался в пути с ситуацией, когда по различным причинам машина вынуждена простаивать несколько часов, а иногда и дней.

Это может произойти из-за распутицы или сильных морозов, проблем с оформлением документов на таможне или у владельца груза. Так что километровые очереди из фур на трассе совсем не редкость.

Зимой такая ситуация становится драматичной. Чтобы не замерзнуть в «железной коробке», водитель вынужден время от времени включать двигатель. Иногда это приводит к тому, что горючее заканчивается раньше времени. В малонаселенной Сибири или северных районах страны это может окончиться большими неприятностями.

Зарубежные производители грузовых автомобилей предлагают оригинальное решение проблемы. В машину устанавливают маломощный дополнительный двигатель с небольшим расходом топлива. Его называют APU (auxiliary power unit), то есть, вспомогательный силовой агрегат. Иногда говорят «вспомогательный генератор».

Что такое двигатель apu

APU (Автономная система подогрева с приводом от дизельного двигателя) позволяет останавливать основной двигатель локомотива в любом месте и при любой погоде.

APU — отдельная система, в основе которой небольшой дизельный генератор, с системами обогрева и автоматики. Система питания APU от дизельного топлива локомотива. АPU поддерживает температуру основных систем главного двигателя, в рабочем диапазоне, готовым к запуску и полным нагрузкам в любой момент времени. Потребляет менее 2х л/час, вместо 30-50 л/час, которые потребляет основной двигатель тепловоза на холостом ходу. Экономит топливо и масло. Уменьшает вредные выбросы в несколько раз.

Железнодорожный транспорт является крупнейшим потребителем энергоресурсов. Затраты на топливно-энергетические ресурсы (ТЭР) составляют в целом по сети железных дорог России примерно 11,2 % от общеотраслевых эксплуатационных расходов, из них на тягу поездов расходуется 72,2 %. Но действительно ли эти 72,2% расходуется на тягу, на полезную работу? Результаты исследований показали, что время работы ДГУ тепловозов на холостом ходу с учетом стоянок в пути следования колеблется в пределах от 40 до 78 %. В режиме номинальной мощности тепловозы работают от 0,5 до 15 % суммарного времени. Остальное время приходится на частичные нагрузки. Следовательно, тепловозы работают основное время на холостом ходу и частичных нагрузках.

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Данное соглашение об обработке персональных данных разработано в соответствии с законодательством Российской Федерации и должно использоваться на всех сайтах где указывается контактная информация.

Все лица, заполнившие сведения, составляющие персональные данные на данном сайте, а также разместившие иную информацию обозначенными действиями подтверждают свое согласие на обработку персональных данных.

Под персональными данными Гражданина понимается нижеуказанная информация: общая информация (Ф.И.О.), номер телефона, адрес электронной почты, адрес доставки.

Гражданин, принимая настоящее Соглашение, выражают свою заинтересованность и полное согласие, что обработка их персональных данных может включать в себя следующие действия: сбор, систематизацию, накопление, хранение, уточнение (обновление, изменение), использование, уничтожение.

Продавец использует информацию для выполнения своих обязательств перед Клиентом.

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Anticipated Impact on Crew

A wide range of practical problems could arise in the cockpit following an engine failure associated with:

  • High workload — Such scenarios are associated with intense workload; the crew will carry out the appropriate engine on fire drills.
  • Engine shutdown — Normally the fire drills require shutting down the engine and cutting off fuel and electrical supply to the engine. Following this, extinguishant is fired into the engine and a visual inspection of the affected engine is carried out by a member of the cabin or flight crew (if possible). It should be noted that an engine on fire could still produce thrust; it is a critical element to consider when dealing with engine fire emergencies on single engine aircraft. In addition, it should be noted also that historically there have been cases of improper identification of the problematic engine followed by wrong engine shutdown.
  • Announcing the problem — the crew will communicate the problem to ATC. Non-standard phraseology should be avoided; an emergency (MAYDAY) or urgency (PAN PAN) call should be made.
  • Seeking information and deciding on course of action — the crew will need any information available regarding adjacent aerodromes and weather conditions if they decide to proceed to and land at the nearest suitable aerodrome.

Spacecraft [ edit ]

The Space Shuttle APUs provided hydraulic pressure. The Space Shuttle had three redundant APUs, powered by hydrazine fuel. They were only powered up for ascent, re-entry, and landing. During ascent, the APUs provided hydraulic power for gimballing of the Shuttle’s three engines and control of their large valves, and for movement of the control surfaces. During landing, they moved the control surfaces, lowered the wheels, and powered the brakes and nose-wheel steering. Landing could be accomplished with only one APU working. [18] In the early years of the Shuttle there were problems with APU reliability, with malfunctions on three of the first nine Shuttle missions. [Note 2]

Your Airliner Has A Hidden Engine!

How many turbine engines are on an Airbus A320?
Two, right? Would you believe three?

How about a Boeing 747?
Four engines? Wrong again. A 747 has Five turbine engines!

Hiding inside the tail of most every airliner is an extra engine called an Auxiliary Power Unit or APU. Time to find out what’s hidden in the tail of your aircraft!

The Honeywell 331 Series APU.
Source: Honeywell

Airliners are loaded with redundant systems to help make them reliable. Years ago, aircraft manufacturers and operators figured out that installing a small turbine engine in an aircraft’s tail is a great way to provide an extra level of safety, convenience, and comfort.

The auxiliary power unit is an actual turbine engine, more appropriately called a turboshaft engine. Unlike the aircraft’s main engines, the APU outputs almost no thrust. Most of the power produced is used to run an electric generator and provide pneumatic (air) pressure.

Comfort and Convenience

The auxiliary power unit is usually run on the ground during passenger boarding and deplaning. The APU turns an electric generator that powers the electrical system on the aircraft when the main engines are off. It also provides pneumatic pressure for air conditioning and, more importantly, starting the main engines. This eliminates the need for using an external power source and a noisy air compressor cart to keep the cabin comfy while boarding.

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Next time you hop on an airliner (even a small regional jet), listen carefully as you board. You’ll hear the familiar whine of a turbine engine, even though the main engines aren’t running. You’re hearing the APU doing its thing!

Safety

The most important job for the APU is to provide redundancy. The APU’s electric generator can be used during flight in case one or more of the aircraft’s main generators have a problem. Similarly, in the event of a pneumatic malfunction in the main engines, the APU can provide compressed air for cabin pressurization and airframe ice protection. The redundancy provided by the APU is one of the reasons twin engine jets are allowed to fly long distances over the ocean. It’s a pretty big job for a small turbine engine hiding in the tail.

Small turbine engine?

Auxiliary power units aren’t exactly small. Many APUs are variants of full size turbine engines used in other aircraft. Check out the classic Garrett (now Honeywell) TPE331 engine: For years it has powered large turboprops like the Jetstream 41, Metroliner, and Beechcraft King Air. A variant of this engine, the Honeywell 331, is used as an APU in many Boeing and Airbus wide body jets. Instead of a propeller, the APU has an accessory shaft that powers a generator.

The Boeing 747-400 APU is a variant of a Pratt & Whitney turbofan engine used on Cessna Citation and Mitsubishi Diamond business jets. This is a very powerful engine. It takes a lot of horsepower to run the systems on the 747 when the main engines are shut down.

Firing up the little turbine engine

Operating the auxiliary power unit couldn’t be easier. The APU control panel on most airliners consists of a switch or button and a couple of lights – that’s it! Starting the unit is as easy as starting a car. APU manufacturers have done a great job designing these engines so they take care of themselves. If there is a problem, the system is smart enough to shut the APU down and let us know. It’s pilot-proof!

Crews normally run the APU before flight for electrical power, air conditioning and engine start. After landing, the APU is started so engines can be shut down as soon as the aircraft arrives at the gate. If the APU is needed during flight, it can be started in about a minute. It’s a wonderful thing!

Watch an APU Start!

The video shows the start sequence of a Boeing 767’s APU (a Honeywell GTCP 331-200). When the flight crew begins the start, the air intake door opens on the aircraft’s tail and an electric motor begins to spin the engine. Fuel is added and within seconds, the APU is up-to-speed and providing electric and pneumatic pressure for various aircraft systems.

Do all airliners have an APU?

Most every modern turbojet powered airliner (including the smaller regional jets) have an APU installed in the tail. Only a few large turboprop aircraft have them due to the weight restrictions of smaller aircraft.

Look for the tailpipe!

Next time you’re at the airport, take a look at aircraft tails. You’ll notice an exhaust outlet for the aircraft’s auxiliary power unit. The APU is hiding inside the tail, just in front of the exhaust. So that’s what the little tail pipe is for!

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Some APU exhausts are on the side of the fuselage, near the tail. Photo Credit: Eric Salard – CC BY-SA 2.0

Where does the APU get its air?

Turbine engines need a lot of fresh air to run. So, where does the APU get its air? You have to look carefully to spot the air intake. The intakes are usually covered with motorized doors that open when the APU is started. The best time to look is when the airplane is at that gate. Once the aircraft is taxiing, the APU will likely be shut down and the door will be closed, hiding its location.

APU Trivia!

  • The first airliner to have a gas turbine APU was the Boeing 727 in 1963. The 727 was designed for smaller airports with little (or no) ground support equipment. The 727’s APU was located in the main landing gear bay. The exhaust was through louvers in the top of the right wing!
  • Aérospatiale-BAC Concorde didn’t have an APU. Because the aircraft was small and extremely weight sensitive, it was designed without an APU. Concorde only operated into large airports with plenty of ground support equipment.
  • Two other classic airliners, the Boeing 707 and Douglas DC-8, were also built without an APU. These airplanes were widely used well into the 1990’s and beyond. A few of these aircraft were modified to include an APU in a wheel well. The KC-135 tanker (a variant of the 707) was upgraded to include an APU in its tail.

APU – The little turbine engine

All large commercial aircraft have an auxiliary power unit onboard, usually located in the tail of the aircraft (although some regional jets vents to the side). This is a small turbine engine, essentially the same design and operation as the main aircraft engines but on a smaller scale. However, unlike the main engines, the APU does not provide thrust (hence it would be wrong to call it a jet engine). Instead, it powers an electric generator and provides air pressure.

A Honeywell APU (it produces APUs for all Boeing 737 and Airbus A320 aircraft). Photo: YSSYguy via Wikimedia

Why have this extra engine when you already have two or four much larger ones? The APU has several functions related to safety, convenience, and economy.

The “rat”

Should even the APU have a bad day, the on-board battery could supply the cockpit with power for at least 30 minutes. In this case, a small propeller will also pop out of the fuselage. This so-called ram air turbine, in short RAT, and affectionately called “rat” by pilots, functions as last instance. But more on this essential “creature” soon in another article.

The APU is thus a complex and incredibly important element of the system “aircraft”. Even after landing, the APU is switched on again immediately so that it is not “in the dark” after shutting down the engines.

If you soon have the opportunity to walk from the bus to the plane again, you can almost always hear the small turbine hissing loudly in the background.

Here “Captain” Joe explains to you once again on his YouTube channel what an APU is:

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