A design method for the outer adjustment plate of a convergent-divergent nozzle

Abstract

The present application belongs to the field of aero-engines, and in particular, is a design method for an outer adjustment plate of a convergent-divergent nozzle, comprising: establishing a guide line on a variable cross-section segment, determining a distance H1 from the guide line to the center axis of the engine; establishing a first variable cross-section segment at the front end of the outer adjustment plate based on a first endpoint P1 of the guide line, and establishing a second variable cross-section segment at the rear end of the outer adjustment plate based on a second endpoint P2 of the guide line; the radius R3 of the cross-section line at the front end of the variable cross-section segment, the angle β of the cross-section line at the front end of the variable cross-section segment, the length L3 of the cross-section line at the front end of the transition segment, and the radius R4 of the cross-section line at the front end of the overlap segment; the distance L5 between the two end points of the cross-section line at the rear end of the variable cross-section segment, the radius R5 of the cross-section line at the rear end of the overlap segment, the length L4 of the cross-section line at the rear end of the transition segment, and the distance L6 between the end point of the cross-section line at the rear end of the overlap segment and the second endpoint P2; establishing a turning line of the arc segment based on the guide line and the first endpoint P1; determining a radius parameter R6 of the turning line and a length L7 of the turning line along the guide line direction.

Description

Technical Field

[0001] The present application belongs to the field of aero-engines, and in particular relates to a design method for an external adjustment plate of a convergent-divergent nozzle. Background Art

[0002] With the development of aviation, how to improve the stealth performance of aircraft engines has become an important research field. The outer adjustment plate of the convergent-divergent nozzle is an important component to shield the high-temperature components inside the nozzle and improve the stealth performance of the engine. At present, the outer adjustment plates of the convergent-divergent nozzle assembly in China are mostly arc-shaped outer surfaces, and there are gaps between adjacent outer adjustment plates in the large nozzle state, which cannot achieve the shielding of internal components in all states, which undoubtedly affects the stealth performance of the engine. Based on this, a design method for a fully shielded wedge-shaped outer adjustment plate suitable for a convergent-divergent nozzle is proposed to standardize the design method and process of such outer adjustment plates, which can be applied to convergent-divergent nozzles of different structural sizes, and quickly and conveniently transform the solution into a product.

[0003] The external adjustment plates currently used for the expansion nozzle have the following disadvantages:

[0004] 1. The outer surface of the outer adjustment plate is arc-shaped, which affects the radar stealth effect;

[0005] 2. There is a gap between adjacent outer adjustment plates in the large nozzle state, which makes it impossible to shield the high-temperature components inside the nozzle in the full state, affecting the infrared stealth effect;

[0006] 3. There is no perfect design method for a fully shielded wedge-shaped external adjustment piece. Summary of the invention

[0007] In order to solve the above problems, the present application provides a design method for an outer adjustment piece of a convergent-divergent nozzle, wherein the profile of the outer adjustment piece includes four regions: a variable cross-section section, a transition section, an overlap section, and an arc section; wherein the front end is the end of the convergent-divergent nozzle close to the engine nozzle, and the rear end is the tail end of the convergent-divergent nozzle;

[0008] Step S1: Establish a guide line on the variable cross-section segment and determine the distance H from the guide line to the engine centerline 1 ; The guide line is as follows Figure 4 As shown, the two endpoints P 1 , P 2 It is the starting point and the end point of the variable cross-section segment. The above-mentioned variable cross-section segment, transition segment, overlap segment and arc segment are all formed by passing through the cross-section line they have and sweeping based on the guide line.

[0009] Step S2: Based on the first endpoint P of the guide line 1 Establish the first variable cross-section section at the front end of the outer adjustment piece, based on the second endpoint P of the guide line 2 Establishing a second variable cross-section section at the rear end of the outer adjustment plate;

[0010] Step S3: Determine the radius R of the front end cross-section line of the first variable cross-section segment 3 , the angle β of the front section line of the variable section segment, the length L of the front section line of the transition section 3 , the radius R of the front section line of the overlap section 4 ; Determine the distance L between the two end points of the rear section line of the second variable section segment 5 , the radius R of the rear section line of the overlap section 5 , the length of the cross-section line at the rear end of the transition section L 4 , the end point of the rear section line of the overlapped segment and the second end point P 2 The distance L 6 ;

[0011] The arc segment is formed by the first variable section segment rotating along the rotation line, the variable section segment, the transition segment, and the overlap segment are formed by the first variable section segment and the second variable section line sweeping along the guide line, and the first variable section segment and the second variable section line are both located on the normal plane of the nozzle center axis. Specifically,

[0012] The variable section segment is formed by sweeping the front section line of the variable section segment and the rear section line of the variable section segment along the guide line; wherein the front section line of the variable section segment is in an arc shape, and the rear section line of the variable section segment is two line segments with intersecting endpoints.

[0013] The transition section is formed by sweeping a front section line of the transition section and a rear section line of the transition section along a guide line; wherein the front section line of the transition section and the rear section line of the transition section are both straight lines;

[0014] The overlap section is formed by sweeping the front section line of the overlap section and the rear section line of the overlap section along the guide line; wherein the front section line of the overlap section and the rear section line of the overlap section are both arcs, and the centers of the circles are both on the nozzle axis;

[0015] Step S4: Based on the guide line and the first endpoint P 1 Establish the turning line of the arc segment;

[0016] Step S5: Determine the radius parameter R of the turning line 6 , the length of the turning line along the guide line direction L 7 .

[0017] Preferably, in step S1, the distance H between the guide line and the engine centerline is determined to be 1 The specific methods include:

[0018] Step 1: Obtain the distance H from the hinge point between the outer adjustment plate and the outlet area adjustment ring to the engine centerline 0 ; Get the turning radius R of the hinge point between the outer adjustment plate and the outlet area adjustment ring 1 ;

[0019] Step 2: Based on formula H 1 =H 0 +R 1 Determine the distance H from the guide line to the engine centerline 1 .

[0020] Preferably, the specific method of step S3 includes:

[0021] Step 1: Obtain the length L of the outer adjustment piece 1 , throat area, and outlet area are the smallest when the distance H from the end of the outer adjustment plate to the center axis of the engine 2 , throat area, and outlet area when the outer adjustment plate end is the largest and the distance from the engine centerline is H 3 ;

[0022] Step 2: Determine the radius R of the front end cross-section line of the first variable cross-section segment based on the following formula: 3 , the angle β of the front section line of the variable section segment, the length L of the front section line of the transition section 3 , the radius R of the front section line of the overlap section 4 ; Determine the distance L between the two end points of the rear section line of the second variable section segment 5 , the radius R of the rear section line of the overlap section 5 , the length of the cross-section line at the rear end of the transition section L 4 , the end point of the rear section line of the overlapped segment and the second end point P 2 The distance L 6 :

[0023] R 3 =H 1 , R 4 =H 1 -tc 1 ,

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030] t--Thickness of outer adjustment sheet;

[0031] n--Number of outer adjustment pieces in the circumferential direction;

[0032] γ--the shaping angle of the end of the outer adjustment piece;

[0033] θ 1 --The first preset angle parameter of the section line;

[0034] θ 2 --Second preset angle parameter of the section line;

[0035] c 1 --First preset size parameter;

[0036] c 2 --Second preset size parameter;

[0037] c 3 --Third preset size parameter;

[0038] c 4 --Fourth preset size parameter;

[0039] δ, K 1 is an algebraic expression.

[0040] Preferably, step S5 determines the radius parameter R of the turning line 6 , the length of the turning line along the guide line direction L 7 The specific formula is:

[0041]

[0042] L 7 =R 1 tanα.

[0043] Preferably, step S5 is followed by step S6:

[0044] Establish the 3D structural model of the outer adjustment piece assembly and correct θ 1 ,θ 2 、c 1 、c 3 、c 2 、c 4 .

[0045] Preferably, the modified θ 1 ,θ 2 、c 1 、c 3 、c 2 、c 4 The constraints are: when the throat area and outlet area of ​​the convergent-divergent nozzle are the smallest, the overlap section is blocked; when the throat area and outlet area of ​​the convergent-divergent nozzle are the largest, the overlap section is exposed.

[0046] Preferably, the modified θ 1 ,θ 2 、c 1 、c3 、c 2 、c 4 The goal is: the area of ​​the variable cross-section section reaches a first preset value, the area of ​​the transition section reaches a second preset value, and the area of ​​the overlap section reaches a third preset value.

[0047] Preferably, the first endpoint P 1 The midpoint of the cross-section line at the front end of the variable cross-section segment; the second endpoint P 2 The midpoint of the section line at the rear end of the variable section.

[0048] The advantages of this application include: standardizing the design method and process of such external adjustment plates, being applicable to convergent-expandable nozzles of different structural sizes, and quickly and conveniently converting the solution into a product. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the guide line (1-c) and the turning line (1-d);

[0050] Figure 2 Section line (1-a);

[0051] Figure 3 Section line (1-b);

[0052] Figure 4 Parametric design of the three-dimensional structure of the external adjustment piece;

[0053] Figure 5 Schematic diagram of the installation of the external adjustment piece;

[0054] Figure 6 Schematic diagram of the structure of the outer adjustment piece;

[0055] Figure 7 3D parametric simulation (A 8min , A 9min ) Schematic diagram;

[0056] Figure 8 3D parametric simulation (A 8max , A 9max ) Schematic diagram;

[0057] Fig. 9 Schematic diagram of the design of the external adjustment plate movement mechanism.

[0058] Among them: 1-1, variable cross-section section; 1-2, transition section; 1-3, overlap section; 1-4, arc section; 1-c, guide line; 1-a, first variable cross-section section; 1-b, second variable cross-section section; 1-d, turning line. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0060] The present application provides a design method for an outer adjustment piece of a convergent-divergent nozzle, wherein the profile of the outer adjustment piece 1 includes four regions: a variable cross-section section 1-1, a transition section 1-2, an overlap section 1-3, and an arc section 1-4;

[0061] Step S1: Establish a guide line 1-c on the variable cross-section segment 1-1 and determine the distance H from the guide line 1-c to the center axis of the engine 1 ;

[0062] Step S2: Based on the first endpoint P of the guide line 1-c 1 The first variable cross-section section 1-a at the front end of the outer adjustment piece 1 is established, based on the second end point P of the guide line 1-c. 2 Establish a second variable cross-section section 1-b at the rear end of the outer adjustment plate 1;

[0063] Step S3: Determine the radius R of the front end cross-section line of the first variable cross-section segment 1-1 3 , the angle β of the front section line of the variable section section 1-1, the length L of the front section line of the transition section 1-2 3 , Radius R of the front section line of the overlap section 1-3 4 ; Determine the distance L between the two end points of the rear end section line of the variable section segment 1-1 of the second variable section segment 1-b 5 , Radius R of the rear section line of the overlap section 1-3 5 , the length of the rear section line of transition section 1-2 L 4 , the end point of the rear end section line of the overlap section 1-3 and the second end point P 2 The distance L 6 ;

[0064] The arc segment 1-4 is formed by the first variable section segment 1-a rotating along the rotation line 1-d, the variable section segment 1-1, the transition segment 1-2, and the overlap segment 1-3 are formed by the first variable section segment 1-a and the second variable section line 1-b sweeping along the guide line 1-c, and the first variable section segment 1-a and the second variable section line 1-b are both located on the normal plane of the nozzle center axis. Specifically,

[0065] The variable cross-section segment 1-1 is formed by sweeping the front cross-section line of the variable cross-section segment 1-1 and the rear cross-section line of the variable cross-section segment 1-1 along the guide line 1-c; wherein, the front cross-section line of the variable cross-section segment 1-1 is in an arc shape, and the rear cross-section line of the variable cross-section segment 1-1 is two line segments with intersecting endpoints.

[0066] The transition section 1-2 is formed by sweeping the front section line of the transition section 1-2 and the rear section line of the transition section 1-2 along the guide line 1-c; wherein the front section line of the transition section 1-2 and the rear section line of the transition section 1-2 are both straight lines;

[0067] The overlapping section 1-3 is formed by sweeping the front section line of the overlapping section 1-3 and the rear section line of the overlapping section 1-3 along the guide line 1-c; wherein the front section line of the overlapping section 1-3 and the rear section line of the overlapping section 1-3 are both arcs, and the centers of the circles are both on the nozzle axis;

[0068] Step S4: Based on the guide line 1-c and the first endpoint P 1 Establishing the turning line 1-d of the arc segment 1-4;

[0069] Step S5: Determine the radius parameter R of the turning line 1-d 6 , the length L of the turning line 1-d along the guide line 1-c 7 .

[0070] Preferably, in step S1, the distance H between the guide line 1-c and the engine centerline is determined to be 1 The specific methods include:

[0071] Step 1: Obtain the distance H from the hinge point between the outer adjustment plate 1 and the outlet area adjustment ring 5 to the center axis of the engine 0 ; Get the radius of gyration R of the hinge point between the outer adjustment plate 1 and the outlet area adjustment ring 5 1 ;

[0072] Step 2: Based on formula H 1 =H 0 +R 1 Determine the distance H from the guide line 1-c to the engine centerline 1 .

[0073] Preferably, the specific method of step S3 includes:

[0074] Step 1: Obtain the length L of the outer adjustment piece 11 , throat area, and outlet area are the smallest when the distance H from the end of the outer adjustment plate 1 to the center axis of the engine 2 , throat area, and outlet area when the maximum distance H is from the end of the outer adjustment plate 1 to the engine centerline 3 ;

[0075] Step 2: Determine the radius R of the front end cross-section line of the first variable cross-section segment 1-1 based on the following formula: 3 , the angle β of the front section line of the variable section section 1-1, the length L of the front section line of the transition section 1-2 3 , Radius R of the front section line of the overlap section 1-3 4 ; Determine the distance L between the two end points of the rear end section line of the variable section segment 1-1 of the second variable section segment 1-b 5 , Radius R of the rear section line of the overlap section 1-3 5 , the length of the rear section line of transition section 1-2 L 4 , the end point of the rear end section line of the overlap section 1-3 and the second end point P 2 The distance L 6 :

[0076] R 3 =H 1 , R 4 =H 1 -tc 1 ,

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] t--thickness of outer adjustment sheet 1;

[0084] n--Number of outer adjustment pieces in the circumferential direction;

[0085] γ--the trimming angle of the end of the outer adjustment piece 1;

[0086] θ 1 --The first preset angle parameter of section line 1-a is used to determine the transition section

[0087] 1-2, θ 1 =0.035;

[0088] θ 2 --Second preset angle parameter of section line 1-a; used to determine the overlap section

[0089] 1-3, θ 2 =0.017;

[0090] c 1 --The first preset size parameter; c 1 =1;

[0091] c 2 --The second preset size parameter; c 2 =0;

[0092] c 3 --The third preset size parameter; c 3 =0;

[0093] c 4 --The fourth preset size parameter; c 4 =0.

[0094] Preferably, step S5 determines the radius parameter R of the turning line 1-d. 6 , the length L of the turning line 1-d along the guide line 1-c 7 The specific formula is:

[0095]

[0096] L 7 =R 1 tanα.

[0097] Preferably, step S5 is followed by step S6:

[0098] Establish the 3D structural model of the outer adjustment piece 1 assembly and correct θ 1 ,θ 2 、c 1 、c 3 、c 2 、c 4 .

[0099] Preferably, a simplified assembly model is established with at least three outer adjustment plates in the circumferential direction. When the throat area and the outlet area are the smallest, the overlap sections 1-3 are blocked, and θ can be fine-tuned. 1 ,θ 2 、c 1 、c 3 The value is selected to increase the area of ​​the variable cross-section section 1-1 and reduce the exposed area of ​​the transition section 1-2 to improve the external rectification effect and stealth performance. Figure 7 ; When the throat area and outlet area are the largest, the overlap sections 1-3 are exposed, and c can be fine-tuned2 、c 4 The value is selected to ensure that the overlap section 1-3 covers the area below the variable cross-section section 1-1 of the adjacent outer adjustment piece 1, so as to achieve full-state internal component shielding, see Figure 8 After the parameters are adjusted, there is no need to recalculate the parameters as in Section 1. The detailed design of the external adjustment plate structure can be completed based on the simulation results.

[0100] The advantages of this application include: standardizing the design method and process of such external adjustment plates, being applicable to convergent-expandable nozzles of different structural sizes, and quickly and conveniently converting the solution into a product.

[0101] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for designing an outer adjustment plate of a convergent-divergent nozzle, wherein the profile of the outer adjustment plate (1) comprises: The invention relates to four regions, namely, a variable cross-section section (1-1), a transition section (1-2), an overlap section (1-3), and an arc section (1-4); wherein the design method comprises: Step S1: establishing a guide line (1-c) on the variable cross-section segment (1-1), and determining a distance H1 from the guide line (1-c) to the center axis of the engine; Step S2: establishing a first variable cross-section segment (1-a) at the front end of the outer adjustment piece (1) based on the first endpoint P1 of the guide line (1-c), and establishing a second variable cross-section segment (1-b) at the rear end of the outer adjustment piece (1) based on the second endpoint P2 of the guide line (1-c); Step S3: Determine the radius R3 of the front end cross-sectional line of the variable cross-sectional section (1-1), the angle β of the front end cross-sectional line of the variable cross-sectional section (1-1), the length L3 of the front end cross-sectional line of the transition section (1-2), and the radius R4 of the front end cross-sectional line of the overlapping section (1-3) of the first variable cross-sectional section (1-a); determine the distance L5 between the two end points of the rear end cross-sectional line of the variable cross-sectional section (1-1), the radius R5 of the rear end cross-sectional line of the overlapping section (1-3), the length L4 of the rear end cross-sectional line of the transition section (1-2), and the distance L6 between the end point of the rear end cross-sectional line of the overlapping section (1-3) and the second end point P2 of the second variable cross-sectional section (1-b); Step S4: establishing a turning line (1-d) of the arc segment (1-4) based on the guide line (1-c) and the first endpoint P1; Step S5: Determine the radius parameter R6 of the turning line (1-d) and the length L7 of the turning line (1-d) along the direction of the guide line (1-c).

2. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 1, characterized in that: The specific method for determining the distance H1 from the guide line (1-c) to the center axis of the engine in step S1 includes: Step 1: Obtain the distance H0 from the hinge point of the outer adjustment plate (1) and the outlet area adjustment ring (5) to the center axis of the engine; obtain the turning radius R1 of the hinge point of the outer adjustment plate (1) and the outlet area adjustment ring (5); Step 2: Determine the distance H1 from the guide line (1-c) to the center axis of the engine based on the formula H1=H0+R1.

3. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 2, characterized in that: The specific method of step S3 includes: Step 1: Obtain the length L1 of the outer adjustment piece (1), the distance H2 from the end of the outer adjustment piece (1) to the center axis of the engine when the throat area and the outlet area are the smallest, and the distance H3 from the end of the outer adjustment piece (1) to the center axis of the engine when the throat area and the outlet area are the largest; Step 2: Based on the following formula, determine the radius R3 of the front end cross-section line of the variable cross-section section (1-1), the angle β of the front end cross-section line of the variable cross-section section (1-1), the length L3 of the front end cross-section line of the transition section (1-2), and the radius R4 of the front end cross-section line of the overlapping section (1-3) of the first variable cross-section section (1-a); determine the distance L5 between the two end points of the rear end cross-section line of the variable cross-section section (1-1), the radius R5 of the rear end cross-section line of the overlapping section (1-3), the length L4 of the rear end cross-section line of the transition section (1-2), and the radius R5 of the rear end cross-section line of the overlapping section (1-3). The distance L6 between the end point of the rear end cross-section line of the overlapping section (1-3) and the second end point P2: R3=H1、R4=H1-t-c1、 t--thickness of outer adjustment piece (1); n--Number of outer adjustment pieces in the circumferential direction; γ--the end trimming angle of the outer adjustment piece (1); θ1--the first preset angle parameter of the cross-section line (1-a); θ2--the second preset angle parameter of the cross-section line (1-a); c1 - the first preset size parameter; c2 - the second preset size parameter; c3 - the third preset size parameter; c4--The fourth preset size parameter.

4. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 3, characterized in that: Step S5 determines the radius parameter R6 of the turning line (1-d) and the length L7 of the turning line (1-d) along the guide line (1-c). The specific formula is: L7 = R1tanα.

5. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 4, characterized in that: Step S5 is followed by step S6: A three-dimensional structural model of the outer adjustment piece (1) is established, and θ1, θ2, c1, c3, c2, and c4 are corrected.

6. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 5, characterized in that: The constraints for modifying θ1, θ2, c1, c3, c2, and c4 are as follows: when the throat area and the outlet area of ​​the converging-diverging nozzle are the smallest, the overlapping section (1-3) is blocked; when the throat area and the outlet area of ​​the converging-diverging nozzle are the largest, the overlapping section (1-3) is exposed.

7. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 1, characterized in that: The objectives of correcting θ1, θ2, c1, c3, c2, and c4 are: the area of ​​the variable cross-section section (1-1) reaches a first preset value, the area of ​​the transition section (1-2) reaches a second preset value, and the area of ​​the overlap section (1-3) reaches a third preset value.

8. The design method of the outer adjustment plate of the convergent-divergent nozzle according to claim 1, characterized in that: The first endpoint P1 is at the midpoint of the front end cross-section line of the variable cross-section segment (1-1); the second endpoint P2 is at the midpoint of the rear end cross-section line of the variable cross-section segment (1-1).

Images