Brief introduction of л-3 1φ engine

A л-31Ф (Al-31f) structure dual-rotor afterburner thrust range afterburner 12258daN, with 7620daN in the middle. The current production price is $3 million, which is used for Su -27 fighters. A л-31Ф without afterburner was once used as the power device for the space shuttle буран (with 6 people on board) when it was flying in the atmosphere. The improved version is also used in Su -35 and other aircraft. Development: A л-31Ф is an afterburner turbofan engine developed by Lucca Design Bureau from 1976 to 1985. Great difficulties have been encountered in the development. One is overweight. At first, the engine had 20 stages: 4-stage fan, 12-stage high-pressure compressor, 2-stage high-pressure turbine and 2-stage low-pressure turbine. Results The engine was overweight, reaching 1600kg, and the thrust was only 1 1000daN, so it had to be greatly modified. In the improved scheme, the fan is still 4 stages, but the high-pressure compressor is reduced to 9 stages, the high-pressure turbine and the low-pressure turbine are 1, the total number of stages is reduced to 15, and the weight is reduced to 1520kg at 1976, but there are many failures. In order to eliminate the fault, the weight is increased by about 10%. Later, the method of rewarding five months' salary for every weight loss 1kg was adopted, and the weight was reduced by 70 kg, reaching the original weight goal. Second, the turbine efficiency is 4% lower than the design value, and later decided to accept this reality. However, in order to achieve performance, the turbine inlet temperature must be increased from 1350℃ to 1392℃. As a result, the turbine blades cracked, so the cooling channel was improved, and the channel was very complicated. Adopt swirl cooling, adopt new technology and good materials, and add cobalt, nickel, chromium and aluminum coatings on the surface. To this end, five leaders were replaced. During the period from 1976 to 1985, * * * solved 685 difficult problems. In the design of A л-31Ф, * * obtained 128 patents, used 5/Kloc-0 engines, and ran for 22900h, including bench test 16625h and flight test 6275h, A л. Structure and System The air inlet boxes of the air inlet are all titanium structures with 23 inlet guide vanes with variable camber. The leading edge of the guide vane is fixed, the air in the seventh stage of the high-pressure compressor is used for anti-icing, and the rear part is adjustable. The fan is a 4-stage axial flow with a pressure increasing ratio of 3.6. The whole fan is made of titanium. The first three rotor blades have damping bosses. The whole fan rotor is welded into an integral part by electron beam welding. On the shell corresponding to the fourth stage rotor blade, there is an organic shell processing ring cavity with 400 chutes to improve the stable working margin of the fan. The fourth stage outlet rectifier blades are double rows of cascade in series. 9-stage axial flow of high-pressure compressor. 1 ~ 3 discs are welded together by electron beam, and 4 ~ 6 discs are also welded into a whole by electron beam. The grades 7 to 9 are single disks, and the grades 6 disks are connected by long bolts. 1 ~ 6 grade discs are titanium alloys, and grades 7 ~ 9 are heat-resistant alloys. 1 ~ 5 rotor blades are made of titanium alloy, and 6 ~ 9 rotor blades are made of heat-resistant alloy. All Grade 9 tenons are annular dovetail tenons. The inlet deflector and the 1 class deflector are both made of titanium alloy and installed on the front shell made of titanium alloy. The intake deflector and 1 ~ 2 stage deflector are adjustable in three rows. The 1 ~ 8 stage deflector is cantilever structure, and the outlet deflector is also double-row cascade. The combustion chamber is annular. There are 28 dual-oil centrifugal nozzles, two ignition devices and semiconductor electric nozzles. The high-pressure and low-pressure turbines of the runner are single-stage. The high-pressure turbine guide has 14 groups, with 3 blades in each group. 90 HP turbine rotor blade * * *, without crown, with damper at tenon. Low pressure turbine guide *** 1 1 group, each group also has 3 blades. There are also 90 rotor blades with crowns. The low-pressure turbine shaft is characterized in that the front and rear sections are divided into three sections, the front and rear sections are made of heat-resistant stainless steel, and the middle section is made of titanium alloy, and the three sections are connected into a whole by radial pins with fork structure. The four rows of blades of HP and LP turbines are all air-cooled blades, and the total amount of cold air accounts for 17.5% of the internal air flow, of which 7.5% is directly introduced from the secondary air flow, which mainly cools the leading edge of the HP turbine guide, and the other air flow is 8.9%, which is led out from the outer wall of the combustion chamber casing and cooled by the air-to-air heat exchanger arranged in the external bypass channel. The cooling air temperature 125 ~ 2 10℃ can be reduced. Among these air, 6.4% of the internal airflow enters through the middle cavity of the high-pressure guide vane, 4.6% enters the front of the high-pressure scroll, and 3.2% is used to cool the high-pressure turbine rotor blades. Low-pressure turbine rotor blades are cooled by external duct air. Cold air is introduced into the interior through the support plate of the turbine back shell, pressurized by the pump action of some radial inclined holes on the low-pressure turbine disk, and then enters the low-pressure turbine blades. There is a mixer at the entrance of the afterburner, which supplies oil in five zones, of which the fifth zone is the starting zone of the afterburner, which is ignited by "hot jet". The flame stabilizer has three V-shaped stabilizers and some radial flame transmission grooves. The anti-vibration measures are full-length anti-vibration net, and a large number of anti-vibration holes are opened at the inner tail cone. Tail nozzle convergent-divergent nozzle, each nozzle has 16 regulating blades and sealing blades. The convergent nozzle is controlled by 16 hydraulic actuator, and the divergent nozzle is fastened by an annular "belt" formed by 16 circumferential pneumatic actuator. With the change of pressure drop ratio of nozzle, the outlet cross-sectional area of nozzle changes due to pneumatic driving. The basic part of the control system is a mechanical-hydraulic system, including main pump-main regulator, afterburner pump, afterburner oil supply and nozzle control. It also has an analog electronic control device called integrated controller, which controls the limit value of the main working state of the engine and many other functions. When the electronic system fails, the automatic conversion is controlled by the mechanical-hydraulic system. It also has many parameters monitoring systems, as well as the special anti-surge system and turbine cooling gas control system of the former Soviet engine. A л-31Ф (Al-31f)-Content selection-Development overview, technical data of structure and system, technical data, maximum afterburner thrust (daN) 12258 intermediate thrust (daN) 7620 afterburner fuel consumption [kg/(Dan Kloc-0/4 1300 Length (mm) 4950 Mass (kg) 1530 (according to the standards of the former Soviet Union) 1750 (according to international general regulations)