Supersonic air intake - jet engine air intake designed to operate at supersonic free air speeds . This is a carefully designed and manufactured structure, on the performance of which depends on the reliability of the aircraft engine and its achievement of the required characteristics in all operational flight conditions.
The air flow entering the compressor input of the engine during supersonic flight must be braked to subsonic values, which is required by the conditions of reliable engine operation. This is achieved by the shape of the air intake, the relatively large length of the air channel (relative to the in / intakes of the subsonic vehicles) and the presence of special devices for braking the flow.
In addition, the throughput of the air intake duct must correspond to the required air flow rate in the engine at the current time, depending on the engine operating mode, which requires the installation of technically sophisticated automatic devices that regulate the throughput of the inlet device. Usually used deflected vertical ( Tu-22M 2) or horizontal "wedge" ( MiG-25 ) or extendable "cone" ( MiG-21 ).
Also, at high flight speeds, a low-energy boundary layer accumulates on the surfaces of the aircraft in front of the air intake, penetrating the air intake and worsening the flow braking efficiency, which is further aggravated by the aircraft’s maneuvers. This factor does not occur if the input device is in the unperturbed flow zone, for example, in front of the fuselage. But with the lower, and especially the lateral arrangement of the air intakes, their input devices have to be removed from the fuselage, forming a gap for the removal of the boundary layer growing on the fuselage, and dividing partitions - plate-type cutoffs are often also installed.
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DSI Intake
The modern development of supersonic air intakes is the DSI air intake ( English diverterless supersonic inlet), i.e., it does not have a plate-like cutoff of the boundary layer and internal movable control elements. This design made it possible to solve several problems at once: shielding the compressor blades, retracting the boundary layer , increasing the recovery coefficient of the total pressure. The absence of a gap for draining the boundary layer reduces the visibility of the aircraft and its aerodynamic drag . Such an air intake is technically simpler and lighter.
The DSI air intake consists of a ramp that compresses the flow and forms a conical flow, as well as edges of a special shape that create a fan of compression waves and, in interaction with the ramp, unfold the low-energy part of the boundary layer to the outside, preventing it from entering the air intake.
Work on the DSI air intake was first carried out at Lockheed Martin in the early 1990s . The first flight of the F-16 aircraft with a DSI air intake was made on December 11, 1996 .
Aircraft with DSI Intake
- Lockheed Martin F-35 Lightning II
- Chengdu J-10B
- Chengdu J-20
- Shenyang J-31
- Jf-17 thunder
Examples of supersonic airplanes with uncontrolled air intake
- MiG-19 (1452 km / h at an altitude of 10,000 m)
- Tu-22 (max. 1550—1610 km / h)
- MiG-27 (max. 1885 km / h at an altitude of 8000 m)