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Секция «Актуальные на учные проблемы в мире (глазами молодьш исследователей)»
УДК 629.7.03=111
ТИПЫ АВИАЦИОННЫХ ДВИГАТЕЛЕЙ, У КОТОРЫХ ЕСТЬ БУДУЩЕЕ
А. М. Турчанов Научный руководитель - П. Р. Чирков Руководитель по иностранному языку - А. Н. Ефимова
Сибирский государственный аэрокосмический университет имени академика М. Ф. Решетнева
Российская Федерация, 660037, г. Красноярск, просп. им. газ. «Красноярский рабочий», 31
Е-mail: flighttt1994@yandex.ru
Эффективность является самым важным параметром для любого двигателя. Для авиационных двигателей это решающий фактор, который определяет, возможно ли использовать данный двигатель в авиации. Различные типы двигателей, устанавливаемых на самолётах, могут иметь большую или меньшую стоимость производства, быть легче или тяжелее по весу, более или менее мощными. Существует также проблема снабжения топливом и его стоимости. Тем не менее, в качестве силовых установок на воздушных судах используются разные типы двигателей, каждый имеет свои особые преимущества, и все они будут ещё долгое время находить применение в авиации.
Ключевые слова: эффективность, поршневой двигатель, газовая турбина, вес, стоимость.
TYPES OF AVIATION ENGINES THAT HAVE A FUTURE
А. M. Turchanov Scientific Supervisor - P. R. Chirkov Foreign Language Supervisor - A. N. Efimova
Reshetnev Siberian State Aerospace University 31, Krasnoyarsky Rabochy Av., Krasnoyarsk, 660037, Russian Federation Е-mail: flighttt1994@yandex.ru
General efficiency is the most essential parameter of any engine. For aviation engines, this becomes the decisive factor, which determines whether the engine can be used in aviation or not. Different types of engines applicable for aircraft may be more or less money-consuming in manufacture, heavier or lighter, more or less powerful. There is also a problem offuel supply and cost. But still, different types of engines are used as aircraft powerplants, each of them has its specific advantages, and they all are supposed to be aviation engines for a considerable period of time to come.
Keywords: efficiency, piston engine, gas turbine, weight, cost.
Aviation engines are the most essential, the most expensive, and also one of the most complex components, the production of which is aggravated by lots of technological problems. The most important parameter of an engine is its power density (specific impulse), i. e. the number of kilowatts or horsepower per unit of mass. This parameter constitutes general efficiency of an engine: if there is a heavy engine installed in a car or lorry, the vehicle will still be capable of moving. But an aircraft with a heavy engine might not even take off. Of all commercially manufactured aircraft engines turbojet engines demonstrate the best power density. However, its best performance can be achieved only at very high speeds, and that demands very high production standards, thus increasing the cost of production. Gas turbine or turboshaft engines are rather heavy, as they not only operate the turbine compressor, but also the reduction gear, which is absolutely necessary but is of considerable weight. These engines are also very expensive, though having some advantages: they are more power effective, the range of speed is up to 600 km/h and they can be also mounted on helicopters. However, in the planes of capacity up to 200-250 hp they are out of use because of high cost. This has been and still remains the segment for piston engines.In light aviation the most popular type of engine is a 4-cycle ones. The cycle of the internal combustion engine is a stroke from one blind spot to the other: one cycle corresponds to a 180 - degrees turn of the crankshaft. With a four-stroke cycle, there are two turns of the shaft, with a two-stroke cycle - only one. As for the four-stroke cycle, there is very little difference between Diesel
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and Otto engine types: both present the same four-stroke performance of intake, compression, expansion and exhaust. The case of a two-stroke engine presented a lot of difficulties. There are only compression and expansion phases there, no place for intake and exhaust, though the processes of intake and exhaust are absolutely necessary for the engine performance. That brings about an additional demand for some forced pressurization to make the inlet pressure of the cylinder higher than the atmospheric pressure.
Diesels offer some compelling economic advantages over gasoline engines. They feature better specific fuel consumption - the measure of power output for each pound of fuel consumed. Another benefit of diesels, which run perfectly well on jet-A, one of the most popular aviation fuels, centers on the rising price and uncertain future of aviation gasoline. In Russia gasoline cost and price are the highest, diesel fuel costs less, kerosene is still less expensive. Globally, turbocharged diesel aircraft engines are in high demand, and that trend will only accelerate. But diesels are heavier, they usually require liquid cooling, they're often limited by certification in how high they can operate, and they cost more to build. Still, Diesel engines and gasoline engines belong to the same class of piston engines. And their parameters are not parallel to those of jets.
Anyway, some characteristics of piston aircraft engines and turboprops for aviation can be compared. From a manufacturing and engineering perspective, the reciprocating engines found in piston aircraft are far less complex than their turboprop counterparts. This is primarily due to the high temperatures and forces unique to turboprop engine operation, which must be accommodated both in materials and engine design, increasing the production cost respectively. For this reason, piston aircraft almost always offer a lower cost of entry. While piston engines are indeed a more simple design, turboprop engines have far fewer moving parts and the smooth, vibration - free operation. A turboprop engine typically offers greater reliability and longer time between overhaul (TBO) than a piston aircraft. Airlines can generally log more hours on their turboprops before they need to bring them in for inspection. The typical TBO for a turboprop engine is 3,000 hours while TBO for a piston aircraft is generally 2,000 hours. So the higher upfront cost of a turboprop aircraft may be somewhat offset by lower maintenance costs over time.
The power of a turbine engine almost always allows turboprop aircraft to travel at higher speeds than piston aircraft. And as turboprop aircraft cabins are typically pressurized these planes also commonly fly at higher altitudes. Turboprop aircraft are generally most efficient at altitudes of 20,000 to 30,000 feet and at average speeds of 250 to 300 kn, while piston aircraft, which are typically not pressurized, are usually restricted to altitudes of 12,000 feet or less (unless an oxygen system is used). And as piston engines are less powerful than turboprop engines, piston aircraft speeds are generally limited to about 200 kn. Piston aircraft are generally smaller aircraft, seating no more than six passengers, and are well suited for relatively short missions of 300 miles or less, while turboprops tend to be larger aircraft with greater passenger capacity -and more fuel on-board - and are more likely to be found flying distances of up to 1,000 miles.
The data in the table below allows comparing 3 engines of various design: ASh-62-piston gasoline engine, ACh-30 piston diesel engine, TVD-20 turbo jet engine. Parameters for comparison are: power, fuel consumption, engine capacity, mass of engine.
Cost fuel (rubles/kg) Power Fuel consumption (l/h) Engine capacity
Mass of engine (kg)
ASh-62 90 1000 200 29,81 560
ACh-30 60 1500 225 61,07 1150
TVD-20 39.5 1380 200 380
It seems that because of the nearing ban of aviation gasoline, diesel engines will remain alternative to jet engines. Fuel prices and other expenses can become almost identical. With the jet engine's light weight, jet-equipped aircraft will be able to take additional loading aboard. However, the jet engine will remain much more expensive and more difficult in production and in service. Private planes, light aviation planes for tourism and sport will possibly be limited to the diesel engine. Any commercial usage of aircraft will undoubtedly demand planes powered by jet engines.
References
1. Gunston Bill (1995). Tupolev Aircraft since 1922. Annapolis, MD: Naval Institute Press.
2. Gunston Bill (1986). World Encyclopedia of Aero Engines.Wellingborough: PatrickStephens. p. 154.
3. Pope S. (2013) Diesel Aircraft Engines Revolution. Available at: http://www.flyingmag.com/ aircraft/diesel-aircraft-engines-revolution [09.03.2016].
4. Piston Engine Aircraft vs. Turboprop Engine Aircraft. (2011) Available at: http://www. shorelineaviation.net/news---events/bid/50442/Piston-Engine-Aircraft-vs-Turboprop-Engine-Aircraft [09.03.2016].
© TypnaHOB A. M., 2016
