A non-regulated air intake of a supersonic civil aircraft

Abstract

The utility model relates to the field of aviation engineering and can be used to improve the efficiency and gas-dynamic stability of the power plant of a supersonic civil aircraft. A fixed air intake of a supersonic civil aircraft comprises a teardrop-shaped entrance and throat, an inlet section, a channel, and a boundary layer control system in the form of a transverse suction slit and an undercut at the top of the inlet section. The inlet section of the air intake consists of two successively arranged stages of the braking surface: the first and second, wherein the first stage of the braking surface has the shape of a dihedral angle with a rounded angle at the apex and an equivalent wedging angle relative to the direction of the incoming flow of δ = 4°...6°, and the second stage of the braking surface of the air intake is based on the flow surface of a spatial conical flow,realized during flow around a right circular cone by a supersonic flow with a calculated Mach number, the tangents to the generatrices of the second stage of the braking surface at its beginning and end form angles with the direction of the incoming flow of δ2 = 6°…13° and δ3 = 7°…21°, respectively, the second stage of the braking surface smoothly transitions into the surface of the air intake channel, the throat of which has a teardrop shape, the area of ​​the undercut part of the surface of the inlet section of the air intake is Fundercut = 20% - 35% of the area of ​​the inlet of the air intake, and the transverse suction slot of the boundary layer control system is located in the lower part of the air intake channel in the throat area.

Description

[0001] The utility model relates to the field of aviation technology and can be used to improve the efficiency and gas-dynamic stability of the power plant of a supersonic civil aircraft.

[0002] It is well known that the development of a modern civil supersonic aircraft must take into account the requirements for low sonic boom levels generated during supersonic flight. This requirement significantly determines the external contours and the choice of powerplant layout for the prospective aircraft. In particular, over-the-wing and over-the-fuselage configurations are being considered, which reduce the intensity of the aircraft's sonic boom by shielding disturbances from the supersonic air intake with the fuselage or wing surface. However, with this configuration, the air intakes operate in unfavorable conditions of accelerated flow and a thickened boundary layer, which complicates ensuring gas-dynamic stability within the aircraft's operational flight envelope.

[0003] The air intake described in the patent "Supersonic Aircraft" RU 136012 dated 04.06.2013 is known. The main drawback of the air intake is the lack of a well-developed boundary layer control system in the air intake duct, which does not ensure gas-dynamic stability of the power plant under supersonic cruising flight conditions.

[0004] A known air intake is described in patent RU 149896, "Air Inlet with Variable Geometry for a Supersonic Aircraft," dated August 7, 2014. This solution is an air intake with an adjustable throat for a supersonic aircraft, comprising a spatial wedge, a cowl, sidewalls, a boundary layer bleed system, and an air intake throat with a subsonic diffuser. The air intake is mounted on the aircraft body and has swept-back leading edges. The disadvantages of this solution include variable geometry, as the implementation of this technology leads to significant complexity and weight increases in the design. The described air intake also has an angular shape of the entrance and throat, which complicates the smooth connection of the air intake channel with the engine and can potentially lead to the occurrence of separated flows in the air intake channel and, accordingly, to a deterioration in its characteristics.Another disadvantage of this solution is the presence of undercut surfaces in the air intake, which, when flowing around them in supersonic flight modes, can cause separated flows, which leads to a violation of the gas-dynamic stability of the power plant.

[0005] Air intakes used in overwing configurations of advanced supersonic civil aircraft are known, described in patents "Supersonic Civil Aircraft" No. RU 196109 dated November 25, 2019 and "Supersonic Civil Aircraft" No. RU 196128 dated November 25, 2019. The main drawback of these intakes is the lack of a boundary layer control system, which is necessary to ensure the gas-dynamic stability of the power plant at supersonic flight modes. Furthermore, the presented air intakes are inverse, that is, oriented such that the shock waves arising at the air intake inlet hit the surface of the aircraft fuselage. This can also lead to a violation of the gas-dynamic stability of the power plant in this configuration at supersonic flight speeds.

[0006] Another overwing fixed air intake is known, described in patent "Supersonic Aircraft" No. RU 2753443 dated December 29, 2020. The air intake is designed with a fixed compression wedge angle of 1°...9°, has the shape of an unequal trapezoid, is mounted above the wing extension, and is adjacent to the side of the fuselage. This air intake contains a sophisticated boundary layer control system in the throat area, consisting of slots and perforations that bypass excess internal pressure. The air intake is mounted on the wing and fuselage boundary layer bleed wedges, with an air intake channel for purging the engine components located in the space between them. The disadvantages of the air intake include the fact that the air intake has an angular shape of the entrance and throat, which complicates the smooth connection of the channel with the engine and can lead to the occurrence of separated flows in the channel and, consequently, to a deterioration in the characteristics of the air intake.Another drawback of the air intake is the insufficient efficiency of the proposed version of the boundary layer control system, which does not ensure a sufficient degree of gas-dynamic stability of the power plant during supersonic flight modes.

[0007] The prototype is an overwing spatial air intake described in patent No. RU 2835245 dated February 24, 2025, "Air Inlet for a Supersonic Civil Aircraft." The air intake has a three-dimensional braking surface with a fixed angle of 4° to 13°. Viewed from the front, the air intake inlet has a teardrop shape, which ensures its mating with the wing and fuselage surfaces at the location where it is located. The camber angle of the air intake braking surface generators is 100° to 150°. The air intake is equipped with an advanced boundary layer control system, including a transverse slot in the throat, a side air bypass window into the external flow, and a trimmed upper surface of the cowling. The total flow area of ​​the boundary layer control systems is 16% to 35% of the air intake inlet area.The prototype's shortcomings include an insufficient value of the total pressure recovery coefficient ν, as well as insufficient gas-dynamic stability at supersonic Mach numbers.

[0008] The objective and technical result of this utility model is to ensure high efficiency and gas-dynamic stability of the operation of the power plant of a supersonic civil aircraft under all operational flight modes.

[0009] The technical result is achieved in that the unregulated air intake of a supersonic civil aircraft contains an entrance and a throat of a teardrop shape, an inlet section, a channel and a boundary layer control system in the form of a transverse suction slit and a trimming of the upper part of the inlet section.The inlet section of the air intake consists of two successively located stages of the braking surface: the first and the second, wherein the first stage of the braking surface has the shape of a dihedral angle with a rounded angle at the apex and an equivalent wedging angle relative to the direction of the oncoming flow δ = 4°…6°, and the second stage of the braking surface of the air intake is constructed on the basis of the surface of the flow of a spatial conical flow, realized during flow around a right circular cone by a supersonic flow with a calculated Mach number, the tangents to the generators of the second stage of the braking surface at its beginning and end make angles with the direction of the oncoming flow δ2= 6°…13° and δ3= 7°…21°, respectively, the second stage of the braking surface smoothly transitions into the surface of the air intake channel, the throat of which has a teardrop shape, the area of ​​the cut part of the surface of the inlet section of the air intake is F. подрез= 20% - 35% of the air intake inlet area, and the boundary layer control system's transverse suction slot is located at the bottom of the air intake channel in the throat area.

[0010] The sharp corners of the neck in the cross section are smoothed by inscribed circles with radii R1 = 0.2…0.3D ДВ and R2= 0.02…0.08D ДВ , where D ДВ – diameter of the engine inlet.

[0011] The essence of the utility model is explained by the following illustrations.

[0012] Fig. 1 - General diagram of the air intake from the side view.

[0013] Fig. 2 - Diagram of the air intake inlet section.

[0014] Fig. 3 - Diagram of the air intake throat when viewed from the front.

[0015] The general diagram of the air intake in the side view, shown in Fig. 1 includes the inlet section - 1, the throat - 2, and the channel - 3, designed to supply air to the engine inlet - 4. The air intake inlet is a figure limited by the leading edges of the inlet section, and the throat of the air intake in the front view have a teardrop shape. The inlet section of the air intake consists of two successively located stages of the braking surface: the first - 5 and the second - 6 (Fig. 2). The first stage of the braking surface has the shape of a dihedral angle with a rounded angle at the apex and an equivalent wedging angle relative to the direction of the oncoming flow δ = 4°…6°.The second stage of the air inlet braking surface is constructed based on the flow surface of a spatial conical flow, realized during supersonic flow with a calculated Mach number around a right circular cone. The tangents to the generatrices of the second stage of the braking surface at its beginning and end form angles with the direction of the incoming flow of δ2 = 6°…13° and δ3 = 7°…21°, respectively. At supersonic flight modes, flow compression in the air inlet with the described braking surface is realized in a system of three compression shocks: a flat oblique shock generated by the first braking stage, a conical shock generated by the second braking stage, and a closing shock.As a result, at supersonic flight conditions, the air intake with this braking surface has a significantly higher total pressure recovery coefficient than, for example, an air intake with a single-stage braking surface, which was used as a prototype. This ensures high efficiency and gas-dynamic stability of the supersonic civil aircraft's power plant, especially at supersonic flight conditions.

[0016] The second-stage braking surface smoothly transitions into the air intake channel surface, the area of ​​which gradually expands from the throat section to the engine section. The length of the air intake channel is L К = 3…5D ДВ , where D ДВ – the diameter of the engine inlet. When viewed from the front, the air intake has a teardrop-shaped inlet and throat (Fig. 3). The sharp corners of the throat in cross section are smoothed by inscribed circles with radii R1 = 0.2…0.3D ДВand R2= 0.02…0.08D ДВ The teardrop-shaped air intake inlet simplifies placement of the air intake at the wing-fuselage junction, while also simplifying the transition from the throat to the engine section within the air intake duct. As a result, uninterrupted flow around the air intake duct is ensured across a wide range of flight conditions, resulting in high efficiency and gas-dynamic stability for the supersonic civil aircraft's powerplant under all operating conditions.

[0017] The air intake is equipped with a boundary layer control system (Fig. 2). The boundary layer control system includes two elements: a cut-off of the upper part of the inlet section - 7 (Fig. 2), made in the upper part of the inlet section of the air intake, and a transverse boundary layer suction slot - 8 (Fig. 2), located in the lower part of the air intake in the throat area. The total area of ​​the cut-off surface of the inlet section of the air intake corresponds to F подрез = 20% - 35% of the air intake inlet area, and the suction gap passage area is F отс = 15% - 25% of the air intake inlet area. The boundary layer control system ensures uninterrupted flow around the inlet section and air intake duct, as well as sufficient anti-surge reserve of the air intake over a wide range of engine operating conditions.

[0018] Thus, as a result of applying the set of measures described above, a technical result is achieved, namely: high efficiency and gas-dynamic stability of the operation of the power plant of a supersonic civil aircraft is ensured throughout the entire operational range of flight modes.

Claims

1. A non-adjustable air intake for a supersonic civil aircraft, comprising an inlet and a teardrop-shaped throat, an inlet section, a channel and a boundary layer control system in the form of a transverse suction slot and an undercut at the top of the inlet section, characterized in that the inlet section of the air intake consists of two successively arranged stages of the braking surface: the first and the second, wherein the first stage of the braking surface has the shape of a dihedral angle with a rounded angle at the apex and an equivalent wedging angle relative to the direction of the incoming flow δ = 4°…6°, and the second stage of the braking surface of the air intake is constructed on the basis of the flow surface of a spatial conical flow, realized when a supersonic flow with a calculated Mach number flows around a right circular cone,the tangents to the generators of the second stage of the braking surface at its beginning and end form angles with the direction of the oncoming flow δ2= 6°…13° and δ3= 7°…21°, respectively, the second stage of the braking surface smoothly transitions into the surface of the air intake channel, the throat of which has a teardrop shape, the area of ​​the cut part of the surface of the inlet section of the air intake is F, подрез = 20% - 35% of the air intake inlet area, and the boundary layer control system's transverse suction slot is located at the bottom of the air intake channel in the throat area.

2. A non-adjustable air intake according to paragraph 1, characterized in that the sharp corners of the throat in the cross-section are smoothed by inscribed circles with radii R1 = 0.2…0.3D ДВ and R2= 0.02…0.08D ДВ , where D ДВ - engine inlet diameter.

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