X Международная студенческая научная конференция Студенческий научный форум - 2018

Our scientific effort is devoted to the engine AL-31F, so in this article we would like to present the most important information about it.

AL-31F is a high-temperature turbojet bypass augmented engine. It was designed by A.M. Lyulka. AL stands for the first letters of the name and the surname – Arhip Lyulka, 31 means the model, F means that the engine is equipped with a thrust augmentor.

The engine design began in 1973, the first testing was carried out in 1977, and the state level testing was in 1986.

After the death of Arhip Lyulka in 1984, modification and further development of the engine was under control of the general designer V.M. Chepkin.

Designed more than forty years ago for the fourth generation fighters, AL-31F is still the best in its class by the specifications. The technical reserve and its structure make it a constantly retrofittable engine, which made it possible to use the accumulated experience in the creation of this model range for the development of a fundamentally new engine for the fifth generation fighters.

AL-31F manufactured by Moscow Machine-Building Plant "Saturn" was chosen as the main engine for the fourth generation fighter Su-27, whose primary task was to gain air superiority over its American counterpart F-15. Currently the engine family AL-31F and its derivatives power most aircraft, produced by Sukhoi Design Bureau, including Su-27, its modifications (for example Su-30), front-line bomber Su-34, and the new perspective aviation complex of front-line aviation T-50 (Su-57).

Unfortunately, the power characteristics of AL-31F do not completely satisfy the parameters of the technical specifications for the aircraft of the Su family, which should be in service in the Russian Air Force. It is primarily about the new front-line production bombers Su-34 and deeply modernized multifunctional Su-27SM fighters. In the future, new Su-57 modernized AL-31F engines are planned to be powered by modernized AL-31F engines, which must satisfy the new standards requirements.

AL-31F is a highly efficient, economical, high-temperature turbojet bypass augmented engine incorporating a two-spool compressor, a heat exchanger of the turbine cooling system, mixing of secondary and primary airflows after the turbine, an augmentor, a supersonic adjustable exhaust nozzle and modular structure.

This engine operates in a wide range of altitudes and flight speeds, works steadily on the modes of deep surge of an air intake at Mach 2, and also in conditions of flat and inverted spin, and it provides unique maneuvering aircraft capabilities.

The engine consists of a four-stage low-pressure compressor with an adjustable inlet assembly, an intermediate housing with a central drive box, a 0-stage high-pressure compressor, with a variable angle of the inlet blades of the first stage, and a directing device of the first two stages, a combustion chamber, an air-to-air heat exchanger in the turbine cooling system, a single-stage cooled low-pressure turbine, a single-stage cooling high-pressure turbine, an afterburner with mixing of primary and secondary airflow, a supersonic jet nozzle, a gearbox and accessories at the top part of the engine.

The engine develops a booster thrust of 12,500 kgf in the mode of "full afterburner" and 7700 kgf in the "maximum" mode. Specific fuel consumption is 0.67 kg (kgf / h). High-pressure two-stage compressor provides 23 times compression of incoming air at a flow rate of 112kg / s and a bypass ratio of about 0.56.

In conclusion we would like to emphasize that the AL-31F engine became a real technical breakthrough, largely determining the future development of aircraft engines. Created more than forty years ago, AL-31F, still meets the technical requirements of the best samples in its class. This engine family has become one of the most important factors of air superiority of the Russian Air Force.

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