The plate cutter ( English Splitter plate ) - the dividing wall between the air intake and the fuselage , mounted on jet aircraft . The resulting gap is used to divert the boundary layer growing on the fuselage from the air intakes.
Boundary layer management
The main disadvantages of the side air intakes are the shading of one of them with the fuselage during gliding maneuvers at supersonic flight speeds and the effect of the boundary layer on their work, which is the main source of velocity field unevenness in the air intake and air channel. The boundary layer occurs as a result of viscous friction of the air flow on the streamlined surfaces of the aircraft, and the flow velocity at the skin drops sharply to zero. During supersonic flow around, shock waves interacting with the boundary layer cause local separation of the flow from the streamlined surface with a sharp increase in the thickness of the boundary layer. The uneven distribution of speed due to the boundary layer increases so significantly that, for example, in an airplane with air intakes directly adjacent to the fuselage skin, thrust decreases and the specific fuel consumption increases.
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 impairing the braking effect of the flow and causing a decrease in effective engine thrust . To combat this phenomenon, boundary layer control systems are used, which usually include systems for suctioning or draining the boundary layer.
Often the cutter has a perforation through which its own boundary layer is removed.
See also
- Air intake control system
- Supersonic air intake
- Diffuser (car)
- Air intake cone
Notes
- Hughes, Donald L; Holztman, Jon K; Johnson, Harold J. Flight-Determined Characteristics of an Air Intake System of an F-111A Airplane (Eng.) // Technical Note: journal. - National Aeronautics and Space Administration . - Vol. D — 6679 .
- Hünecke, Klaus. Jet Engines - England: Airlife, 1997. - P. 76–79. - "... the thickening of the boundary layer that develops at high angles-of-attack along the lower side of the fuselage forebody [in the F-16]. In order to prevent low-energy flow from entering the engine, the intake had to be offset from the fuselage to free it from the boundary layer, which uninterruptedly passes along the fuselage. “The intake cowl [of the F-16] features a moderately blunt lower lip that transitions into a sharp leading-edge extension or splitter plate on the upper side (close to the fuselage).” - ISBN 1853108340 .