An aviation turbofan engine and an external duct nozzle

Abstract

The present invention relates to the technical field of aviation turbofan engines, and provides an aviation turbofan engine and an external ducted nozzle. A notch is provided at the trailing edge of the engine nacelle on the outside of the engine pylon, and a guide curved surface is provided on the external ducted nozzle profile that matches the shape of the notch. The notch is provided on one side of the outside of the engine pylon, and the transition section between the notch and the trailing edge of the engine nacelle includes two transition fillets. The present invention utilizes a single-sided notch-shaped nozzle in the turbofan engine's external duct, utilizing the high-speed flow of the engine fan exhaust to provide flow protection for the wing, improving the lift coefficient and reducing the adverse effects of the nacelle on the wing at high angles of attack. This reduces drag, reduces nacelle weight, and improves the aircraft's lift coefficient and lift-to-drag ratio. The present invention has the potential to replace the function of external nacelle spoilers, offering low drag and no weight penalty, and can improve the performance and economy of commercial aircraft products, thereby enhancing product competitiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation turbofan engines, and in particular to an aviation turbofan engine and an external duct nozzle. Background Art

[0002] Currently, most civil airliners use high-bypass-ratio turbofan engines as propulsion systems. To achieve higher propulsion efficiency and better fuel economy, modern commercial aircraft engines are adopting increasingly larger bypass ratios and larger sizes, which negatively impacts both the aerodynamic and structural design of the wings. In terms of aerodynamic design, the increased wetted area of the nacelle increases the aircraft's frictional resistance. At low speeds and high angles of attack, the nacelle significantly blocks the incoming airflow from the wing, easily causing flow separation and lift loss.

[0003] To address the adverse effects of increased nacelle size on the wings, nacelle spoilers are often used to provide wing flow protection. These can, to a certain extent, compensate for the nacelle's airflow shielding of the wing. However, the inner side of the nacelle, where the wing merges with the body, experiences higher airflow velocities, making nacelle spoilers more effective. However, the outer side is less effective. Furthermore, nacelle spoilers generate significant drag, increasing aircraft weight and reducing economic efficiency. Summary of the Invention

[0004] The purpose of the present invention is to overcome at least one of the shortcomings of the prior art and to provide an aviation turbofan engine and an external duct nozzle that can utilize the high-speed flow of the engine fan exhaust to provide flow protection for the wings, improve the lift coefficient, and reduce the adverse effects of the engine nacelle on the wings at large angles of attack.

[0005] The present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides an external duct nozzle of an aviation turbofan engine, wherein a notch is provided at the trailing edge of the engine nacelle outside the engine suspension, and a guide surface matching the shape of the notch is provided on the external duct nozzle profile.

[0007] In any of the possible implementations described above, there is further provided an implementation in which the notch is provided on a single side outside the engine pylon, and the transition between the notch and the trailing edge of the engine nacelle includes two transition fillets. The transition fillets serve to stabilize the jet flow and prevent the generation of excessive separation vortices and aerodynamic noise. The fillet should generally not exceed 90°, and the proportion of the fillet should not exceed 50% of the notch width.

[0008] As for any possible implementation described above, there is further provided an implementation, wherein the notch is provided within a range of 0° to 90° in a circumferential direction on the outer side of the engine suspension.

[0009] Any possible implementation as described above further provides an implementation, wherein the guide surface transitions smoothly with the outer duct profile, and has one or more sections of guide surface control lines; the guide surface is configured by multiple sections of bridging surfaces, and the bridging surface maintains curvature continuity with the inner surface of the engine outer duct, and the length of the bridging surface does not exceed 50% of the width of the notch to avoid excessively affecting the shape of the inner duct nozzle, and the specific profile shape needs to be determined by aerodynamic optimization design.

[0010] The function of the guide surface control line is to complete the nacelle airfoil so that the nacelle airfoil after adding the notch design can maintain a low-resistance streamline shape, thereby reducing the aerodynamic resistance cost brought by the device.

[0011] As for any possible implementation described above, there is further provided an implementation, wherein the outer duct nozzle is formed integrally with the outer surface of the engine nacelle.

[0012] As for any possible implementation described above, an implementation is further provided, wherein the notch includes an arc segment and a connecting segment, the arc segment and the connecting segment are connected by a first transition fillet, the connecting segment is connected to the trailing edge of the engine nacelle by a second transition fillet, and both the first transition fillet and the second transition fillet do not exceed 90°.

[0013] Any possible implementation as described above, further provides an implementation, wherein the depth of the notch does not exceed 20% of the aerodynamic chord length of the engine nacelle and is not less than 5% of the aerodynamic chord length of the engine nacelle; the width of the notch does not exceed 1 / 4 of the circumference of the trailing edge of the engine nacelle and is not less than 1 / 20 of the circumference of the trailing edge of the engine nacelle.

[0014] As for any possible implementation described above, there is further provided an implementation, wherein the arc segment does not exceed 50% of the notch width.

[0015] On the other hand, the present invention also provides an aviation turbofan engine, which has the above-mentioned external duct nozzle of the aviation turbofan engine.

[0016] Furthermore, the lift coefficient of the aviation turbofan engine is increased by 1%-2%.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention adopts a single-sided notch-shaped nozzle on the outer duct of the turbofan engine, utilizing the high-speed flow of the engine fan exhaust to provide flow protection for the wing, thereby improving the lift coefficient and reducing the adverse effects of the engine nacelle on the wing at high angles of attack, thereby reducing drag and nacelle weight, and improving the aircraft's lift coefficient and lift-to-drag ratio.

[0019] 2. The principle of this invention is different from that of nacelle spoilers and has the potential to replace the function of outer nacelle spoilers. It has low drag, no weight penalty, and can improve the performance and economy of commercial aircraft products, thereby enhancing product competitiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Shown is an axial profile view of an external bypass nozzle of an aviation turbofan engine according to an embodiment of the present invention.

[0021] Figure 2 Shown is a side view of the bypass nozzle of an aviation turbofan engine in an embodiment.

[0022] Figure 3 The figure shows a schematic diagram of the guide surface in the embodiment (the perspective is looking outward from the outer duct of the transmitter).

[0023] Figure 4 Shown is a diagram showing the lift-enhancing effect of a civil passenger aircraft equipped with an aviation turbofan engine according to an embodiment of the present invention.

[0024] In the figure: 1-engine nacelle; 2-engine pylon; 3-notch; 4-trailing edge of engine nacelle; 5-first transition fillet; 6-second transition fillet; 7-guiding surface; 8-guiding surface control line. DETAILED DESCRIPTION

[0025] The following will describe in detail specific embodiments of the present invention in conjunction with specific drawings. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation; they can be combined with each other to achieve better technical effects. In the drawings of the following embodiments, the same reference numerals appearing in each drawing represent the same features or components, which can be applied to different embodiments.

[0026] The embodiment of the present invention provides an external duct nozzle for an aviation turbofan engine, wherein a notch-shaped trailing edge is designed at the trailing edge of the engine nacelle and outside the engine pylon. A guide curved surface is designed on the external duct nozzle profile to match the notch shape.

[0027] In a specific embodiment, an external bypass nozzle of an aviation turbofan engine is as follows Figure 1As shown. This invention is a new ducted nozzle design featuring a notch-shaped nozzle on the outside of the engine pylon 2. The notch 3 is integrated with the engine nacelle 1 and positioned close to the engine pylon 2, unilaterally on the outside of the pylon 2. Preferably, the depth of the notch 3 is no more than 20% of the nacelle's aerodynamic chord length and no less than 5% of the nacelle's aerodynamic chord length; the width of the notch is no more than 1 / 4 of the nacelle's trailing edge circumference and no less than 1 / 20 of the nacelle's trailing edge circumference. Further optimization is achieved by notch 3 having a depth no more than 10% of the nacelle's aerodynamic chord length and a width no more than 1 / 6 of the nacelle's trailing edge circumference.

[0028] The transition between notch 3 and the nacelle trailing edge 4 has two radii: the first radii 5 and the second radii 6 shown in the figure. These radii are intended to stabilize the jet flow and prevent excessive separation vortices and aerodynamic noise. They should not exceed 90°, and the arc ratio should not exceed 50% of the notch width.

[0029] The main components of the present invention are integrated with the nacelle shape and the engine inner channel curved surface through an integrated design, and the notched nozzle has a fixed shape and has no movement relationship.

[0030] like Figure 2 As shown, the notch nozzle is installed outside the engine nacelle pylon 2, and the notch 3 is located near the engine nacelle 1, located on the upper part of the engine nacelle 1; the notch nozzle and the engine nacelle trailing edge 4 are transitioned by fillets at both ends; the nozzle notch 3 and the outer surface of the engine nacelle 1 are designed as an integrated whole; the outer duct nozzle surface is designed with a guide surface 7 that matches the shape of the notch 3. The design of the guide surface 7 is as follows Figure 3 As shown, the guide surface 7 is shaped to match the notched nozzle and smoothly transitions with the outer duct profile. It has one or more guide surface control lines 8. The first chamfer of the guide surface 7 corresponds to the first transition fillet 5 of the notched nozzle; the second chamfer of the guide surface corresponds to the second transition fillet 6 of the notched nozzle.

[0031] The guide surface 7 is configured by multiple sections of bridging surfaces. The bridging surface maintains curvature continuity with the inner surface of the engine outer duct. The length of the bridging surface should not exceed 50% of the width of the gap 3 to avoid excessively affecting the shape of the inner duct nozzle. The specific surface shape needs to be determined by aerodynamic optimization design.

[0032] The function of the guide surface control line 8 is to complete the nacelle airfoil so that the nacelle airfoil after adding the notch design can maintain a low-resistance streamline shape, thereby reducing the aerodynamic drag cost.

[0033] The notched nozzle and its corresponding guide surface 7 can lead out a portion of the high-energy flow of the outer duct to the outside, charging the local flow on the upper surface of the wing, thereby providing a certain flow protection for the leading edge of the wing under the condition of large angle of attack of the aircraft, and can improve the adverse flow interference caused by the large-size nacelle on the wing, thereby improving the lift coefficient and aerodynamic efficiency of the entire aircraft.

[0034] Since the notch 3 penetrates the nacelle outer duct, if it penetrates directly, the thickness of the trailing edge at the notch 3 will be greater than the thickness of the rest of the nacelle trailing edge 4. To ensure the uniform thickness of the nacelle trailing edge 4, it is necessary to make the cutout size of the nacelle inner profile larger than the notch size of the nacelle outer profile. Then, by adding the guide curved surface 7, the nacelle trailing edge 4 at the notch 3 is quickly contracted so that the thickness of the trailing edge at the notch 3 is roughly equal to that of the rest of the nacelle trailing edge 4.

[0035] like Figure 4 As shown in the figure, analysis results show that under takeoff conditions (inflow Mach number of approximately 0.2), the bypass nozzle of the aviation turbofan engine of the present invention can increase the lift coefficient of a civil passenger aircraft by approximately 0.01-0.02. Considering the maximum takeoff weight of large passenger aircraft of 200-300 tons, this device can increase the aircraft's payload by approximately 1-2 tons, which is a very considerable economic benefit.

[0036] The innovation of the present invention is:

[0037] 1. The functional implementation principle of the present invention is different from that of nacelle spoilers. It mainly controls the jet energy distribution in the key area to achieve flow protection of the wing leading edge, thus avoiding adverse aerodynamic interference between the inner and outer nacelle spoilers;

[0038] 2. The present invention can provide flow protection for the wing while achieving rent and weight reduction. Compared with nacelle spoilers, it has obvious drag and weight advantages.

[0039] 3. The present invention can be designed and manufactured in an integrated manner with the nacelle, avoiding additional structural components and additional mechanical connections, which is beneficial to improving the maintainability of the equipment and reducing costs.

[0040] 4. The design shape of the outer duct guide surface and the geometric feature that the size of the inner surface cut of the nacelle is slightly larger than the outer surface cut.

[0041] 5. The inner surface of the nacelle extends from the inner profile to the trailing edge, and the surface maintains a smooth transition geometric feature.

[0042] Although several embodiments of the present invention have been described herein, those skilled in the art will appreciate that modifications may be made to the embodiments herein without departing from the spirit of the present invention. The above embodiments are merely exemplary and should not be used as limitations on the scope of the present invention.

Claims

1. An external bypass nozzle of an aviation turbofan engine, characterized in that: The outer duct nozzle is provided with a notch at the rear edge of the engine nacelle outside the engine suspension, and a guide curved surface matching the shape of the notch is provided on the outer duct nozzle profile; The guide curved surface smoothly transitions with the outer duct profile and has one or more guide curved surface control lines; the guide curved surface includes a multi-segment bridge curved surface configuration, the bridge curved surface maintains curvature continuity with the inner curved surface of the engine outer duct, and the length of the bridge curved surface does not exceed 50% of the width of the gap; The depth of the notch shall not exceed 20% of the aerodynamic chord length of the engine nacelle and shall not be less than 5% of the aerodynamic chord length of the engine nacelle; the width of the notch shall not exceed 1 / 4 of the circumference of the trailing edge of the engine nacelle and shall not be less than 1 / 20 of the circumference of the trailing edge of the engine nacelle; The notch is arranged within a range of 0° to 90° in the circumferential direction of the outer side of the engine suspension.

2. The bypass nozzle of the aviation turbofan engine according to claim 1, characterized in that: The notch is arranged on one side of the outer side of the engine suspension, and the transition section between the notch and the trailing edge of the engine nacelle includes two transition fillets.

3. The bypass nozzle of the aviation turbofan engine according to claim 1, characterized in that: The outer duct nozzle is formed integrally with the outer surface of the engine nacelle.

4. The bypass nozzle of the aviation turbofan engine according to claim 1, characterized in that: The notch includes an arc segment and a connecting segment, the arc segment and the connecting segment are connected by a first transition fillet, the connecting segment is connected to the trailing edge of the engine nacelle by a second transition fillet, and both the first transition fillet and the second transition fillet do not exceed 90°.

5. The bypass nozzle of the aviation turbofan engine according to claim 4, characterized in that: The arc segment does not exceed 50% of the width of the gap.

6. An aviation turbofan engine, characterized in that: The aviation turbofan engine has an external bypass nozzle of the aviation turbofan engine as described in any one of claims 1 to 5.

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