Dual-bearing rotating vector nozzle based on non-axisymmetric Laval nozzle and its design method

Abstract

This invention discloses a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle and its design method. The dual-bearing rotating vector nozzle includes: a straight section A of the nozzle, a first rotating section B, a second rotating section C, and bearings D and E connected to these three sections. The rotation of the two bearings drives the rotation of sections B and C, thereby deflecting the nozzle exit direction. In level flight mode, this nozzle is a typical Laval nozzle, capable of expelling airflow at supersonic speeds and maximizing nozzle thrust. In thrust vectoring mode, the nozzle can deflect the exit obliquely downwards, achieving deflection of the airflow exit direction.

Description

Technical Field

[0001] This invention relates to a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle and its design method, belonging to the field of thrust vectoring nozzle technology for aero-engines. Background Technology

[0002] In today's rapidly developing military technology, improving the maneuverability, agility, stealth, and short takeoff / vertical landing (STOVL) capabilities of high-performance fighter jets has become a focus of military research worldwide. STOVL aircraft, capable of taking off and landing over extremely short distances, have a wide range of applications in both military and civilian fields. Militarily, STOVL aircraft can be used for rapid deployment and evacuation, performing special missions, and operating in confined spaces, making them a vital strategic and tactical asset. In the civilian sector, STOVL aircraft can be used to connect remote or terrain-challenged areas, supporting missions such as medical evacuation, personnel transport, and supply delivery, providing reliable solutions.

[0003] Thrust vectoring nozzles are a key technology for short takeoff and landing (STOVL) aircraft, enabling them to adjust the thrust vector direction during takeoff and landing, facilitating takeoff and landing over extremely short distances. For example, the F-35B, a STOVL-capable aircraft, uses a three-bearing rotating vectoring nozzle. This nozzle can change its thrust vector by adjusting the nozzle direction, thus enabling STOVL. However, the three-bearing rotating vectoring nozzle suffers from complex structure, heavy weight, and slow response, hindering its further development and failing to meet the ever-increasing demands of high-performance fighter jets. This has led to the gradual phasing out of the three-bearing thrust vectoring nozzle technology. Therefore, researchers urgently need a reasonable, simple, and efficient design method to optimize the performance of thrust vectoring nozzles and make them more suitable for the requirements of future fighter jets. Summary of the Invention

[0004] To address the problems mentioned above, this invention provides a dual-bearing rotating vector nozzle structure and its design method based on a non-axisymmetric Laval nozzle. This nozzle simplifies the actuation structure of a three-bearing mechanical rotating nozzle, using only two bearings to achieve vector deflection, enabling more efficient and lightweight short takeoff and landing (STOVL) capabilities. Furthermore, by modifying the nozzle cross-section to an elliptical shape, the rotation of the nozzle bearings can occur within the expansion chamber. The two bearings are respectively arranged in the straight section and the expansion section. By combining the dual-bearing structure with the Laval nozzle, the aircraft can obtain greater thrust in level flight.

[0005] The technical method of the present invention is as follows: a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle, comprising: a straight section cylinder A, a first rotating section cylinder B, a second rotating section cylinder C, and a first bearing D disposed between the straight section cylinder A and the first rotating section cylinder B, and a second bearing E disposed between the first rotating section cylinder B and the second rotating section cylinder C. The deflection of the nozzle exit direction is achieved by rotating the first rotating section cylinder B and the second rotating section cylinder C.

[0006] Preferably, the front end of the straight section A of the nozzle is connected to the turbine outlet or the combustion chamber outlet of the engine, and its rear end is connected to the first bearing D. The cross-section of the straight section A of the nozzle is a circular cross-section with equal area.

[0007] Preferably, the first rotating section cylinder B rotates relative to the straight section cylinder A of the nozzle around the first bearing D. The first rotating section cylinder B includes a contraction section and a front half expansion section: the inner surface of the contraction section is a circular-to-elliptical surface, the inlet cross-section of the contraction section is the same as the cross-section along the nozzle straight section cylinder A, the outlet of the contraction section is the throat of the nozzle, and the outlet cross-section of the contraction section is an ellipse with a major-to-minor axis ratio of t = a / b, where a is the major axis of the ellipse and b is the minor axis of the ellipse; the flow channel cross-section of the contraction section smoothly transitions between a circular cross-section and an elliptical cross-section.

[0008] Preferably, the inner surface of the second rotating section cylinder C is an elliptical cone or platform with the rear half obliquely cut, and the cross-sectional shape of its flow channel is an ellipse with a major-to-minor axis ratio of t = a / b; the second rotating section cylinder C rotates relative to the first rotating section cylinder B around the second bearing E, and the angle between the cross-section of the second bearing E and the axis of the straight section cylinder A such as the nozzle is α, and the value of α is in the range of 15°≤α≤45°.

[0009] Preferably, when the nozzle is in level flight mode, the axes of the straight section A of the nozzle, the first rotating section B, and the second rotating section C are collinear, and the normal of the intersection plane between the rear end of the first rotating section B and the front end of the second rotating section C is located in the horizontal plane.

[0010] Preferably, when the nozzle is in the vector deflection mode, under the action of the rotation drive mechanism, the first rotating section cylinder B rotates around the first bearing D relative to the straight section cylinder A of the nozzle, and the second rotating section cylinder C deflects around the axis of the second bearing E relative to the first rotating section cylinder B; during the rotation, the vector deflection angle β of the nozzle gradually increases from 0 to the maximum.

[0011] Preferably, during the mode switching process, the first rotating section cylinder B rotates relative to the straight section cylinder A of the nozzle, and the second rotating section cylinder C rotates relative to the first rotating section cylinder B, with the direction of the first rotating section cylinder B relative to the straight section cylinder A of the nozzle being opposite to the direction of the second rotating section cylinder C relative to the first rotating section cylinder B; the mode switching process refers to the process of switching from the level flight mode of the nozzle to the vector deflection mode or from the vector deflection mode to the level flight mode.

[0012] Preferably, during the mode switching process, the angular velocity of the first rotating section cylinder B relative to the straight section cylinder A of the nozzle is half the angular velocity of the second rotating section cylinder C relative to the first rotating section cylinder B, so as to realize that the straight section cylinder A of the nozzle, the first rotating section cylinder B, and the second rotating section cylinder C all move in the vertical plane.

[0013] The design method for a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle is characterized by the following specific design steps:

[0014] Step S1: Determine the nozzle throat area A based on the overall engine requirements. th The nozzle exit area A e The overall expansion section length L of the nozzle and the required vector deflection angle β;

[0015] Step S2: Obtain the installation angle of the second bearing E, i.e., the included angle α, based on the vector deflection angle β;

[0016] Step S3: Solve for the ratio t of the major and minor axes of the elliptical cross section of the overall expansion segment;

[0017] Step S4: Based on the nozzle throat area A th Export area A e The ratio t of the major and minor axes of the elliptical cross section is used to calculate the lengths of the major and minor axes of the throat section and the nozzle exit section, thereby obtaining the nozzle cross-sectional shape;

[0018] Step S5: Design the surface profiles of the straight section cylinder A (such as the nozzle), the first rotating section cylinder B, and the second rotating section cylinder C. The contraction section of the first rotating section cylinder B is a circular-to-elliptical surface. Its inlet is smoothly connected to the outlet of the straight section cylinder A (such as the nozzle), and the outlet of the contraction section is smoothly connected to the first half of the expansion section.

[0019] Preferably, the design method of a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle is characterized in that, in step S2, the installation angle α of the second bearing E and the vector deflection angle β of the nozzle have the following relationship: α=90°-β / 2;

[0020] In step S3, the installation angle α of the second bearing E has the following relationship with the parameters of the elliptical cone:

[0021]

[0022] Among them, a e b is the length of the major axis of the ellipse at the nozzle exit section. e Let c be the length of the minor axis of the ellipse at the nozzle exit section, which is obtained based on the overall expansion section length L and the overall expansion section expansion ratio n. The expansion ratio n is the ratio of the nozzle exit area to the throat area.

[0023] In step S4, the calculation methods for the major and minor axes of the elliptical cross-section of the nozzle throat and the elliptical cross-section of the nozzle exit are as follows: Where a th b th These are the semi-major axis and semi-minor axis of the elliptical cross-section of the nozzle throat, respectively. e b e These are the semi-major axis and semi-minor axis of the elliptical cross section at the nozzle exit, respectively.

[0024] Beneficial effects:

[0025] This invention proposes a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle and its design method. This design method not only simplifies the nozzle structure and reduces weight, but also improves the deflection response speed through the dual-bearing system. Compared with traditional technologies, the advantages of this invention are mainly reflected in the following aspects:

[0026] First, this invention employs a Laval nozzle design, which, compared to traditional converging-out rotary vector nozzles, is expected to increase the nozzle's thrust in its design state, thereby enhancing the aircraft's maneuverability. Second, the vector deflection mechanism utilizes a dual-bearing system. By reducing the number of bearings and actuators, the weight of the entire deflection system is reduced, improving stability and thus contributing to the overall engine's reliability and lifespan. Finally, this invention also offers a simple and rational design method, enabling the design and calculation of dual-bearing rotary vector nozzles according to specific requirements, thus improving the feasibility of the proposed solution.

[0027] This invention overcomes some of the drawbacks of traditional thrust vectoring technology and features significant innovations in nozzle structure and design methods. By providing a more efficient and feasible thrust vectoring technology, it is expected to provide strong support for the development of future high-performance fighter jets. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the main structure of the present invention in level flight mode;

[0029] Figure 2 This is a schematic diagram of the structure of the present invention in the vector state;

[0030] Figure 3 This is a two-dimensional schematic diagram of the inner surface under the level flight mode of the present invention;

[0031] Figure 4 This is a two-dimensional schematic diagram of the inner surface in the vector state of the present invention;

[0032] Figure 5 This is a schematic diagram of the design process of the present invention;

[0033] Figure 6 This is a schematic diagram of the main geometric design parameters of the present invention;

[0034] Figure 7 This is a two-dimensional schematic diagram of the obliquely expanded section of the present invention; Detailed Implementation

[0035] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, specific details are set forth for illustrative purposes rather than limiting, to aid in a comprehensive understanding of the invention. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the invention. Those skilled in the art should understand that modifications or substitutions to the details and form of the technical solutions of the present invention can be made without departing from the scope of the invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0036] This invention provides a dual-bearing rotating vector nozzle structure and its design method based on a non-axisymmetric Laval nozzle. The nozzle structure includes: a straight section A of the nozzle, a first rotating section B, a second rotating section C, and bearings D and E connected to these three sections. Bearing D is connected to sections A and B, and bearing E is connected to sections B and C. The rotation of the bearings drives the rotation of the latter two sections of the nozzle to achieve the deflection of the nozzle exit direction.

[0037] Specifically, such as Figure 1 As shown, cylinder A is a straight section, its function is to connect the nozzle to the engine. The front end of cylinder A is connected to the engine turbine outlet or combustion chamber outlet, and the rear end is connected to bearing D. The friction section of the straight cylinder A is a circular cross-section with equal area.

[0038] Cylinder B can rotate relative to cylinder A around bearing D. Cylinder B includes a contraction section and a front expansion section. The inner surface of the contraction section of cylinder B is a circular-to-elliptical shape. The inlet of the contraction section is a circular cross-section with the same cross-section as the straight section. The outlet of the contraction section is the throat of the nozzle, and its cross-section is an ellipse with a major-to-minor axis ratio of t = a / b. The flow channel cross-sectional shape of the nozzle's contraction section smoothly transitions from a circular cross-section to an elliptical cross-section along the fluid flow direction.

[0039] The inner surface of cylinder C is an elliptical cone / table surface with the rear half obliquely cut. The cross-sectional shape of the flow channel of cylinder C is an ellipse with a major-to-minor axis ratio of t = a / b. Cylinder C can rotate relative to cylinder B around bearing E. The angle between the cross-section of bearing E and the axis of cylinder A is α, which is the installation angle of bearing E. The value of α ranges from 15° ≤ α ≤ 45°.

[0040] Preferably, when the nozzle body is in a level flight state, the axes of the three straight cylinders A, B, and C are collinear, and the normal line of the intersection plane between the rear end of cylinder B and the front end of cylinder C is located in the horizontal plane.

[0041] When the nozzle body is in a vector state, under the action of the rotary drive mechanism, the rotating cylinder B rotates relative to the straight section cylinder A around the bearing D, and the rotating cylinder C deflects about the axis of the rotating cylinder B around the bearing E, until the circular axis of the nozzle body's exit section is tilted downwards relative to the axis of the straight section cylinder. The angle between the two axes is the vector deflection angle β. The vector deflection angle β of the nozzle has the following relationship with the bearing E installation angle α: β = 180° - 2α

[0042] During the mode switching process, cylinder B rotates relative to cylinder A, cylinder C rotates relative to cylinder B, and the direction of cylinder B relative to cylinder A is opposite to the direction of cylinder C relative to cylinder B; the mode switching process refers to the process of the nozzle level flight mode to vector deflection mode or the vector deflection mode to level flight mode.

[0043] Furthermore, during the mode switching process, the angular velocity of cylinder B relative to cylinder A is half that of cylinder C relative to cylinder B, so that cylinder A, cylinder B and cylinder C all move in the vertical plane.

[0044] This invention also provides a design method for a dual-bearing rotating vector nozzle based on the above-mentioned non-axisymmetric Laval nozzle, the specific design steps of which include:

[0045] 1. Determine the nozzle throat area A based on the overall engine requirements. th Nozzle exit area A e The length L of the nozzle expansion section and the required vector deflection angle β.

[0046] 2. Obtain the bearing E installation angle α based on the vector deflection angle β.

[0047] 3. Solve for the ratio t of the major and minor axes of the expanded segment of the ellipse.

[0048] 4. Based on the nozzle throat area A th Export area A e The ratio t of the major and minor axes of the ellipse is used to calculate the major and minor axes of the throat section and the outlet section, thereby obtaining the cross-sectional shape.

[0049] 5. Design the profiles of cylinder A, cylinder B, and cylinder C.

[0050] Specifically, the bearing E installation angle α in step 2 is the angle between the plane where the bearing is located and the nozzle axis in level flight. Its relationship with the maximum vector deflection angle can be determined according to... Figure 6 We obtain α = 90° - β / 2

[0051] Specifically, the solution principle and calculation method in step 3 are as follows:

[0052] The entire expansion section of the nozzle can be viewed as an elliptical frustum with the apex of an elliptical cone removed. The cross-section of this frustum is entirely elliptical, and the ratio of its major and minor axes, t = a / b, is a constant. The equation of this elliptical cone is: Where a is the length of the major axis of the ellipse at the outlet section, b is the length of the minor axis of the ellipse at the outlet section, and c can be obtained from the length L of the expansion section and the expansion ratio n of the expansion section:

[0053]

[0054] Wherein, the expansion section length L is the axial distance from the throat to the exit in the nozzle's level flight state, and the expansion ratio n is the ratio of the nozzle exit area to the throat area.

[0055] After the expansion segment is obliquely cut by the cross section, to ensure that the cut is a standard circle, according to the condition that the plane and the elliptical cone intersect, the cross section must be perpendicular to the frontal plane and make an angle α with the horizontal plane. The relationship between angle α and the parameters of the elliptical cone is as follows: Furthermore, the ratio of the major and minor axes of the ellipse, t, can be obtained from this formula: t = a / b.

[0056] Specifically, in step 4, the major and minor axes of the throat and outlet ellipses can be calculated based on the areas of the two cross-sections and the ratio of their major and minor axes. For any ellipse, its area is equal to the product of pi (π) and its semi-major and semi-minor axes. The values ​​of the semi-major and semi-minor axes of the throat and outlet cross-sections can be obtained using the area calculation formula. The specific calculation formula is as follows:

[0057]

[0058]

[0059] Where a th b th , where a is the length of the semi-major axis and semi-minor axis of the elliptical cross section of the nozzle throat. e b e The semi-major axis and semi-minor axis lengths of the elliptical cross section at the nozzle exit are given.

[0060] Specifically, in step 5, the contraction section of cylinder B is a circular-to-elliptical surface. To ensure a uniform distribution of airflow velocity and pressure at the throat, the inlet of cylinder B should be smoothly connected to the outlet of cylinder A, and the outlet of the contraction section should be smoothly connected to the expansion section.

[0061] Specifically, in step 5, for the entire expansion section of the nozzle (including part of the inner surface of cylinder B and the inner surface of cylinder C), its cross-section is an ellipse with equal ratios of its major and minor axes, the ratio being t.

[0062] This invention also relates to a method for calculating the radius and center coordinates of the tangent circle formed by oblique cutting of the nozzle expansion section by the section containing bearing E. Specific calculation steps will be described later. Figure 7 A detailed explanation is provided. To prevent errors due to confusing parameter naming, we only provide a clear calculation method without including specific formulas, enabling users to accurately calculate the required parameter values ​​using this method.

[0063] Figure 7 This is a front view of the invention, showing only the expanded section. Figure 7 The x-axis of the coordinate system coincides with the nozzle axis in level flight, and the y-axis is parallel to the minor semi-axis of the ellipse. The oblique tangent interface is perpendicular to the frontal view plane and intersects the frontal section to form a straight line L with an angle of α. The specific calculation methods for the coordinates of the center point M and the radius of the tangent circle are as follows: First, based on the half-length b of the minor axis of the throat section ellipse calculated in step 4 above... th The semi-length b of the minor axis of the ellipse at the outlet section e The equations of lines L1 and L2 can be obtained. The equation of line L can be obtained based on the axial position and included angle α of the bearing. Then, based on the intersection of two lines in the plane, the intersection point P1 of line L and line L1, and the intersection point P2 of line L and line L2 can be found. The coordinates of the center point M of these two intersection points and the length of line segment P1P2 can be obtained. The length of line segment P1P2 is the diameter of the circle to be cut, and the center point M is the center of the circle to be cut, which is also the intersection point of the bearing E's axis of rotation and the oblique section.

Claims

1. A dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle, characterized in that, include: The nozzle consists of a straight section cylinder (A), a first rotating section cylinder (B), a second rotating section cylinder (C), a first bearing (D) located between the straight section cylinder (A) and the first rotating section cylinder (B), and a second bearing (E) located between the first rotating section cylinder (B) and the second rotating section cylinder (C). The rotation of the first rotating section cylinder (B) and the second rotating section cylinder (C) enables the nozzle outlet direction to be deflected. The first rotating section cylinder (B) rotates relative to the straight section cylinder (A) of the nozzle around the first bearing (D). The first rotating section cylinder (B) includes a contraction section and a front expansion section: the inner surface of the contraction section is a circular-to-elliptical shape, the inlet cross-section of the contraction section is the same as the cross-section along the nozzle straight section cylinder (A), and the outlet of the contraction section is the throat of the nozzle. The outlet cross-section of the contraction section is the ratio of its major axis to its minor axis. t=a / b An ellipse, in which a Let be the major axis of the ellipse. b The minor axis is the ellipse; the flow channel cross-section of the contraction section smoothly transitions between a circular cross-section and an elliptical cross-section.

2. The dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 1, characterized in that, The front end of the straight section of the nozzle (A) is connected to the turbine outlet or the combustion chamber outlet of the engine, and its rear end is connected to the first bearing (D). The cross-section of the straight section of the nozzle (A) is a circular cross-section with equal area.

3. The dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 1, characterized in that, The inner surface of the second rotating section cylinder (C) is an elliptical cone or platform with the rear half obliquely cut, and its flow channel cross-sectional shape is the ratio of its major axis to its minor axis. t=a / b The second rotating section cylinder (C) rotates relative to the first rotating section cylinder (B) around the second bearing (E), and the angle between the cross section of the second bearing (E) and the axis of the straight section cylinder (A) such as the nozzle is α, and the value of α is in the range of 15°≤α≤45°.

4. The dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 1, characterized in that, When the nozzle is in level flight mode, the axes of the straight section of the nozzle (A), the first rotating section of the nozzle (B), and the second rotating section of the nozzle (C) are collinear, and the normal of the intersection plane between the rear end of the first rotating section of the nozzle (B) and the front end of the second rotating section of the nozzle (C) is located in the horizontal plane.

5. The dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 3, characterized in that, When the nozzle is in the vector deflection mode, under the action of the rotation drive mechanism, the first rotating section cylinder (B) rotates around the first bearing (D) relative to the straight section cylinder (A) of the nozzle, and the second rotating section cylinder (C) deflects around the axis of the second bearing (E) relative to the first rotating section cylinder (B); during the rotation, the vector deflection angle β of the nozzle gradually increases from 0 to the maximum.

6. The dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 1, characterized in that, During the mode switching process, the first rotating section cylinder (B) rotates relative to the straight section cylinder (A) of the nozzle, and the second rotating section cylinder (C) rotates relative to the first rotating section cylinder (B). The direction of the first rotating section cylinder (B) relative to the straight section cylinder (A) of the nozzle is opposite to the direction of the second rotating section cylinder (C) relative to the first rotating section cylinder (B). The mode switching process refers to the process of switching from the level flight mode of the nozzle to the vector deflection mode or from the vector deflection mode to the level flight mode.

7. The dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 1, characterized in that, During the mode switching process, the angular velocity of the first rotating section cylinder (B) relative to the straight section cylinder (A) of the nozzle is half that of the second rotating section cylinder (C) relative to the first rotating section cylinder (B), so as to achieve that the straight section cylinder (A), the first rotating section cylinder (B), and the second rotating section cylinder (C) all move in the vertical plane.

8. The design method for a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 4, characterized in that, The specific design steps include: Step S1: Determine the nozzle throat area A based on the overall engine requirements. th The nozzle exit area A e The overall expansion section length L of the nozzle and the required vector deflection angle β; Step S2: Obtain the installation angle of the second bearing (E), i.e., the included angle α, based on the vector deflection angle β; Step S3: Solve for the major-minor axis ratio of the elliptical cross-section of the overall expansion segment. t ; Step S4: Based on the nozzle throat area A th Export area A e and the ratio of the major and minor axes of the elliptical cross section t Calculate the lengths of the major and minor axes of the throat section and the nozzle exit section to obtain the nozzle cross-sectional shape; Step S5: Design the profiles of the straight section cylinder (A), the first rotating section cylinder (B), and the second rotating section cylinder (C). The contraction section of the first rotating section cylinder (B) is a circular-to-elliptical profile. Its inlet is smoothly connected to the outlet of the straight section cylinder (A), and the outlet of the contraction section is smoothly connected to the first half of the expansion section.

9. The design method for a dual-bearing rotating vector nozzle based on a non-axisymmetric Laval nozzle according to claim 8, characterized in that, In step S2, the installation angle α of the second bearing (E) and the vector deflection angle β of the nozzle have the following relationship: ; In step S3, the installation angle α of the second bearing (E) has the following relationship with the parameters of the elliptical cone: ;in, a e The length of the major axis of the ellipse at the nozzle exit section. b e The length of the minor axis of the ellipse at the nozzle exit section. c Based on the overall expansion segment length L and the overall expansion ratio n get: expansion ratio n The ratio of nozzle exit area to throat area. ; In step S4, the calculation methods for the major and minor axes of the elliptical cross-section of the nozzle throat and the nozzle exit are as follows: , , ;in a th ，b th These are the semi-major axis and semi-minor axis of the elliptical cross-section of the nozzle throat, respectively. a e ，b e These are the semi-major axis and semi-minor axis of the elliptical cross section at the nozzle exit, respectively.

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