Method for wing tank area protection design based on non-inclusion rotor trajectory quantification

Abstract

The application discloses a wing fuel tank area protection design method based on non-inclusion rotor track quantization, relates to the technical field of wing protection design, and obtains an engine nacelle outer contour surface, a wing lower surface skin, a wing fuel tank wall surface, a wing rib plane, a target rotor stage position, a fragment characteristic size, a scattering angle range and a fuel drop direction under the same aircraft body coordinate system; the scattering path of the fragment is determined according to the target rotor stage position, the fragment characteristic size and the scattering angle, and when the scattering path of the fragment intersects with the engine nacelle outer contour surface, the wing lower surface skin and the wing fuel tank wall surface in sequence, it is determined that the scattering angle meets the geometric penetration condition; the protection scattering angle is determined based on the minimum distance between the fuel drop path and the engine nacelle outer contour surface; and the minimum dry tank boundary is formed according to the intersection position of the fuel tank wall surface corresponding to the boundary scattering angle, and the actual dry tank area is determined in combination with the wing rib plane.

Description

Technical Field

[0001] This invention relates to the field of wing protection design technology, specifically to a wing fuel tank area protection design method based on non-containment rotor trajectory quantization. Background Technology

[0002] With the development of wing-mounted engine aircraft and high-bypass turbofan engines, the risk of debris scattering after rotor non-containment failure has become a crucial factor in the protection design of the wing fuel tank area. Existing designs typically combine three-dimensional digital prototypes of the aircraft, rotor non-containment failure analysis data, and wing fuel tank structural data to assess the spatial relationship between rotor debris and the engine nacelle, lower wing skin, and wing fuel tank walls.

[0003] The determination of existing dry compartment areas relies heavily on fixed scatter angle intervals and empirical envelopes, making it difficult to accurately identify the actual dry compartment boundaries that need protection. Because the gap relationship between the outer edge sweep range of debris, the fuel drip path and the outer contour surface of the engine nacelle is not continuously correlated, the critical position between the scatter angle that needs protection and the scatter angle that does not need protection is difficult to determine. As a result, the actual dry compartment area usually needs to be conservatively expanded outward, which can easily lead to an increase in the effective volume loss of the fuel tank and insufficient repeatability of the protection design results. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a wing fuel tank area protection design method based on non-containment rotor trajectory quantization, which solves the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution, comprising the following steps: S1. Obtain the outer contour of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the rib plane, the target rotor stage position, the debris characteristic size, the scattering angle range, and the fuel dripping direction in the same aircraft body coordinate system. S2. Select the dispersion angle within the dispersion angle range, and determine the corresponding fragment dispersion path according to the target rotor stage position, fragment characteristic size and dispersion angle. When the fragment dispersion path intersects the outer contour surface of the engine nacelle, the lower surface skin of the wing and the wing fuel tank wall in sequence along its extension direction, the dispersion angle satisfies the geometric crossing condition. S3. Under the scattering angle that satisfies the geometric crossing conditions, the intersection of the corresponding debris scattering path and the lower surface skin of the wing is taken as the starting position of fuel dripping, and a fuel dripping path is formed along the fuel dripping direction; when the minimum distance between the fuel dripping path and the outer contour surface of the engine nacelle is not greater than the preset safety gap, the corresponding scattering angle is determined as the scattering angle that needs to be protected. S4. When one of two adjacent scattering angles belongs to the scattering angle that needs protection and the other does not, reduce the angle interval between the two adjacent scattering angles, and re-determine the fragment scattering path and the scattering angle that needs protection for the new scattering angle obtained after reducing the angle interval, until the angle interval is not greater than the preset angle accuracy, and take the scattering angle that still belongs to the scattering angle that needs protection as the boundary scattering angle. S5. The boundary control position of the minimum dry compartment boundary is the intersection of the debris scattering path corresponding to the boundary scattering angle and the wing fuel tank wall. The minimum dry compartment boundary is formed by the boundary control position and the intersection of the wing fuel tank wall corresponding to each debris scattering angle that needs to be protected. The actual dry compartment area that encompasses the minimum dry compartment boundary is determined according to the wing rib plane.

[0006] Preferably, in S1, the whole-aircraft reference coordinate system in the three-dimensional digital prototype of the aircraft is used as the aircraft body coordinate system. Under the same aircraft body coordinate system, the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the wing rib plane and the position of the target rotor stage are obtained. Obtain the fragment characteristic size and scattering angle range from the rotor non-containment failure analysis data corresponding to the target rotor stage position; The direction of fuel dripping is determined by the direction of gravity in the aircraft's coordinate system under the aircraft's predetermined attitude.

[0007] Preferably, in S2, the fragment feature size includes the maximum outer edge size of the fragment; The path that takes the target rotor level position in the same aircraft body coordinate system as the starting position, the scattering direction determined by the corresponding scattering angle as the extension direction, and the scattering range of the outer edge of the fragment as defined by the maximum outer edge size of the fragment is determined as the fragment scattering path.

[0008] Preferably, in S2, the extension direction is the dispersion direction determined by the corresponding dispersion angle and pointing towards the side of the wing fuel tank; Along the extension direction, the intersection position of the debris dispersion path and the nacelle boundary formed by the outer contour surface of the engine nacelle is obtained sequentially; The boundary between the debris dispersion path and the skin formed by the lower surface skin of the wing; The point where the debris dispersion path intersects with the fuel tank wall formed by the wing fuel tank wall; When the nacelle junction, skin junction, and fuel tank wall junction all exist and are arranged sequentially along the extension direction, the dispersion angle is determined to satisfy the geometric crossing condition.

[0009] Preferably, in S3, the skin junction is used as the starting point for fuel dripping; The direction of fuel dripping is the direction of gravity in the aircraft's body coordinate system under the aircraft's predetermined attitude. The fuel drip path is formed by extending from the starting position of the fuel drip along the direction of fuel drip.

[0010] Preferably, in S3, the minimum spatial distance between the path position on the fuel drip path and the contour position on the outer contour surface of the engine nacelle is obtained, and the minimum spatial distance is used as the minimum gap distance corresponding to the scattering angle. When the minimum gap distance is not greater than the preset safety gap, the scattering angle is determined as the scattering angle that needs to be protected. When the minimum gap distance is greater than the preset safety gap, the scattering angle is determined to be a scattering angle that does not need to be protected.

[0011] Preferably, in S4, the multiple scattering angles to be determined are arranged in order from back to front; Among two adjacent scattering angles to be judged, if one belongs to the scattering angle that needs protection and the other does not, the two adjacent scattering angles to be judged will be used as the two endpoints of the subsequent reduction of the angle interval.

[0012] Preferably, in S4, the two endpoints include the first endpoint scattering angle and the second endpoint scattering angle, the first endpoint scattering angle is a scattering angle that needs to be protected, and the second endpoint scattering angle is not a scattering angle that needs to be protected. Choose a scattering angle between the first endpoint scattering angle and the second endpoint scattering angle. The angle value of the selected scattering angle is equal to the average of the angle values ​​of the first endpoint scattering angle and the second endpoint scattering angle. When the new scattering angle is a scattering angle that needs to be protected, replace the new scattering angle with the first endpoint scattering angle, and keep the second endpoint scattering angle unchanged; When the new scattering angle is not among the scattering angles that need to be protected, replace the new scattering angle with the second endpoint scattering angle, and keep the first endpoint scattering angle unchanged; Select a new scattering angle between the replaced first endpoint scattering angle and the replaced second endpoint scattering angle, and continue to replace the endpoints in the manner that the first endpoint scattering angle is replaced when the new scattering angle is a scattering angle that needs protection, and the second endpoint scattering angle is replaced when the new scattering angle is not a scattering angle that needs protection, until the angle difference between the first endpoint scattering angle and the second endpoint scattering angle is not greater than the preset angle accuracy.

[0013] Preferably, in S5, when the angle difference between the first endpoint scattering angle and the second endpoint scattering angle is not greater than a preset angle accuracy, the first endpoint scattering angle is determined as the boundary scattering angle. Obtain the boundary position between the debris scattering path corresponding to the boundary scattering angle and the wing fuel tank wall, and use the obtained boundary position as the boundary control position of the minimum dry compartment boundary; Obtain the boundary position between the debris scattering path and the wing fuel tank wall corresponding to each required scattering angle within the scattering angle range, and summarize the obtained boundary positions into a set of wing fuel tank wall boundary positions; An envelope is formed on the wing fuel tank wall. The boundary of the envelope is the control position of the envelope and the intersection position of the wing fuel tank wall. The envelope is the minimum dry compartment boundary.

[0014] Preferably, in S5, the adjacent rib plane that can encompass the minimum dry cabin boundary is selected based on the rib plane. The area between adjacent rib planes is the actual dry cabin area.

[0015] This invention provides a wing fuel tank area protection design method based on non-containment rotor trajectory quantization. It has the following beneficial effects: (1) By determining the debris scattering path based on the target rotor stage position, scattering angle and the maximum outer edge size of the debris, the penetration boundary position on the wing fuel tank wall can be determined according to the outer edge sweep range of the debris, thus solving the problem of inaccurate initial basis of the dry compartment boundary in the prior art.

[0016] (2) By forming a fuel drip path at the skin junction and obtaining the minimum gap distance between the fuel drip path and the outer contour surface of the engine nacelle, the penetration junction can be further transformed into the scattering angle that needs to be protected, thus solving the problem in the prior art that it is difficult to determine which penetration locations actually need to be included in the dry compartment boundary. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram illustrating the determination of the actual dry compartment area based on the rib plane according to the present invention. Figure 3 This is a schematic diagram of the debris outer edge sweep range and debris scattering path of the present invention; Figure 4 This is a schematic diagram showing the fuel drip path and minimum gap distance. Figure 5 This is a schematic diagram illustrating the geometric crossing condition determination of the present invention; Figure 5 (a) in the figure is a schematic diagram of the present invention satisfying the penetration condition; Figure 5 (b) in the figure is a schematic diagram of the present invention where the crossing condition is not met. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1 Please see Figures 1-5 This invention provides a wing fuel tank area protection design method based on non-containment rotor trajectory quantization. To achieve the above objectives, this invention is implemented through the following technical solution, including the following steps: S1. Obtain the outer contour of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the rib plane, the target rotor stage position, the debris characteristic size, the scattering angle range, and the fuel dripping direction in the same aircraft body coordinate system. S2. Select the dispersion angle within the dispersion angle range, and determine the corresponding fragment dispersion path according to the target rotor stage position, fragment characteristic size and dispersion angle. When the fragment dispersion path intersects the outer contour surface of the engine nacelle, the lower surface skin of the wing and the wing fuel tank wall in sequence along its extension direction, the dispersion angle satisfies the geometric crossing condition. S3. Under the scattering angle that satisfies the geometric crossing conditions, the intersection of the corresponding debris scattering path and the lower surface skin of the wing is taken as the starting position of fuel dripping, and a fuel dripping path is formed along the fuel dripping direction; when the minimum distance between the fuel dripping path and the outer contour surface of the engine nacelle is not greater than the preset safety gap, the corresponding scattering angle is determined as the scattering angle that needs to be protected. S4. When one of two adjacent scattering angles belongs to the scattering angle that needs protection and the other does not, reduce the angle interval between the two adjacent scattering angles, and re-determine the fragment scattering path and the scattering angle that needs protection for the new scattering angle obtained after reducing the angle interval, until the angle interval is not greater than the preset angle accuracy, and take the scattering angle that still belongs to the scattering angle that needs protection as the boundary scattering angle. S5. The boundary control position of the minimum dry compartment boundary is the intersection of the debris scattering path corresponding to the boundary scattering angle and the wing fuel tank wall. The minimum dry compartment boundary is formed by the boundary control position and the intersection of the wing fuel tank wall corresponding to each debris scattering angle that needs to be protected. The actual dry compartment area that encompasses the minimum dry compartment boundary is determined according to the wing rib plane.

[0020] In this embodiment, it is applied to the design stage of the dry compartment area of ​​the wing fuel tank of an aircraft with a wing-mounted engine. It is used to determine the minimum dry compartment boundary based on the scattering path of non-contained rotor debris and the risk of fuel dripping, and to determine the actual dry compartment area based on the wing rib plane.

[0021] Before implementation, the whole-aircraft reference coordinate system in the three-dimensional digital prototype of the aircraft is used as the aircraft body coordinate system. Under the aircraft body coordinate system, a unified spatial reference is established between the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the wing rib plane and the target rotor stage, so that subsequent intersection judgment, distance judgment and dry compartment boundary determination are all carried out under the same coordinate system.

[0022] In this embodiment, the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall and the rib plane are obtained from the three-dimensional digital prototype of the aircraft. The target rotor stage position, fragment characteristic size and scattering angle range are obtained from the rotor non-containment failure analysis data. The fuel dripping direction is determined according to the direction of gravity in the aircraft body coordinate system under the predetermined attitude of the aircraft.

[0023] In a specific engineering example of this embodiment, the target rotor stage position is X=12.40m, Y=4.82m, Z=-0.96m, the fragment characteristic size is the maximum outer edge size of the fragment, which is 0.462m, the scattering angle range is 5° backward to 5° forward, the preset safety clearance is 254mm, and the preset angle accuracy is 0.05°. The preset safety clearance is the model safety clearance verification input value, which is taken from the determined verification value in the airworthiness design requirements, model safety interval specifications, and engineering safety margin. The above values ​​are used to illustrate the method implementation process and are not used to limit the protection scope of the present invention.

[0024] In determining the debris scattering path, a scattering angle is selected within the scattering angle range, and the corresponding debris scattering path is determined based on the target rotor stage position, debris characteristic size, and the selected scattering angle. The debris scattering path is the geometric path formed by the movement of the maximum outer edge of the debris along the corresponding scattering direction.

[0025] For any dispersion angle, the debris dispersion path is obtained sequentially along the extension direction of the debris dispersion path, including the nacelle boundary formed by the outer contour surface of the engine nacelle, the skin boundary formed by the lower surface skin of the wing, and the fuel tank boundary formed by the wing fuel tank wall.

[0026] When the debris dispersion path does not form the boundary between the fuel tank wall and the wing fuel tank wall, the dispersion angle is not included in the fuel drip path judgment, and the dispersion angle is not used as a basis for the composition of the minimum dry compartment boundary.

[0027] The geometric crossing condition in this embodiment is a condition used in the design phase to screen the potential geometric arrival locations of the wing fuel tank. It indicates that the debris scattering path geometrically arrives at the outer contour surface of the engine nacelle, the lower surface skin of the wing, and the wall of the wing fuel tank in sequence, and is not used to directly characterize the material failure result.

[0028] When further material failure verification is required after geometric crossing screening, the material failure verification result is used as an additional screening result for the formation process of the minimum dry compartment boundary at the junction of the fuel tank wall.

[0029] After the divergence angle satisfies the geometric crossing condition, the skin boundary position corresponding to the divergence angle is taken as the starting position of fuel dripping, and a fuel dripping path is generated from the starting position of fuel dripping along the fuel dripping direction, so that the process of fuel leaking from the lower surface skin of the wing and approaching the engine nacelle can be expressed as a definite geometric path.

[0030] During the gap determination process, the minimum spatial distance between the path position on the fuel drip path and the contour position on the outer contour surface of the engine nacelle is obtained, and the minimum spatial distance is taken as the minimum gap distance corresponding to the scattering angle.

[0031] When the minimum gap distance is not greater than the preset safety gap, the scattering angle is determined as the scattering angle that needs to be protected. When the minimum gap distance is greater than the preset safety gap, the scattering angle is not considered as the scattering angle that needs to be protected.

[0032] In the initial judgment stage, the scattering angles are arranged in order from back to front, and the initial angle interval is 0.5°. In this embodiment, the minimum gap distances corresponding to 5.0°, 4.5°, 4.0° and 3.5° back are 181.7mm, 199.2mm, 216.4mm and 237.8mm respectively, and therefore all belong to the scattering angles that need to be protected.

[0033] In the same initial judgment stage, the minimum gap distance corresponding to 3.0° backward is 260.5mm. Therefore, 3.0° backward is not a scattering angle that needs to be protected. Thus, 3.5° backward and 3.0° backward are determined to be a set of adjacent scattering angles with a change in state, and the two are used as the two endpoints for subsequent reduction of the angle interval.

[0034] Between 3.5° and 3.0°, a rearward angle of 3.25° was selected, which is the average of the angle values ​​of the two endpoints. The minimum clearance distance corresponding to 3.25° is 247.1mm. Therefore, the original required protection endpoint scattering angle was replaced by 3.25°.

[0035] Continuing to select 3.125° backward between 3.25° and 3.0° backward, the minimum clearance distance corresponding to 3.125° backward is 252.6mm. Therefore, the original required protection end point scattering angle is replaced by 3.125° backward.

[0036] Continuing to select 3.0625° backward between 3.125° and 3.0° backward, the minimum clearance distance corresponding to 3.0625° backward is 256.8mm. Therefore, the original non-protected end scattering angle is replaced by 3.0625° backward.

[0037] Continuing to select 3.09375° backward between 3.125° and 3.0625° backward, the minimum gap distance corresponding to 3.09375° backward is 254.7mm. Therefore, the original non-protected end point scatter angle is replaced by backward 3.09375°. At this time, the angle difference between backward 3.125° and backward 3.09375° is 0.03125°, which is less than the preset angle accuracy of 0.05°. Therefore, backward 3.125°, which still belongs to the scatter angle that needs protection, is taken as the boundary scatter angle.

[0038] After determining the boundary scattering angle, the intersection position between the debris scattering path corresponding to the boundary scattering angle and the wing fuel tank wall is obtained, and the intersection position is used as the boundary control position; at the same time, the intersection position between the debris scattering path corresponding to each scattering angle that needs to be protected within the scattering angle range and the wing fuel tank wall is obtained, and the above intersection position is used as the wing fuel tank wall intersection position used to form the minimum dry compartment boundary.

[0039] When forming the minimum dry compartment boundary, the boundary control position and the intersection position of each wing fuel tank wall are mapped into the parameter domain of the wing fuel tank wall. The mapped positions are sorted according to the wingspan direction coordinates. Curved connecting segments are generated along the wing fuel tank wall between adjacent sorted positions. The curved connecting segments located on the outer side of the dry compartment and encompassing all intersection positions are combined to form an envelope. The envelope is then returned to the wing fuel tank wall as the minimum dry compartment boundary.

[0040] In this embodiment, the boundary control position and the set of the intersection of the wing fuel tank wall are both located on the wing fuel tank wall. After projecting the boundary control position and the set of the intersection of the wing fuel tank wall onto the parameter domain of the wing fuel tank wall, they are sorted in ascending order of wing spanwise coordinates. Continuous connecting lines are generated between adjacent positions along the parameter domain of the wing fuel tank wall after the sorting. The continuous connecting lines return to the wing fuel tank wall to form an envelope.

[0041] When there are local depressions between adjacent positions that prevent the continuous connecting line from encompassing the entire boundary of the wing fuel tank wall, the position of the continuous connecting line is adjusted along the outer direction of the wing fuel tank wall until the set of boundary control positions and the boundary positions of the wing fuel tank wall are both located on the side of the continuous connecting line facing the area to be protected, thus obtaining the minimum dry compartment boundary.

[0042] The actual dry compartment area is defined by the adjacent rib planes that can encompass the minimum dry compartment boundary, the wing fuel tank wall, and the fuel-free separation boundary set along the minimum dry compartment boundary. The adjacent rib planes are used to define the spanwise range of the actual dry compartment area, the minimum dry compartment boundary is used to define the local protection range of the actual dry compartment area on the wing fuel tank wall, and the fuel-free separation boundary is used to separate the actual dry compartment area from the fuel storage area.

[0043] When calculating the actual dry compartment volume, the spanwise integration range is first determined based on the adjacent rib planes. Then, the unfueled section area within each spanwise section is determined based on the minimum dry compartment boundary and the wing fuel tank wall. Subsequently, the volume of the unfueled section area is integrated along the spanwise integration range to obtain the actual dry compartment volume.

[0044] The actual dry compartment volume obtained by the fixed angle enumeration superposition method and the actual dry compartment volume obtained in this embodiment are both calculated under the same three-dimensional digital prototype of the aircraft, the same wing fuel tank wall, the same wing rib plane, the same preset safety clearance, and the same volume integration rule, so that the volume difference is caused by the change in the position of the minimum dry compartment boundary.

[0045] The minimum dry compartment boundary is used to represent the minimum protective boundary that needs to be drawn into the fuel tank wall of the wing, under the premise of meeting the risk of debris reaching the fuel tank wall and the safety clearance constraint of fuel dripping. The adjacent rib planes that can completely contain the minimum dry compartment boundary are determined according to the rib plane, and the interrib area between the adjacent rib planes is determined as the actual dry compartment area.

[0046] In this embodiment, the minimum dry compartment boundary is located in the inter-rib area defined by the 7th rib plane and the 8th rib plane, and the inter-rib area can completely contain the minimum dry compartment boundary. Therefore, the fuel tank space between the 7th rib plane and the 8th rib plane, and jointly defined by the minimum dry compartment boundary and the wing fuel tank wall structure boundary, is determined as the actual dry compartment area.

[0047] After the actual dry cabin area is determined, the actual dry cabin area is marked as a no-fuel area in the three-dimensional digital prototype of the aircraft, the fuel tank space outside the actual dry cabin area is reserved as a fuel storage area, and the boundary between the no-fuel area and the fuel storage area is output as the protection design result of the wing fuel tank area.

[0048] This embodiment can still be implemented under different application boundaries. When two adjacent scattering angles are both scattering angles that need to be protected, the next adjacent scattering angle is searched in the order from back to front, and it is determined whether there is a state change where one is a scattering angle that needs to be protected and the other is not.

[0049] When neither of the two adjacent scattering angles is a scattering angle that needs protection, continue to search for subsequent adjacent scattering angles in the order from back to front, and take the set of adjacent scattering angles that show a change in the state that needs protection as the two endpoints to reduce the angle interval.

[0050] When none of the scattered angles within the scattered angle range belong to the scattered angles that need to be protected, it means that under the current preset safety clearance and the aircraft's predetermined attitude, the non-contained rotor fragments do not pose a risk of fuel dripping that requires additional dry compartment isolation after reaching the wing fuel tank wall. In this case, the output will be a protection design result that does not add any actual dry compartment area.

[0051] When all the scattered angles within the scattered angle range belong to the scattered angles that need protection, the two endpoints of the scattered angle range are taken as the boundary scattered angles, and the junction of the wing fuel tank wall corresponding to the two endpoints is taken as the boundary control position, thus forming the minimum dry compartment boundary covering all the junction positions that need protection.

[0052] When the minimum dry cabin boundary spans more than two inter-rib regions, a continuous inter-rib region that can completely encompass the minimum dry cabin boundary is selected as the actual dry cabin region, so that the output results can correspond to the actual wing fuel tank structure layout.

[0053] When the minimum dry cabin boundary is close to a certain rib plane, the actual dry cabin area is determined based on whether the minimum dry cabin boundary is completely contained by the rib plane and its adjacent rib planes, so that the boundary control position will not cause the dry cabin area to be missed due to its proximity to the structural boundary.

[0054] To illustrate the technical effects of this embodiment, this embodiment is compared with the fixed angle enumeration and superposition method under the same three-dimensional digital prototype of the aircraft, the same preset safety clearance, and the same wing rib planar arrangement.

[0055] The fixed 1° enumeration and superposition method uses 4.0° backward as the outermost scatter angle to be protected. The actual dry tank area volume calculated according to the same fuel tank 3D mesh and the same structural boundary is 0.94m³. The fixed 0.5° enumeration and superposition method uses 3.5° backward as the outermost scatter angle to be protected. The actual dry tank area volume calculated according to the same fuel tank 3D mesh and the same structural boundary is 0.87m³. When using the angle interval reduction processing in this embodiment, 3.125° backward is determined as the boundary scatter angle. The actual dry tank area volume calculated according to the same fuel tank 3D mesh and the same structural boundary is 0.81m³.

[0056] Example 2 Please refer to Figure 1 Specifically: In S1, the whole-aircraft reference coordinate system in the three-dimensional digital prototype of the aircraft is used as the aircraft body coordinate system. Under the same aircraft body coordinate system, the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the wing rib plane and the position of the target rotor stage are obtained. Obtain the fragment characteristic size and scattering angle range from the rotor non-containment failure analysis data corresponding to the target rotor stage position; The direction of fuel dripping is determined by the direction of gravity in the aircraft's coordinate system under the aircraft's predetermined attitude.

[0057] In this embodiment, the reference coordinate system of the entire aircraft in the three-dimensional digital prototype is first read, and the reference coordinate system of the entire aircraft is determined as the aircraft body coordinate system. The origin of the aircraft body coordinate system is the reference point of the entire aircraft in the overall layout of the aircraft. The X-axis is forward along the longitudinal direction of the fuselage, the Y-axis is along the span of the right wing, and the Z-axis is upward along the height direction of the aircraft. The engine nacelle, wing, wing fuel tank, wing rib and engine all have assembly coordinate transformation relationship relative to the aircraft body coordinate system.

[0058] For a geometric object in the local coordinate system of a component, first read the translation and attitude angle of the local coordinate system of the component relative to the aircraft body coordinate system. The translation is used to determine the position of the origin of the local coordinate system of the component in the aircraft body coordinate system, and the attitude angle is used to determine the rotation relationship of the coordinate axes of the local coordinate system of the component relative to the coordinate axes of the aircraft body coordinate system.

[0059] When obtaining the outer contour surface of the engine nacelle, the discrete points of the outer surface of the engine nacelle in the local coordinate system are read. Then, based on the translation and attitude angle of the local coordinate system of the nacelle relative to the aircraft body coordinate system, the discrete points of the outer surface are expressed point by point in the aircraft body coordinate system, while maintaining the surface topological relationship between the discrete points of the outer surface, thus obtaining the outer contour surface of the engine nacelle in the aircraft body coordinate system.

[0060] When acquiring the lower surface skin of the wing, the discrete points of the skin surface located on the underside of the wing and covering the projected area of ​​the wing fuel tank are read from the 3D data of the wing. According to the translation amount and attitude angle of the wing local coordinate system relative to the aircraft body coordinate system, the discrete points of the skin surface are expressed in the aircraft body coordinate system. The lower surface skin of the wing is formed by maintaining the original surface topology relationship of the expressed discrete points of the skin surface.

[0061] When acquiring the wing fuel tank wall, the discrete points of the wall that enclose the fuel storage space in the boundary data of the wing fuel tank are read. According to the translation and attitude angle of the local coordinate system of the wing fuel tank relative to the aircraft body coordinate system, the discrete points of the wall are expressed in the aircraft body coordinate system. The wing fuel tank wall is formed by the expressed discrete points of the wall. The wing fuel tank wall is used to bear the boundary position between the subsequent debris dispersion path and the fuel tank.

[0062] When obtaining the rib plane, the plane control points of the rib web area are read, and the plane control points are expressed in the aircraft body coordinate system according to the assembly coordinate relationship of the rib. The corresponding rib plane is determined by the expressed plane control points. Multiple rib planes are arranged along the wing span and are used to solidify the minimum dry cabin boundary into the actual dry cabin area.

[0063] When obtaining the target rotor stage position, first read the position of the target rotor stage center point in the engine local coordinate system, then read the translation amount and attitude angle of the engine local coordinate system relative to the aircraft body coordinate system, express the target rotor stage center point in the aircraft body coordinate system based on the translation amount and attitude angle, and take the expressed center point position as the target rotor stage position.

[0064] In one specific embodiment, the translation of the engine local coordinate system relative to the aircraft body coordinate system is 12.18m in the X direction, 4.76m in the Y direction, and -1.04m in the Z direction. The engine local coordinate system has a 2.0° installation deflection angle about the Z-axis relative to the aircraft body coordinate system. The position of the target rotor stage center point in the engine local coordinate system is 0.22m in the X direction, 0.05m in the Y direction, and 0.08m in the Z direction. After applying the translation and installation deflection angle to the target rotor stage center point, the position of the target rotor stage in the aircraft body coordinate system is X=12.40m, Y=4.82m, and Z=-0.96m.

[0065] The fragment characteristic size and scattering angle range are obtained from the rotor non-containment failure analysis data corresponding to the target rotor stage position. The rotor non-containment failure analysis data includes the target rotor stage number, fragment size parameters, and scattering angle parameters. The fragment size parameters are used to determine the fragment characteristic size, and the scattering angle parameters are used to determine the scattering angle range.

[0066] In this embodiment, the target rotor stage number corresponds to a certain stage disk of the engine's high-pressure rotor. The maximum outer edge size of the fragment recorded in the fragment size parameter is 0.462m. Therefore, 0.462m is taken as the characteristic size of the fragment. The rearward limit angle and the forward limit angle recorded in the scattering angle parameter are 5° rearward and 5° forward, respectively. Therefore, the scattering angle range is defined as 5° rearward to 5° forward.

[0067] The direction of fuel dripping is determined based on the direction of gravity under the predetermined attitude of the aircraft. In this embodiment, the pitch angle and roll angle in the predetermined attitude of the aircraft are read first, and then the direction component of the direction of gravity relative to the aircraft body coordinate system is determined based on the pitch angle and roll angle, and the direction component is used as the direction of fuel dripping.

[0068] In one specific implementation, the aircraft is set to a safe clearance check attitude with a pitch angle of 5.0° and a roll angle of 0°. Under this attitude, the direction of gravity in the aircraft body coordinate system is represented by a direction vector pointing downwards from the wing and slightly deviating towards the tail. The subsequent fuel drip path extends along this direction vector.

[0069] This method is preferentially applied to static safety clearance verification attitudes and quasi-static safety clearance verification attitudes. Under the above verification attitudes, the fuel dripping direction is the direction vector of the gravity direction in the aircraft body coordinate system.

[0070] When the model design input includes flight speed, local flow field analysis results and nacelle induced flow correction parameters, the airflow correction direction is expressed in the aircraft body coordinate system, and the gravity direction and the airflow correction direction are combined into an equivalent dripping direction vector. The subsequent fuel dripping path extends along the equivalent dripping direction vector.

[0071] It should be noted that: the predetermined attitude of the aircraft corresponds to the predetermined safety clearance verification condition, and the fuel dripping direction is the equivalent dripping direction of the fuel after it leaks from the lower surface of the wing skin relative to the aircraft body coordinate system under the predetermined safety clearance verification condition. The equivalent dripping direction is used to characterize the main motion trend of the fuel after it leaks and approaches the outer contour surface of the engine nacelle.

[0072] When the predetermined safety clearance verification conditions are static verification conditions and quasi-static verification conditions, the equivalent dripping direction is determined by the direction vector of the gravity direction under the predetermined attitude of the aircraft in the aircraft body coordinate system, and the direction vector is used as the fuel dripping direction.

[0073] When the predetermined safety clearance verification condition includes the influence of flight speed, the equivalent droplet direction is obtained by normalizing the combination of the gravity direction vector, the incoming flow direction correction vector, and the local induced flow correction vector near the outer contour surface of the engine nacelle. The incoming flow direction correction vector is determined based on the predetermined speed of the aircraft and the incoming flow direction in the aircraft body coordinate system, and the local induced flow correction vector near the outer contour surface of the engine nacelle is determined based on the flow field verification data near the outer contour surface of the engine nacelle.

[0074] Before generating the fuel drip path, the equivalent drip direction is transformed to the same aircraft body coordinate system as the outer contour surface of the engine nacelle, the lower surface skin of the wing, and the wing fuel tank wall, so that the minimum clearance distance between the fuel drip path and the outer contour surface of the engine nacelle can be obtained under the same spatial reference.

[0075] The preset safety clearance is the minimum space interval that can be maintained between the fuel dripping path and the outer contour surface of the engine nacelle under the predetermined safety clearance verification condition. The preset safety clearance is determined jointly based on the model safety clearance verification requirements, the heat source boundary of the engine nacelle, the oil access limit, manufacturing and assembly deviations, and the discrete error of the digital prototype, and serves as the threshold for determining whether the scattering angle in S3 belongs to the scattering angle that needs to be protected.

[0076] After acquiring the above data, a consistency check is performed on the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the wing rib plane, the position of the target rotor stage, and the direction of fuel dripping. The consistency check includes length unit check, coordinate axis direction check, and assembly relative position check.

[0077] The length unit check confirms that the engine nacelle outer contour surface, wing lower surface skin, wing fuel tank wall, rib plane, and target rotor stage position all use meters as the length unit. The coordinate axis direction check confirms that all geometric objects use the same X-axis, Y-axis, and Z-axis directions. The assembly relative position check confirms that the engine nacelle outer contour surface is located outside the target rotor stage position, the wing lower surface skin is located outside the wing fuel tank wall, and the rib plane is arranged along the wing span.

[0078] In one data inspection result, the minimum spatial distance between the outer contour surface of the engine nacelle and the target rotor stage position is 0.68m, the minimum spatial distance between the lower surface skin of the wing and the target rotor stage position is 1.91m, the local thickness direction distance between the wing fuel tank wall and the lower surface skin of the wing is 0.16m to 0.28m, and the plane spacing between adjacent ribs is 0.52m, 0.56m and 0.61m, respectively. The above results indicate that the relative position of the input data in the aircraft body coordinate system conforms to the structural layout relationship of the wing-mounted engine aircraft.

[0079] After completing the consistency check, an input dataset is generated for subsequent steps. The input dataset includes the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the rib plane, the target rotor stage position, the debris feature size, the scattering angle range, and the fuel dripping direction. Among them, the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the rib plane, the target rotor stage position, and the fuel dripping direction are all expressed in the aircraft body coordinate system, and the debris feature size and scattering angle range are correlated with the target rotor stage position.

[0080] Example 3 Please refer to Figure 1 Specifically: In S2, the fragment feature size includes the maximum outer edge size of the fragment; The path that takes the target rotor level position in the same aircraft body coordinate system as the starting position, the scattering direction determined by the corresponding scattering angle as the extension direction, and the scattering range of the outer edge of the fragment as defined by the maximum outer edge size of the fragment is determined as the fragment scattering path.

[0081] In S2, the extension direction is the dispersion direction determined by the corresponding dispersion angle and pointing towards the side of the wing fuel tank; Along the extension direction, the intersection position of the debris dispersion path and the nacelle boundary formed by the outer contour surface of the engine nacelle is obtained sequentially; The boundary between the debris dispersion path and the skin formed by the lower surface skin of the wing; The boundary between the debris dispersion path and the fuel tank wall formed by the wing fuel tank wall.

[0082] In this embodiment, the fragment feature size is the maximum outer edge size of the fragment. The maximum outer edge size of the fragment is used to limit the outer edge sweep range formed by the fragment relative to the scattering direction during the scattering process. The fragment scattering path is based on the boundary that the outer edge of the fragment can reach as the geometric crossing judgment basis, so as to reduce the deviation of the tank wall boundary position caused by judging only the centroid direction of the fragment.

[0083] In one specific embodiment, the target rotor stage position is point O in the aircraft body coordinate system, with coordinates X=12.40m, Y=4.82m, and Z=-0.96m. The maximum outer edge size of the debris is 0.462m, and the scattering angle ranges from 5° backward to 5° forward. The above coordinates, dimensions, and angle ranges are used to illustrate the implementation process of this embodiment and are not intended to limit the scope of protection of this invention.

[0084] After selecting a dispersion angle within the dispersion angle range, the target rotor stage position is taken as the starting position of the debris dispersion path, and the dispersion direction of the debris from the target rotor stage position to the wing fuel tank area is determined according to the selected dispersion angle.

[0085] The divergence angle is defined within the divergence profile determined by the engine axis and the wing fuel tank reference direction. The wing fuel tank reference direction is the direction from the target rotor stage position to the geometric center of the wing fuel tank wall. When the center of the risk verification area is used as the verification input point, the wing fuel tank reference direction is determined by the direction from the target rotor stage position to the center of the risk verification area.

[0086] When determining the direction of flight dispersion, the engine axis direction and the wing fuel tank reference direction are first uniformly expressed in the aircraft body coordinate system. Then, the wing fuel tank reference direction is projected onto a plane perpendicular to the engine axis, and the projected direction is used as the reference direction for the flight dispersion direction.

[0087] The selected scatter angle is used to define the amount of deflection of the scatter direction relative to the reference direction toward the engine axis. The sign of the scatter angle is determined according to the sign convention of the forward scatter angle and the backward scatter angle in the rotor non-containment failure analysis data, thereby obtaining the scatter direction corresponding to the selected scatter angle and pointing toward the side of the wing fuel tank.

[0088] When the engine installation deflection angle and the attitude of the wing local coordinate system change, the engine axis direction and the wing fuel tank reference direction are first transformed to the aircraft body coordinate system according to the assembly coordinate transformation relationship between the engine local coordinate system, the wing local coordinate system and the aircraft body coordinate system. Then, the extension direction of the debris scattering path is determined according to the transformed engine axis direction, the transformed wing fuel tank reference direction and the selected scattering angle.

[0089] After determining the dispersion direction, the outer edge sweep range of the debris is established along the dispersion direction, and the outer edge sweep range of the debris is limited by the maximum outer edge size of the debris.

[0090] Specifically, a central reference line is formed extending from the target rotor stage position to the wing fuel tank area, with the target rotor stage position as the starting point of the central reference line and the direction of flight dispersion as the extension direction of the central reference line.

[0091] Half of the maximum outer edge size of the fragment is used as the outer boundary size of the fragment's outer edge relative to the center reference line, and an outer edge sweep body is formed along the center reference line. The outer edge sweep body is used to represent the maximum area occupied by the maximum outer edge of the fragment during the dispersion process.

[0092] When determining whether the debris dispersion path intersects with the outer contour surface of the engine nacelle, the lower surface skin of the wing, and the wing fuel tank wall, the intersection relationship between the outer edge swept body and the corresponding geometric surface is used as the basis for judgment.

[0093] When a three-dimensional digital prototype of an aircraft is represented by discrete surfaces, the closest position between the outer edge swept body and the corresponding geometric surface that meets the geometric proximity tolerance requirement is taken as the boundary position. And along the extension direction of the center reference line, the first boundary position reached is taken as the effective boundary position of the corresponding geometric surface.

[0094] For the same dispersion angle, if only the target rotor stage position and dispersion direction are used to form the center reference path, the actual intrusion range of the debris's outer edge size onto the lower wing skin and wing fuel tank wall cannot be accurately reflected. This embodiment incorporates the maximum outer edge size of the debris into the debris dispersion path determination process, enabling the debris dispersion path to reflect the debris's outer edge sweep boundary. This ensures that subsequent geometric crossing conditions, fuel dripping paths, and minimum dry compartment boundaries are all based on the risk of debris outer edge intrusion.

[0095] After determining the debris dispersion path, the dispersion direction pointing towards the wing fuel tank side is determined by the corresponding dispersion angle and taken as the extension direction of the debris dispersion path. Three types of boundary positions are then obtained along the extension direction. The three types of boundary positions include the nacelle boundary position formed by the debris dispersion path and the outer contour surface of the engine nacelle, the skin boundary position formed by the debris dispersion path and the lower surface skin of the wing, and the fuel tank wall boundary position formed by the debris dispersion path and the wing fuel tank wall.

[0096] The nacelle boundary position indicates the spatial location where debris travels away from the outer boundary of the engine nacelle. The skin boundary position indicates the spatial location where debris travels to the lower surface skin of the wing. The fuel tank wall boundary position indicates the spatial location where debris travels to the wing fuel tank wall. All three types of boundary positions are expressed in the aircraft body coordinate system, ensuring that the subsequent generation of fuel drip paths and the formation of the minimum dry compartment boundary are consistent with the unified coordinate reference in S1.

[0097] When determining the boundary positions, if multiple boundary positions exist between the debris scattering path and the same geometric surface, the first boundary position reached along the extension direction of the debris scattering path is selected as the boundary position of the corresponding geometric surface. This approach avoids interference with the boundary order determination caused by subsequent boundary positions formed by the debris scattering path and complex surfaces.

[0098] When determining the boundary position of the fuel tank wall, if the debris dispersion path forms an entry point and an exit point with the wing fuel tank wall, the boundary position where the debris enters the wing fuel tank wall is selected as the fuel tank wall boundary position along the extension direction of the debris dispersion path. This approach ensures that the fuel tank wall boundary position used to form the minimum dry compartment boundary in S5 corresponds to the risky position where debris first enters the fuel tank storage space.

[0099] In this embodiment, the dispersion angle must meet two requirements simultaneously to satisfy the geometric crossing condition. First, the nacelle junction, skin junction, and fuel tank wall junction must all exist. Second, the nacelle junction, skin junction, and fuel tank wall junction must be arranged sequentially along the extension direction of the debris dispersion path. Only when both of these requirements are met is the selected dispersion angle deemed to satisfy the geometric crossing condition.

[0100] The geometric crossing condition in this embodiment is a geometric crossing screening condition, used to determine the geometrically risky location where the outer edge of the debris sweeps across the wing fuel tank wall.

[0101] The fragment mass, fragment velocity, impact angle, skin material thickness, protective layer structure, and residual energy in the rotor non-containment failure analysis data have been used as preliminary input data to confirm that the target fragment has the necessity to enter the geometric crossing screening.

[0102] In one specific implementation, when performing S2 processing on a backward 4.0° scattering angle, a debris scattering path is formed based on the target rotor stage position, the maximum outer edge size of the debris (0.462m), and the scattering direction corresponding to a backward 4.0° scattering angle. The nacelle junction position P1, the skin junction position P2, and the fuel tank wall junction position P3 are obtained along the extension direction, where P1, P2, and P3 all exist and are arranged sequentially along the extension direction. At this point, it is determined that the backward 4.0° scattering angle satisfies the geometric crossing condition.

[0103] In this embodiment, the path distance of P1 relative to the target rotor stage position along the debris dispersion path is 0.72m, the path distance of P2 relative to the target rotor stage position along the debris dispersion path is 1.96m, and the path distance of P3 relative to the target rotor stage position along the debris dispersion path is 2.18m. Since the path distances of P1, P2, and P3 increase sequentially, it can be confirmed that the nacelle junction position, the skin junction position, and the fuel tank wall junction position are arranged sequentially along the extension direction.

[0104] In another specific embodiment, when processing the rearward 3.0° scattering angle in S2, the debris scattering path also forms the nacelle boundary, skin boundary, and fuel tank wall boundary, and these three types of boundary locations are arranged sequentially along the extension direction. Therefore, the rearward 3.0° scattering angle satisfies the geometric crossing condition. However, whether the rearward 3.0° scattering angle is a scattering angle that needs protection still needs to be further determined in S3 based on the minimum clearance distance between the fuel dripping path and the outer contour surface of the engine nacelle.

[0105] In another specific implementation, when processing the 2.0° rearward scattering angle using S2, the debris scattering path forms the nacelle boundary and the skin boundary, but not the fuel tank wall boundary. At this point, although the debris scattering path reaches the lower wing skin, it does not reach the wing fuel tank wall. Therefore, the 2.0° rearward scattering angle does not meet the geometric crossing condition and does not enter the fuel drip path generation process in S3.

[0106] In another specific implementation, when performing S2 processing on a forward 1.0° scattering angle, there is a boundary between the debris scattering path and the lower surface skin of the wing, but the nacelle boundary is not formed first along the extension direction, and the order of the nacelle boundary, skin boundary, and fuel tank wall boundary does not conform to the sequence of nacelle first, then skin, and then fuel tank wall. In this case, even if there are partial boundary locations, it is not determined that the forward 1.0° scattering angle satisfies the geometric crossing condition.

[0107] When the debris scattering path does not form a nacelle boundary with the outer contour surface of the engine nacelle, it indicates that the path does not correspond to the spatial process of non-enclosed rotor debris developing outward from the engine nacelle region; therefore, the selected scattering angle is not considered to satisfy the geometric crossing condition. When the debris scattering path forms a nacelle boundary with the outer contour surface of the engine nacelle but not a skin boundary with the lower wing skin, it indicates that the path has not reached the lower wing skin region; therefore, it does not proceed to the subsequent fuel dripping path generation step. When the debris scattering path forms boundaries with both the outer contour surface of the engine nacelle and the lower wing skin, but not a fuel tank boundary with the wing fuel tank wall, it indicates that the path has not reached the wing fuel tank wall; therefore, the geometric position corresponding to the scattering angle is not used for the minimum dry nacelle boundary formation.

[0108] To accommodate the surface discretization precision required in a 3D digital prototype of an aircraft, this embodiment employs a geometric proximity tolerance when acquiring boundary positions. The geometric proximity tolerance is used to determine whether a valid boundary position is formed between the debris scattering path and the corresponding geometric surface. In one specific implementation, the geometric proximity tolerance is set to 3 mm. When the closest distance between the debris scattering path and the outer contour surface of the engine nacelle is 2.1 mm, the corresponding closest position is considered the nacelle boundary position; when the closest distance between the debris scattering path and the wing fuel tank wall is 6.4 mm, it is not considered that a fuel tank wall boundary position has been formed.

[0109] After obtaining the nacelle boundary, skin boundary, and fuel tank wall boundary positions, this embodiment also performs a sequence check on these three types of boundary positions. The sequence check starts from the target rotor stage position and determines the sequential relationship of the three boundary positions along the extension direction of the debris dispersion path. When the nacelle boundary position precedes the skin boundary position, and the skin boundary position precedes the fuel tank wall boundary position, the three boundary positions are determined to be arranged sequentially along the extension direction.

[0110] In one exemplary result, backward angles of 5.0°, 4.5°, 4.0°, 3.5°, and 3.0° all form nacelle boundary, skin boundary, and fuel tank wall boundary positions, respectively, and these three types of boundary positions are arranged sequentially along the debris dispersion path. Therefore, all of the above dispersion angles satisfy the geometric crossing condition. A backward angle of 2.0° does not form a fuel tank wall boundary position, therefore, a backward angle of 2.0° does not satisfy the geometric crossing condition.

[0111] Example 4 Please refer to Figure 1 Specifically: In S3, the skin junction is used as the starting point for fuel dripping; The direction of fuel dripping is the direction of gravity in the aircraft's body coordinate system under the aircraft's predetermined attitude. The fuel drip path is formed by extending from the starting position of the fuel drip along the direction of fuel drip.

[0112] In S3, the minimum spatial distance between the path position on the fuel drip path and the contour position on the outer contour surface of the engine nacelle is obtained, and the minimum spatial distance is used as the minimum gap distance corresponding to the scatter angle. When the minimum gap distance is not greater than the preset safety gap, the scattering angle is determined to be a scattering angle that needs protection. When the minimum gap distance is greater than the preset safety gap, the scattering angle is determined to be a scattering angle that does not need to be protected.

[0113] In this embodiment, only scattering angles that meet the geometric crossing conditions are processed in S3. For scattering angles that do not meet the geometric crossing conditions, since their debris scattering paths do not form the required sequence of nacelle boundary, skin boundary, and fuel tank wall boundary, no fuel dripping path is generated, and the minimum clearance distance is not obtained. Through the above processing, S3 can only assess the fuel dripping risk for scattering angles that already pose a geometric crossing risk to the wing fuel tank, preventing scattering angles that do not reach the wing fuel tank wall from participating in subsequent boundary scattering angle convergence and minimum dry nacelle boundary formation.

[0114] For a scattering angle that satisfies the geometric crossing conditions, the corresponding skin boundary position is first read, and this skin boundary position is used as the starting point for fuel dripping. The skin boundary position is the spatial location formed when the debris scattering path reaches the lower surface skin of the wing, and it can characterize the initial area where fuel leakage occurs on the lower surface of the wing. Using the skin boundary position as the starting point for fuel dripping allows for a direct correspondence between the fuel dripping path and the geometric crossing result, avoiding the artificial setting of the fuel dripping starting point in an area unrelated to the geometric arrival position of the debris.

[0115] The direction of fuel dripping is determined based on the direction of gravity under the aircraft's predetermined attitude. Specifically, the pitch and roll angles corresponding to the predetermined aircraft attitude are read, and the direction of gravity is expressed in the aircraft's body coordinate system. This expressed direction is then used as the direction of fuel dripping. Since the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, and the target rotor stage position have already been unified to the aircraft's body coordinate system in Example 2, the direction of fuel dripping is also expressed in the same aircraft body coordinate system, providing a unified spatial reference for determining the distance between the fuel dripping path and the outer contour surface of the engine nacelle.

[0116] In one specific implementation, the aircraft's predetermined attitude is a safety clearance check attitude, corresponding to a pitch angle of 5.0° and a roll angle of 0°. In this attitude, the direction of gravity in the aircraft's body coordinate system is towards the underside of the wing and slightly towards the tail. This direction serves as the fuel dripping direction, representing the spatial tendency of fuel leaking from the underside of the wing and falling towards the vicinity of the engine nacelle in the predetermined aircraft attitude.

[0117] The fuel drip path is formed by extending from the starting point of the fuel drip along the direction of fuel drip. To ensure that the fuel drip path covers areas that may approach the outer contour surface of the engine nacelle, the effective extension of the fuel drip path extends at least below the lowest point of the outer contour surface of the engine nacelle. When the projection range of the outer contour surface of the engine nacelle in the direction of fuel drip is large, the effective extension of the fuel drip path extends beyond a predetermined margin from the lowest point of the outer contour surface of the engine nacelle. In this embodiment, the predetermined margin is 80 mm, used to cover the discrete errors of the three-dimensional digital prototype and the local curvature changes of the outer contour surface of the nacelle.

[0118] After generating the fuel drip path, the minimum clearance distance between the fuel drip path and the outer contour surface of the engine nacelle is obtained. Specifically, the path position is obtained on the effective extension segment of the fuel drip path, the contour position is obtained on the outer contour surface of the engine nacelle, and the minimum spatial distance between the path position and the contour position is obtained. The minimum spatial distance is used as the minimum clearance distance corresponding to that scatter angle. The minimum clearance distance is a specific distance value used to represent the degree to which the fuel drip path is closest to the outer contour surface of the engine nacelle at that scatter angle.

[0119] When the outer contour surface of the engine nacelle is a continuous curved surface, the contour position is obtained on the continuous curved surface. When the outer contour surface of the engine nacelle is expressed as a discrete mesh or discrete points in the three-dimensional digital prototype of the aircraft, the contour position is obtained on the local patch formed by the discrete mesh nodes, discrete points, and adjacent nodes, and the distance search accuracy is set according to the mesh accuracy of the three-dimensional digital prototype.

[0120] When there are multiple identical or nearly identical nearest points between the fuel drip path and the outer contour surface of the engine nacelle, the spatial distance corresponding to any one of the nearest points is taken as the minimum clearance distance. Since the subsequent judgment is based on the relationship between the minimum clearance distance and the preset safety clearance, the number of nearest points will not affect the judgment result of whether the scattering angle belongs to the scattering angle that needs protection.

[0121] In this embodiment, the preset safety clearance is 254mm. If the minimum clearance distance corresponding to a certain scattering angle is not greater than 254mm, it indicates that the spatial distance between the fuel dripping path and the outer contour surface of the engine nacelle at that scattering angle is insufficient, and there is a risk that the fuel dripping will approach the outer contour surface of the engine nacelle. Therefore, this scattering angle is determined to be a scattering angle that needs protection. A scattering angle that needs protection means that this scattering angle needs to participate in the boundary scattering angle convergence process in S4, and the boundary position of the fuel tank wall corresponding to this scattering angle needs to be used as one of the bases for forming the minimum dry compartment boundary in S5.

[0122] If the minimum clearance distance corresponding to a certain scattering angle is greater than 254mm, it indicates that the fuel dripping path and the outer contour surface of the engine nacelle at that scattering angle maintain a spatial distance greater than the preset safety clearance. Therefore, this scattering angle is determined to be a scattering angle that does not require protection. Not being a scattering angle that requires protection means that the scattering angle itself is not used as the basis for forming the minimum dry compartment boundary in S5, but this scattering angle can, in S4, together with the adjacent scattering angle that requires protection, form the two endpoints of the reduced angle interval.

[0123] When the minimum clearance distance is equal to the preset safety clearance, it is treated as not exceeding the preset safety clearance, and the corresponding scattering angle is determined to be a scattering angle that needs protection. This treatment method is used to include scattering angles on the safety boundary within the protection range, and to prevent the risk of fuel dripping under critical conditions from being excluded from the dry tank boundary design.

[0124] In one specific implementation, a backward scatter angle of 4.0° was determined in Example 3 to satisfy the geometric crossing condition, and its corresponding skin junction position is denoted as M4. M4 is taken as the starting position of fuel dripping, and a fuel dripping path L4 is formed along the fuel dripping direction. After obtaining the minimum clearance distance between the fuel dripping path L4 and the outer contour surface of the engine nacelle, the minimum clearance distance corresponding to the backward scatter angle of 4.0° is found to be 216.4 mm. Since 216.4 mm is not greater than 254 mm, the backward scatter angle of 4.0° is determined to be a scatter angle requiring protection.

[0125] In another specific embodiment, a backward scattering angle of 3.0° was also determined to meet the geometric crossing condition in Example 3, and its corresponding skin junction position was denoted as M3. M3 was taken as the starting position of fuel dripping, and a fuel dripping path L3 was formed along the fuel dripping direction. After obtaining the minimum clearance distance between the fuel dripping path L3 and the outer contour surface of the engine nacelle, the minimum clearance distance corresponding to the backward scattering angle of 3.0° was found to be 260.5 mm. Since 260.5 mm is greater than 254 mm, the backward scattering angle of 3.0° was determined to be a scattering angle that does not require protection.

[0126] In another specific embodiment, the minimum clearance distance between the fuel drip path corresponding to a backward scattering angle of 3.125° and the outer contour surface of the engine nacelle is 252.6 mm. Since 252.6 mm is not greater than 254 mm, the backward scattering angle of 3.125° is determined to be a scattering angle requiring protection. The minimum clearance distance corresponding to a backward scattering angle of 3.09375° is 254.7 mm. Since 254.7 mm is greater than 254 mm, the backward scattering angle of 3.09375° is determined not to be a scattering angle requiring protection. The above two scattering angles can be used as adjacent endpoints when the angle difference is less than the preset angle accuracy in S4 to determine the boundary scattering angle.

[0127] This embodiment can still be implemented under different predetermined aircraft attitudes. When the predetermined aircraft attitude changes, the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, and the target rotor stage position remain in the same aircraft coordinate system. The fuel dripping direction is re-determined according to the changed predetermined aircraft attitude. After re-determining the fuel dripping direction, the fuel dripping path is generated in the same way, and the minimum clearance distance is re-acquired. Therefore, this embodiment can be applied to fuel dripping risk assessment under different safety clearance verification attitudes.

[0128] Even when there are curvature variations, local protrusions, and nacelle lip edges on the outer contour surface of the engine nacelle, this embodiment still uses the minimum spatial distance between the fuel drip path and the entire outer contour surface of the engine nacelle as the minimum clearance distance, rather than limiting it to a specific preset cross-section. This approach avoids missing the nearest location due to the complex local geometry of the nacelle, ensuring that the minimum clearance distance covers the actual three-dimensional shape of the engine nacelle's outer contour surface.

[0129] When the nearest point between the fuel drip path and the outer contour surface of the engine nacelle is located in the edge region of the outer contour surface, the spatial distance corresponding to that nearest point is still used as the minimum clearance distance. If the minimum clearance distance is not greater than the preset safety clearance, the corresponding scatter angle is still determined to be a scatter angle requiring protection. This process ensures that the risk of fuel dripping near the nacelle edge is not overlooked due to its proximity to the outer contour boundary.

[0130] Example 5 Please refer to Figure 1 Specifically: In S4, multiple scattering angles to be judged are arranged in order from back to front; Among two adjacent scattering angles to be judged, if one belongs to the scattering angle that needs protection and the other does not, the two adjacent scattering angles to be judged will be used as the two endpoints of the subsequent reduction of the angle interval.

[0131] In S4, the two endpoints include the first endpoint scatter angle and the second endpoint scatter angle. The first endpoint scatter angle is a scatter angle that needs to be protected, while the second endpoint scatter angle is not a scatter angle that needs to be protected. Choose a scattering angle between the first endpoint scattering angle and the second endpoint scattering angle. The angle value of the selected scattering angle is equal to the average of the angle values ​​of the first endpoint scattering angle and the second endpoint scattering angle. When the new scattering angle is a scattering angle that needs to be protected, replace the new scattering angle with the first endpoint scattering angle, and keep the second endpoint scattering angle unchanged; When the new scattering angle is not among the scattering angles that need to be protected, replace the new scattering angle with the second endpoint scattering angle, and keep the first endpoint scattering angle unchanged; Select a new scattering angle between the replaced first endpoint scattering angle and the replaced second endpoint scattering angle, and continue to replace the endpoints in the manner that the first endpoint scattering angle is replaced when the new scattering angle is a scattering angle that needs protection, and the second endpoint scattering angle is replaced when the new scattering angle is not a scattering angle that needs protection, until the angle difference between the first endpoint scattering angle and the second endpoint scattering angle is not greater than the preset angle accuracy.

[0132] In this embodiment, multiple flyaway angles to be determined are arranged in a backward-to-forward order. This backward-to-forward order means that, using the rotor disk surface where the target rotor stage is located as the angular reference, starting from the backward flyaway angle side, the angles gradually approach the rotor disk surface and continue towards the forward flyaway angle side. This order ensures that each flyaway angle has a fixed position in the angle sequence, facilitating the identification of state changes between adjacent flyaway angles.

[0133] In one specific implementation, the initial scattering angles to be determined are selected at 0.5° intervals. The scattering angles to be determined sequentially include backward 5.0°, backward 4.5°, backward 4.0°, backward 3.5°, backward 3.0°, backward 2.5°, and backward 2.0°, and continue to extend to the forward scattering angle. Based on the minimum gap distance determination in Example 4, backward 5.0°, backward 4.5°, backward 4.0°, and backward 3.5° are scattering angles that need protection, while backward 3.0° is not.

[0134] In the above arrangement, backward 3.5° and backward 3.0° are two adjacent scattering angles to be determined. Backward 3.5° is a scattering angle that needs protection, while backward 3.0° is not; there is a change in the protection requirement between the two. Therefore, backward 3.5° is taken as the first endpoint scattering angle, and backward 3.0° is taken as the second endpoint scattering angle. The first and second endpoint scattering angles are then used as the two endpoints for subsequently reducing the angle interval.

[0135] In this embodiment, the first endpoint scatter angle is the scatter angle endpoint that needs protection, and the second endpoint scatter angle is the scatter angle endpoint that does not need protection. Maintaining the state of the two endpoints while reducing the angle interval ensures that the angle range always covers the location of the change in the state that needs protection, and reduces invalid subdivisions of the same state range.

[0136] After determining the first and second endpoint scatter angles, a new scatter angle is selected between them. The new scatter angle is equal to the average of the first and second endpoint scatter angles. Taking an initial endpoint of 3.5° and 3.0° backward as an example, the new scatter angle is 3.25° backward.

[0137] For the new scattering angle, S2 and S3 are correspondingly judged. First, the scattering path of the fragments is generated according to the new scattering angle and the geometric crossing conditions are judged. Then, the fuel dripping path is generated according to the skin junction position and the minimum gap distance is obtained. Finally, based on the relationship between the minimum gap distance and the preset safety gap, it is determined whether the new scattering angle belongs to the scattering angle that needs to be protected.

[0138] In this embodiment, the minimum clearance distance corresponding to a backward 3.25° angle is 247.1 mm. Since the preset safety clearance is 254 mm, the minimum clearance distance corresponding to a backward 3.25° angle is not greater than the preset safety clearance; therefore, a backward 3.25° angle is considered a scattering angle requiring protection. In this case, the backward 3.25° angle is replaced with the first endpoint scattering angle, while keeping the second endpoint scattering angle (backward 3.0°) unchanged. After the replacement, the first endpoint scattering angle still requires protection, while the second endpoint scattering angle does not; the angle difference between the two endpoints is reduced from 0.5° to 0.25°.

[0139] Subsequently, the first endpoint scatter angle and the second endpoint scatter angle are updated sequentially based on the minimum gap distances of 3.125°, 3.0625°, and 3.09375° backward. When the angle difference between the first endpoint scatter angle (3.125° backward) and the second endpoint scatter angle (3.09375° backward) is 0.03125°, the angle difference is not greater than the preset angle accuracy of 0.05°, and the backward 3.125° is taken as the boundary scatter angle.

[0140] In this embodiment, the rule for reducing the angle interval has definite inputs and outputs. Before each reduction, the inputs are the first endpoint scatter angle, the second endpoint scatter angle, and the angle values ​​of the two endpoints. During each reduction, a new scatter angle is first selected between the two endpoints, and then S2 and S3 are performed on the new scatter angle. After each reduction, depending on whether the new scatter angle belongs to the scatter angle requiring protection, the first endpoint scatter angle or the second endpoint scatter angle is replaced, while ensuring that the first endpoint scatter angle belongs to the scatter angle requiring protection and the second endpoint scatter angle does not.

[0141] When the new scattering angle is a scattering angle that needs protection, there is still a state change between the new scattering angle and the original second endpoint scattering angle, where one is a scattering angle that needs protection and the other is not. Therefore, replacing the first endpoint scattering angle with the new scattering angle can preserve the angle range of the boundary while reducing the angle range. When the new scattering angle is not a scattering angle that needs protection, there is still a state change between the original first endpoint scattering angle and the new scattering angle, where one is a scattering angle that needs protection and the other is not. Therefore, replacing the second endpoint scattering angle with the new scattering angle can preserve the angle range of the boundary while reducing the angle range.

[0142] In another implementation, if both adjacent scattered angles to be judged after the initial arrangement belong to the scattered angles that need protection, then they are not used as the two endpoints to reduce the angle interval, and the search for the next set of adjacent scattered angles continues in the order from back to front. If neither of the two adjacent scattered angles to be judged after the initial arrangement belongs to the scattered angles that need protection, then they are also not used as the two endpoints to reduce the angle interval, and the search continues for adjacent scattered angles with a change in the state that needs protection.

[0143] In another implementation, if more than two locations requiring protection change state appear within the dispersion angle range, the aforementioned angle reduction interval process is performed on each of these locations, and the corresponding boundary dispersion angle is obtained. For each boundary dispersion angle, the corresponding wing-fuel tank wall boundary position can be obtained in subsequent S5 to determine the corresponding minimum dry compartment boundary.

[0144] In another implementation, if there are no state change locations within the scatter angle range, and all scatter angles are not among the scatter angles requiring protection, then the angle interval reduction process is not performed, and the result that no new dry compartment isolation boundary needs to be formed within the current scatter angle range is output. If there are no state change locations within the scatter angle range, and all scatter angles are among the scatter angles requiring protection, then the two endpoint scatter angles of the scatter angle range are respectively taken as boundary scatter angles, and in subsequent S5, a minimum dry compartment boundary covering the tank wall intersection position corresponding to each scatter angle requiring protection is formed.

[0145] In this embodiment, the preset angle precision is used to control the stopping condition of the angle interval reduction process. The smaller the preset angle precision, the closer the boundary scattering angle is to the critical position of the change in the protected state, but more S2 and S3 corresponding judgments are required. The larger the preset angle precision, the fewer judgments are required, but the precision of the boundary scattering angle is reduced. In this embodiment, the preset angle precision is 0.05°, which achieves a proper balance between computational load and boundary control precision.

[0146] Through the S4 processing in this embodiment, the initial angular interval between backward 3.5° and backward 3.0° is successively reduced from 0.5° to 0.25°, 0.125°, 0.0625°, and 0.03125°. The reduction of the angular interval is limited to the adjacent scattering angles where the protection state changes, so as to reduce unnecessary angle checks and make the boundary scattering angle closer to the actual location of the change in the protection state.

[0147] Example 6 Please refer to Figure 1 Specifically: In S5, when the angle difference between the first endpoint scattering angle and the second endpoint scattering angle is not greater than the preset angle accuracy, the first endpoint scattering angle is determined as the boundary scattering angle; Obtain the boundary position between the debris scattering path corresponding to the boundary scattering angle and the wing fuel tank wall, and use the obtained boundary position as the boundary control position of the minimum dry compartment boundary; Obtain the boundary position between the debris scattering path and the wing fuel tank wall corresponding to each required scattering angle within the scattering angle range, and summarize the obtained boundary positions into a set of wing fuel tank wall boundary positions; An envelope is formed on the wing fuel tank wall. The boundary of the envelope is the control position of the envelope and the intersection position of the wing fuel tank wall. The envelope is the minimum dry compartment boundary.

[0148] In S5, adjacent rib planes that can encompass the minimum dry cabin boundary are selected based on the rib plane. The area between adjacent rib planes is the actual dry cabin area.

[0149] In this embodiment, the boundary scattering angle is used to determine the position of the protective boundary on the wing fuel tank wall. Specifically, the debris scattering path corresponding to the boundary scattering angle is read, and the intersection position between the debris scattering path and the wing fuel tank wall is obtained. The intersection position indicates the spatial position where the outer edge of the debris first reaches the wing fuel tank wall under the boundary scattering angle; therefore, the intersection position is determined as the boundary control position.

[0150] In one specific implementation, Example 5 determines a rearward 3.125° as the boundary scattering angle, and the intersection of the debris scattering path corresponding to the rearward 3.125° and the wing fuel tank wall is denoted as B0. Since the rearward 3.125° is still a scattering angle that needs protection, and the angle difference between it and the rearward 3.09375°, which is not a scattering angle that needs protection, is less than the preset angle accuracy, B0 can represent the fuel tank wall boundary position at the point where the state changes from a protected state to a non-protected state. B0 is determined as the boundary control position.

[0151] After determining the boundary control positions, the intersection positions between the debris scattering paths corresponding to each required protection scattering angle within the scattering angle range and the wing fuel tank wall are obtained. These intersection positions are then compiled into a wing fuel tank wall intersection position set. This wing fuel tank wall intersection position set represents the distribution of risk locations formed on the wing fuel tank wall for each required protection scattering angle.

[0152] In this embodiment, the set of wing-fuel tank wall boundary positions includes at least the fuel tank wall boundary positions corresponding to rearward 5.0°, rearward 4.5°, rearward 4.0°, rearward 3.5°, rearward 3.25°, and rearward 3.125°. If the debris scattering path corresponding to the same required protection scattering angle forms multiple boundary positions with the wing-fuel tank wall, then the boundary position that first reaches the wing-fuel tank wall along the extension direction of the debris scattering path is selected and added to the set of wing-fuel tank wall boundary positions.

[0153] When forming the minimum dry compartment boundary, the boundary control positions and the set of intersection positions between the wing and fuel tank walls are first expressed in the parameter domain of the wing and fuel tank walls. The parameter domain is a two-dimensional unfolded representation of the wing and fuel tank walls themselves, used to transform the intersection positions on the three-dimensional surface into two-dimensional positions that facilitate the formation of boundary lines. For the wing and fuel tank walls expressed by discrete points on the surface, the spanwise and chordwise coordinates of the fuel tank wall surface mesh can be used as the coordinates of the parameter domain.

[0154] In the parameter domain, an envelope is applied to the set of boundary control positions and the junction positions of the wing fuel tank wall, ensuring that the resulting envelope encompasses all junction positions. This envelope forms a continuous boundary line on the wing fuel tank wall that covers all junction positions requiring protection. After the envelope is formed, it is transferred from the parameter domain back to the wing fuel tank wall, serving as the minimum dry bay boundary.

[0155] In one specific implementation, the boundary positions in the set of wing-tank wall boundary positions are first sorted according to the wing spanwise position. Then, connecting segments are formed between adjacent sorted positions, and the boundaries of the local outer positions are adjusted so that the connecting segments and the boundary control positions together form an envelope that can cover all the boundary positions that need to be protected. If adjacent boundary positions are located on the same fuel tank wall surface, the connecting segment is generated along the fuel tank wall surface; if adjacent boundary positions cross two adjacent fuel tank wall surface surfaces, the connecting segment transitions along the common boundary of the two surface surfaces.

[0156] When the boundary control position is already included in the set of boundary positions of the wing fuel tank wall, the boundary control position is still treated as the control position for the formation of the envelope. This ensures that the envelope does not excessively expand into the non-protected area on the critical side where the protected state changes, and also avoids the boundary position corresponding to the boundary scattering angle being diluted by ordinary discrete boundary positions.

[0157] When the set of boundary locations between the wing and fuel tank walls is small—for example, when there is only one boundary control location and one fuel tank wall boundary location corresponding to the required dispersion angle—a boundary line connecting and covering both can still be formed on the wing and fuel tank walls. This boundary line, together with the structural boundary of the wing and fuel tank walls, defines the minimum dry compartment boundary. Therefore, even with a small number of required dispersion angles, the minimum dry compartment boundary can still be formed based on the existing boundary locations.

[0158] When multiple segments of the dispersion angle need to be protected exist within the dispersion angle range, corresponding boundary control positions and corresponding sets of wing-fuel tank wall boundary positions are formed for each segment of the dispersion angle needing protection, and corresponding envelope lines are formed for each. If multiple envelope lines approach each other on the wing-fuel tank wall within a preset merging distance, and the merged envelope line can still encompass all the boundary positions needing protection, then the corresponding envelope lines are merged into a minimum dry compartment boundary. If multiple envelope lines are separate from each other, they are each used as multiple minimum dry compartment boundaries, and the actual dry compartment area is determined separately when the wing rib plane is subsequently solidified.

[0159] In this embodiment, the minimum dry bay boundary is a calculated boundary on the wing fuel tank wall, and is not directly equivalent to the final manufacturing boundary. The minimum dry bay boundary characterizes the minimum risk area that needs to be covered by a fuel-free region under the constraints of non-enclosed rotor debris geometry crossing and fuel dripping safety clearance. To enable the minimum dry bay boundary to be implemented on the aircraft structure, it also needs to be converted into an actual dry bay area based on the rib plane.

[0160] When determining the actual dry bay area, multiple rib planes within the wing fuel tank area are read, and it is determined whether the interrib area between adjacent rib planes can encompass the minimum dry bay boundary. Encompassment means that the entire position of the minimum dry bay boundary on the wing fuel tank wall falls within the interrib area defined by adjacent rib planes; when the minimum dry bay boundary crosses a rib plane, the entire position of the minimum dry bay boundary falls within the area defined by multiple consecutive adjacent rib planes.

[0161] In one specific implementation, the minimum dry cabin boundary falls between the 7th rib plane and the 8th rib plane, and the entire position of the minimum dry cabin boundary is covered by the interrib region defined by the 7th rib plane and the 8th rib plane. Therefore, the interrib region between the 7th rib plane and the 8th rib plane is defined as the actual dry cabin region.

[0162] When the minimum dry cabin boundary crosses a rib plane, the inter-rib area of ​​a single rib cannot completely encompass the minimum dry cabin boundary. In this case, a continuous inter-rib area that can completely encompass the minimum dry cabin boundary is selected as the actual dry cabin area. For example, if the minimum dry cabin boundary crosses the 8th rib plane and falls within the range between the 7th and 9th rib planes, then the continuous inter-rib area between the 7th and 9th rib planes is determined as the actual dry cabin area.

[0163] When the minimum dry compartment boundary is close to a rib plane but does not cross it, the criterion is that it can completely encompass the minimum dry compartment boundary. If the interrib area between the 7th and 8th rib planes can encompass the minimum dry compartment boundary, it will not be expanded to the 9th rib plane. If, due to manufacturing allowances, sealing boundaries, and structural layout requirements, the interrib area between the 7th and 8th rib planes cannot completely cover the minimum dry compartment boundary, then the adjacent continuous interrib area is selected as the actual dry compartment area.

[0164] In this embodiment, after the actual dry compartment area is determined, it is marked as a fuel-free area in the three-dimensional digital prototype of the aircraft, and the fuel tank space outside the actual dry compartment area is reserved as a fuel storage area. Therefore, the output of S5 includes the calculated minimum dry compartment boundary and the actual dry compartment area that can be used for the wing fuel tank structure arrangement.

[0165] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

Claims

1. A wing tank area protection design method based on non-enclosed rotor trajectory quantification, characterized in that: Includes the following steps: S1. Obtain the outer contour of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the rib plane, the target rotor stage position, the debris characteristic size, the scattering angle range, and the fuel dripping direction in the same aircraft body coordinate system. S2. Select a dispersion angle within the dispersion angle range, and determine the corresponding fragment dispersion path according to the target rotor stage position, the fragment characteristic size and the dispersion angle. When the fragment dispersion path intersects the outer contour surface of the engine nacelle, the lower surface skin of the wing and the wing fuel tank wall in sequence along its extension direction, the dispersion angle satisfies the geometric crossing condition. In S2, the fragment feature size includes the maximum outer edge size of the fragment; The path that takes the target rotor level position in the same aircraft body coordinate system as the starting position, the scattering direction determined by the corresponding scattering angle as the extension direction, and the scattering range of the outer edge of the fragment as defined by the maximum outer edge size of the fragment is determined as the fragment scattering path. S3. Under the scattering angle that satisfies the geometric crossing conditions, the intersection of the corresponding debris scattering path and the lower surface skin of the wing is taken as the starting position of fuel dripping, and a fuel dripping path is formed along the fuel dripping direction; when the minimum distance between the fuel dripping path and the outer contour surface of the engine nacelle is not greater than the preset safety gap, the corresponding scattering angle is determined as the scattering angle that needs to be protected. S4. When one of two adjacent scattering angles belongs to the scattering angle that needs to be protected and the other does not belong to the scattering angle that needs to be protected, the angle interval between the two adjacent scattering angles is reduced, and the fragment scattering path determination and the scattering angle that needs to be protected are re-performed for the new scattering angle obtained after reducing the angle interval, until the angle interval is not greater than the preset angle accuracy, and the scattering angle that still belongs to the scattering angle that needs to be protected is taken as the boundary scattering angle. S5. The boundary control position of the fragment scattering path corresponding to the boundary scattering angle and the wing fuel tank wall is taken as the boundary control position of the minimum dry compartment boundary. The minimum dry compartment boundary is formed by the boundary control position and the wing fuel tank wall boundary position corresponding to each scattering angle to be protected. The actual dry compartment area that encompasses the minimum dry compartment boundary is determined according to the wing rib plane.

2. The non-enclosure rotor trajectory quantification based wing tank area protection design method according to claim 1, characterized in that: In S1, the whole-aircraft reference coordinate system in the three-dimensional digital prototype of the aircraft is used as the aircraft body coordinate system. Under the same aircraft body coordinate system, the outer contour surface of the engine nacelle, the lower surface skin of the wing, the wing fuel tank wall, the wing rib plane and the position of the target rotor stage are obtained. The fragment characteristic size and the scattering angle range are obtained from the rotor non-containment failure analysis data corresponding to the target rotor stage position; The direction of the fuel dripping is determined based on the direction of gravity in the aircraft's coordinate system under the aircraft's predetermined attitude.

3. The non-enclosure rotor trajectory quantification based wing tank area protection design method according to claim 1, characterized in that: In S2, the extending direction is the dispersion direction determined by the corresponding dispersion angle and pointing towards the side of the wing fuel tank; Along the extension direction, the intersection position of the debris dispersion path and the nacelle boundary formed by the outer contour surface of the engine nacelle is obtained sequentially; The location where the debris dispersion path intersects with the skin formed by the lower surface skin of the wing; The location where the debris scattering path intersects with the fuel tank wall formed by the wing fuel tank wall; When the nacelle junction, the skin junction, and the fuel tank wall junction all exist and are arranged sequentially along the extension direction, the dispersion angle is determined to satisfy the geometric crossing condition.

4. The non-enclosure rotor trajectory quantification based wing tank area protection design method according to claim 3, characterized in that: In S3, the skin junction is taken as the starting position of fuel dripping; The direction of the fuel dripping is the direction of the gravity direction in the aircraft's body coordinate system under the aircraft's predetermined attitude. The fuel dripping path is formed by extending from the starting position of the fuel dripping along the direction of the fuel dripping.

5. The non-enclosure rotor trajectory quantification based wing tank area protection design method according to claim 4, characterized in that: In S3, the minimum spatial distance between the path position on the fuel drip path and the contour position on the outer contour surface of the engine nacelle is obtained, and the minimum spatial distance is used as the minimum gap distance corresponding to the scattering angle. When the minimum gap distance is not greater than the preset safety gap, the scattering angle is determined as the scattering angle that needs to be protected. When the minimum gap distance is greater than the preset safety gap, the scattering angle is determined to be a scattering angle that does not require protection.

6. The non-enclosure-rotor trajectory quantization based wing tank area protection design method according to claim 5, characterized in that: In S4, multiple scattering angles to be determined are arranged in order from back to front; Among two adjacent scattering angles to be judged, if one belongs to the scattering angle that needs protection and the other does not, the two adjacent scattering angles to be judged will be used as the two endpoints of the subsequent reduction of the angle interval.

7. The non-enclosure-rotor trajectory quantization based wing tank area protection design method according to claim 6, characterized in that: In S4, the two endpoints include a first endpoint scatter angle and a second endpoint scatter angle, where the first endpoint scatter angle belongs to the scatter angle that needs to be protected, and the second endpoint scatter angle does not belong to the scatter angle that needs to be protected. A scattering angle is selected between the first endpoint scattering angle and the second endpoint scattering angle, and the angle value of the selected scattering angle is equal to the average value of the angle values ​​of the first endpoint scattering angle and the second endpoint scattering angle. When the new scattering angle belongs to the scattering angle that needs to be protected, the new scattering angle is replaced with the first endpoint scattering angle, while the second endpoint scattering angle remains unchanged; When the new scattering angle does not belong to the scattering angle that needs to be protected, the new scattering angle is replaced with the second endpoint scattering angle, while the first endpoint scattering angle remains unchanged; A new scattering angle is selected between the replaced first endpoint scattering angle and the replaced second endpoint scattering angle. The endpoint replacement is then performed in the manner that the first endpoint scattering angle is replaced when the new scattering angle belongs to the scattering angle that needs to be protected, and the second endpoint scattering angle is replaced when the new scattering angle does not belong to the scattering angle that needs to be protected, until the angle difference between the first endpoint scattering angle and the second endpoint scattering angle is not greater than the preset angle accuracy.

8. The non-enclosure rotor trajectory quantification based wing tank area protection design method according to claim 7, characterized in that: In S5, when the angle difference between the first endpoint scattering angle and the second endpoint scattering angle is not greater than the preset angle accuracy, the first endpoint scattering angle is determined as the boundary scattering angle. Obtain the boundary position between the debris scattering path corresponding to the boundary scattering angle and the wing fuel tank wall, and use the obtained boundary position as the boundary control position of the minimum dry compartment boundary; Obtain the boundary position between the debris scattering path corresponding to each required scattering angle within the scattering angle range and the wing fuel tank wall, and summarize the obtained boundary positions into a set of wing fuel tank wall boundary positions; An envelope is formed on the wall of the wing fuel tank, which encloses the set of boundary control positions and the junction of the wing fuel tank wall, and the envelope is the minimum dry compartment boundary.

9. The wing fuel tank area protection design method based on non-containment rotor trajectory quantization according to claim 7, characterized in that: In S5, an adjacent rib plane that can encompass the minimum dry cabin boundary is selected based on the rib plane. The interrib region between adjacent rib planes is the actual dry cabin region.

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