Safety assessment method for eVTOL aircraft crossing runway extension line

Abstract

The invention relates to the field of aircraft safety operation evaluation, and particularly discloses a safety evaluation method for an eVTOL aircraft crossing a runway extension line, and the method comprises the steps: S1, calculating the safety interval of the eVTOL in the lateral and vertical directions, determining the size parameter of a crossing region, calculating the minimum safety interval of a civil aircraft and the eVTOL, and calculating the safety interval of the eVTOL according to the size parameter of the crossing region and the minimum safety interval; determining the position of a crossing area; s2, comprehensively evaluating the position scheme of the crossing area from three safety evaluation dimensions of traffic alarm and anti-collision system alarm logic, collision risk of the civil aircraft and eVTOL in the crossing area and civil aircraft tail vortex sinking influence; and S3, if the position of the crossing area meets the requirements of the three evaluation dimensions in the step S2 at the same time, judging that the position of the crossing area reaches the standard in safety evaluation, and outputting the position of the crossing area. According to the method, multiple safety assessment dimensions are comprehensively considered, and the safety of the crossing area is improved.

Description

Technical Field

[0001] This invention relates to the field of aircraft safety operation assessment, and more particularly to a safety assessment method for eVTOL aircraft crossing runway extensions. Background Technology

[0002] eVTOL (electric vertical take-off and landing aircraft), as an emerging mode of transportation, is expected to take on the task of passenger transfer between cities and airports in the future, thereby effectively alleviating ground traffic pressure and significantly improving travel efficiency. However, considering the potential impact that eVTOLs may have on the normal operation and flight safety of civil aircraft during operation, it is crucial to set up scientifically reasonable crossing zones to better meet future operational needs.

[0003] Currently, most existing methods for assessing the safety of eVTOL integrated operations with civil aircraft analyze only a single factor. This one-sided approach makes the assessment results lack sufficient persuasiveness. At the same time, there is a lack of research in the crucial area of ​​ensuring the safe operation of eVTOL in airport areas by setting up crossing zones, which urgently needs further in-depth research. Summary of the Invention

[0004] This invention aims to address the problems of unreasonable crossing zone settings and a single dimension in the safety assessment of the integrated operation of eVTOL and civil aircraft. To this end, this invention provides a safety assessment method for eVTOL aircraft crossing runway extensions. This method can calculate lateral and vertical safety separations based on eVTOL, obtain the dimensional parameters of the crossing zone, determine the minimum safe separation between the crossing zone and the runway glide slope based on the frequency of traffic alert and collision avoidance system (TRAS) warning events, and set the crossing zone location. It comprehensively considers the impact of multiple dimensions, including the frequency of TRAS warning events, the collision risk between manned aircraft and eVTOL, and the wake vortex of manned aircraft. This invention improves the safety of eVTOL aircraft crossing runway extensions and provides a reference for the future integrated operation of manned aircraft and eVTOL within airport areas.

[0005] This invention provides a safety assessment method for eVTOL aircraft crossing runway extensions, and the technical solution adopted is as follows: including the following steps: S1: Based on the eVTOL performance parameters, calculate the required safety clearance in the lateral and vertical directions, and determine the size parameters of the crossing area, specifically the length and width; Calculate the minimum safe separation between the civil aircraft and the eVTOL, and determine the location of the crossing zone based on the crossing zone size parameters and the minimum safe separation; S2: Based on the alarm logic of the traffic alarm and collision avoidance system, construct an alarm judgment simulation model, count the frequency of civil aircraft alarms triggered by eVTOL in the crossing area, and determine whether the alarm frequency is lower than the preset safety threshold. A collision risk model between civil aircraft and eVTOLs in the crossing zone is constructed. Based on the model, the collision risk value in the crossing zone is calculated, and it is determined whether the value is lower than the safety target threshold. Construct a model of the tail vortex of a civil aircraft, calculate its tail vortex descending height, and determine whether the height is higher than the upper limit of the height of the crossing zone; S3: If the crossing area location simultaneously meets the evaluation requirements of the three dimensions in step S2 above, it is determined to be a crossing area location that meets the safety assessment criteria, and the crossing area location and evaluation result are output; when the safety assessment fails to meet the criteria, the crossing area size parameters are adjusted based on experience according to the reasons for failure, and the crossing area location is reset.

[0006] Furthermore, based on the eVTOL's performance parameters, the required safety separations in the lateral and vertical directions are calculated. The length of the crossing zone is determined based on the lateral safety separation between aircraft, and the width of the crossing zone is determined based on the vertical safety separation between aircraft, including: S11: The formula for calculating the probability of overlap between aircraft in the lateral direction is: in, This represents the probability of overlap between aircraft in the lateral direction. The lateral spacing between aircraft. This represents the boundary value of the lateral protection zone in the negative direction. This represents the boundary value of the lateral protection zone in the positive direction. This represents the combined standard deviation of the lateral positioning error. This represents the deviation between the actual interval and the expected interval. The formula for calculating the probability of overlap between aircraft in the vertical direction is: in, This represents the probability of overlap between aircraft in the vertical direction. The vertical spacing between aircraft. This represents the boundary value of the vertically protected area in the negative direction. This represents the boundary value of the vertically protected area in the positive direction. The combined standard deviation of the vertical positioning error; S12: The formula for calculating the risk of collision in the lateral direction is: in, To mitigate the risk of lateral collisions, The loss rate per flight hour in the lateral direction. The probability of vertical overlap when the vertical spacing is zero. E ( s () represents the vertical proximity rate. For the fuselage length of eVTOL, For the eVTOL's chassis width, For the height of eVTOL, The longitudinal spacing between aircraft. The relative speed between civil aircraft and eVTOL in the longitudinal direction, The relative speed between civil aircraft and eVTOL in the lateral direction, The relative speed between the civil aircraft and the eVTOL in the vertical direction; The calculation formula is: The formula for calculating collision risk in the vertical direction is: in, For the risk of collision in the vertical direction, The vertical loss rate per flight hour interval. This represents the probability density function when the vertical error between aircraft is zero. The probability of lateral overlap when the lateral spacing is zero; The calculation formula is: S13: Set up the iterative calculation process, starting from the initial interval, adjust the interval parameters in the lateral and vertical directions, substitute the adjusted interval values ​​into the formula to calculate the collision risk. When the collision risk is equal to or lower than the civil aviation safety target level, the corresponding lateral and vertical interval parameters are the minimum crossing zone size parameters that meet the safety requirements.

[0007] Furthermore, the minimum safe separation between the civil aircraft and the eVTOL is calculated. Based on the crossing zone size parameters and the minimum safe separation, the location of the crossing zone is determined, including: Formula for calculating the altitude of a civil aircraft on the runway glide slope: in, For civilian aircraft altitude, This refers to the elevation of the runway entrance. For reference point height, This refers to the horizontal distance between a civilian aircraft and the runway threshold. The length of the runway. The glide angle of the runway glide slope; Alarm boundary calculation formula: in, For alarm boundaries, This is the TCAS alarm threshold. For fixed interval parameters, For variable warning thresholds, Current altitude; Formula for calculating runway glide slope height: in, The runway glide slope height, This represents the horizontal position of the current calculation point. The horizontal position of the runway glide slope reference point, usually located at the runway entrance; The difference between the height of a civil aircraft on the runway glide path and the warning boundary is the minimum safe separation. The eVTOL crossing zone is located below the alarm boundary, and the optimal location of the crossing zone within the range below the alarm boundary is determined by the following method: taking into account the distance between the crossing zone and the runway and the minimum height of the crossing zone, the optimal location is selected based on ensuring the minimum safe distance.

[0008] Furthermore, based on the alarm logic of the traffic alarm and collision avoidance system, an alarm determination simulation model is constructed; The construction of the alarm determination simulation model includes: importing the eVTOL's navigation data, performance data, and external wind disturbance data, and simulating various operating states of the eVTOL in the crossing area using the Monte Carlo method; Based on the alarm judgment simulation model and the various operating states generated by the simulation, the alarm frequency of eVTOL and civil aircraft is counted. If the alarm frequency is lower than the preset safety threshold, the safety of the crossing area location scheme is determined to meet the requirements.

[0009] Furthermore, the collision risk model calculation process for civil aircraft and eVTOLs within the crossing zone is as follows: Formula for calculating horizontal overlap probability: in, The longitudinal spacing between aircraft. The lateral spacing between aircraft. This represents the horizontal overlap probability. The relative velocity on the horizontal plane, The horizontal collision rate; Formula for calculating the probability of vertical crossing: in, Let be the probability of vertical crossing. The vertical spacing between aircraft. The minimum safety interval threshold, The attenuation scaling factor. For the vertical height of civil aircraft, The vertical height of eVTOL; System reliability calculation: Formula for calculating collision risk in the vertical direction: in, This represents the collision risk value in the vertical direction. This represents the probability of overlap within the horizontal plane. The vertical relative velocity, The height of the collision box for civil aircraft. The height of the eVTOL collision box; Formula for calculating the probability of collision risk: in, The probability of collision risk. To assess the effectiveness of drone collision avoidance systems, To assess the reliability of ATC's intervention in conflicts. For the reliability of TCAS, For the reliability of collision avoidance by manned aircraft pilots, For the reliability of STCA; Collision risk calculation formula: in, This represents the collision risk value. This is the environmental impact coefficient, under ideal environmental conditions. When encountering severe weather, , This is the coefficient representing the impact of airspace management on collision risk; when control measures can effectively avoid collisions, When control measures are ineffective in avoiding a collision, .

[0010] Furthermore, the calculation process for the civil aircraft tail vortex downdraft model includes: S21: Calculation of basic parameters; S22: Construction of circulation decay model; S23: Construction of the wake vortex downsinking model.

[0011] Furthermore, the basic parameter calculation process includes: S211: Initial vortex spacing calculation formula: in, is the initial vortex spacing, and B is the aircraft wingspan; S212: Initial circulation calculation formula: in, This is the initial circulation. For aircraft quality, air density, For aircraft speed; S213: Formula for calculating wake sinking velocity: in, This refers to the wake sinking velocity; S214: Parameter normalization calculation formula: in, This represents the actual turbulent dissipation rate. The normalized turbulent dissipation rate, This is the actual BV frequency. For the normalized BV frequency, For normalized time.

[0012] Furthermore, the construction of the circulation decay model includes: S221: Diffusion stage: in, For dimensionless time, The average circulation is for a wake radius of 5-15m. The amplitude is a constant. It is a constant related to the average integral radius. This marks the start time of the first phase. The effective viscosity for the first stage; S222: Rapid decay phase: in, This marks the start time of the second phase. The effective viscosity for the second stage is given by the following formula: in, For dimensional time, For dimensionless time, This is the reference time for the rapid decay phase.

[0013] Furthermore, the construction of the wake vortex downsinking model includes: in, Indicates time, The sinking velocity of the wake vortex. The time-varying amount of the wake vortex is denoted as . This represents the sinking height of the vortex core.

[0014] Furthermore, step S3 includes: If the location of the crossing zone simultaneously meets the following three conditions: eVTOL triggered alarms on civil aircraft less frequently than the preset safety threshold; The collision risk value between civil aircraft and eVTOL is lower than the safety target threshold; The tail vortex of the civilian aircraft descends to a height exceeding the upper limit of the altitude range it traverses. The system determines that the safety assessment of the crossing area meets the standards, generates a safety assessment compliance signal, and outputs the geographic coordinates of the crossing area.

[0015] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1. This invention provides a safety assessment method for eVTOL aircraft crossing runway extensions. It innovatively conducts a comprehensive assessment of the safety of the crossing area from multiple key dimensions, providing a scientific and reliable reference for the future integrated operation of manned aircraft and eVTOL within the airport area, and ensuring the safety of the two types of aircraft operating together from multiple dimensions.

[0016] 2. This invention calculates the safety intervals of the eVTOL in the lateral and vertical directions to obtain the dimensional parameters of the crossing zone and sets the location of the crossing zone. Simultaneously, it innovatively incorporates three core dimensions for consideration: the frequency of traffic alert and collision avoidance system warning events, the risk of collision between manned aircraft and the eVTOL, and the wake vortex of manned aircraft. This forms a multi-faceted safety assurance system, effectively improving the safety performance of the crossing zone and laying the foundation for the safe operation of the eVTOL in complex environments.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the method provided by the present invention.

[0020] Figure 2 This is a schematic diagram illustrating the changes in collision risk of heavy composite wings (eVTOL).

[0021] Figure 3 This is a diagram showing the layout of the crossing zone.

[0022] Figure 4 This is a diagram illustrating an alarm triggered by eVTOL.

[0023] Figure 5 This is a schematic diagram showing the distribution of violations at the alarm boundary.

[0024] Figure 6 This is a schematic diagram illustrating how collision risk changes with vertical spacing.

[0025] Figure 7 This is a diagram illustrating the distribution of collision risks.

[0026] Figure 8 This is a schematic diagram illustrating the impact of the wake vortex on the crossing area. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. The following embodiments are used to illustrate this invention but should not be used to limit the scope of this invention.

[0028] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0029] The following is combined Figures 1 to 8 The present invention will be further described in detail below, including a method for safety assessment of an eVTOL aircraft crossing a runway extension: In this embodiment, as Figure 1 As shown, a safety assessment method for a typical compound wing eVTOL aircraft crossing a runway extension is provided, including the following steps: S1: Based on the eVTOL performance parameters, calculate the required safety clearance in the lateral and vertical directions, and determine the crossing zone size parameters, specifically including length and width.

[0030] Based on the eVTOL's performance parameters, calculate the required lateral and vertical safety separations between it and manned aircraft. Determine the length of the crossing zone based on the lateral safety separations between aircraft, and determine the width of the crossing zone based on the vertical safety separations between aircraft, including: S11: The formula for calculating the probability of overlap between aircraft in the lateral direction is: in, This represents the probability of overlap between aircraft in the lateral direction. The lateral spacing between aircraft. This represents the boundary value of the lateral protection zone in the negative direction. This represents the boundary value of the lateral protection zone in the positive direction. This represents the combined standard deviation of the lateral positioning error. This represents the deviation between the actual interval and the expected interval. The formula for calculating the probability of overlap between aircraft in the vertical direction is: in, This represents the probability of overlap between aircraft in the vertical direction. The vertical spacing between aircraft. This represents the boundary value of the vertically protected area in the negative direction. This represents the boundary value of the vertically protected area in the positive direction. The combined standard deviation of the vertical positioning error; S12: The formula for calculating the risk of collision in the lateral direction is: in, To mitigate the risk of lateral collisions, The loss rate per flight hour in the lateral direction. The probability of vertical overlap when the vertical spacing is zero. E ( s () represents the vertical proximity rate. For the fuselage length of eVTOL, For the eVTOL's chassis width, For the height of eVTOL, The longitudinal spacing between aircraft. The relative speed between civil aircraft and eVTOL in the longitudinal direction, The relative speed between civil aircraft and eVTOL in the lateral direction, The relative speed between the civil aircraft and the eVTOL in the vertical direction; The calculation formula is: The formula for calculating collision risk in the vertical direction is: in, For the risk of collision in the vertical direction, The vertical loss rate per flight hour interval. This represents the probability density function when the vertical error between aircraft is zero. The probability of lateral overlap when the lateral spacing is zero; The calculation formula is: .

[0031] Based on the typical compound wing eVTOL, the safety clearances in the lateral and vertical directions are calculated to obtain the dimensional parameters of the crossing zone. The relevant parameters of the heavy compound wing under low-precision conditions are shown in Table 1, and the relevant parameters of the collision model are shown in Table 2.

[0032] Table 1

[0033] Table 2

[0034] Under low-precision navigation conditions, the safety target level set for the heavy-duty compound wing eVTOL is 10. -9 Based on the collision risk formula in step S1, an iterative calculation process is set up. Starting from the initial interval, the interval parameters in the lateral and vertical directions are adjusted. The adjusted interval values ​​are substituted into the formula to calculate the collision risk. When the collision risk is equal to or lower than the civil aviation safety target level, the corresponding lateral and vertical interval parameters are the minimum crossing zone size parameters that meet the safety requirements.

[0035] Figure 2 (a) represents the side collision risk of the heavy composite wing eVTOL. Figure 2 (b) represents the vertical collision risk. The collision risk exhibits a clear pattern as the lateral and vertical clearances change: the smaller the clearance, the higher the collision risk. When the collision risk is reduced to the safety target level of 10... -9 At that time, the corresponding lateral clearance is 75m and the vertical clearance is 24.6m. This indicates that in order for the heavy composite wing eVTOL to achieve this safety target in terms of collision risk, its lateral clearance must be no less than 75m and its vertical clearance no less than 24.6m.

[0036] Based on the frequency of traffic alerts and collision avoidance system warnings, calculate the minimum safe separation required between the crossing area and the runway glide slope, including: Formula for calculating the altitude of a civil aircraft on the runway glide slope: in, For civilian aircraft altitude, This refers to the elevation of the runway entrance. For reference point height, This refers to the horizontal distance between a civilian aircraft and the runway threshold. The length of the runway. The glide angle of the runway glide slope; Alarm boundary calculation formula: in, For alarm boundaries, This is the TCAS alarm threshold. For fixed interval parameters, For variable warning thresholds, Current altitude; Formula for calculating runway glide slope height: in, The runway glide slope height, This represents the horizontal position of the current calculation point. The horizontal position of the runway glide slope reference point, usually located at the runway entrance; The difference between the height of a civil aircraft on the runway glide path and the warning boundary is the minimum safe separation.

[0037] Based on the crossing zone size parameters and minimum safety interval, the crossing zone location is generated. Airport-related parameters are shown in Table 3, alarm rate levels are shown in Table 4, and eVTOL crossing zone-related parameters are set in Table 5.

[0038] eVTOL crossing zone, such as Figure 3 As shown, the blue solid line represents the aircraft glide slope, the green line represents the warning boundary, and the height of both lines increases linearly with distance. The red line represents the crossing zone. The eVTOL crossing zone is located below the warning boundary, and the optimal location of the crossing zone within the area below the warning boundary is determined as follows: Based on ensuring the minimum safe separation, the optimal location is obtained by comprehensively considering the distance between the crossing zone and the runway, and the minimum height of the crossing zone.

[0039] Table 3 Table 4

[0040] Table 5

[0041] S2: Based on the alarm logic of the traffic alarm and collision avoidance system, construct an alarm judgment simulation model, count the frequency of civil aircraft alarms triggered by eVTOL in the crossing area, and determine whether the alarm frequency is lower than the preset safety threshold.

[0042] A Monte Carlo simulation experiment was conducted, generating an eVTOL position uniformly distributed within the crossing zone each time. Random errors from three aspects—eVTOL navigation and positioning, flight performance factors, and wind disturbance factors—were introduced to simulate real-world conditions. The scenario where eVTOLs trigger warnings on civil aircraft during crossing zones is as follows: Figure 4 As shown, the red dot is near the warning boundary, indicating a violation location.

[0043] Based on the alarm judgment simulation model and various simulated operating states, the alarm frequency of eVTOL and civil aircraft-triggered alarms is statistically analyzed. If the alarm frequency is lower than a preset safety threshold, the safety of the crossing area location scheme is determined to meet the requirements. The spatial distribution of alarm points is as follows: Figure 5 As shown, there were 18 alarm points in 2 million experiments, with an alarm rate of 9 × 10⁻⁶. -6The distance between the aircraft and the eVTOL is less than the set level requiring mitigation measures, and the maximum violation alarm boundary value for the eVTOL is 25.6 ft. The minimum vertical distance between the civil aircraft and the eVTOL is 341.3 m, which is greater than the minimum safe separation requirement between passenger aircraft. This verifies that under ideal conditions, the eVTOL flying within the set crossing zone will not affect the approach of the passenger aircraft or trigger an alarm on the civil aircraft.

[0044] A collision risk model between a civil aircraft and an eVTOL within the crossing zone is constructed. Based on this model, the collision risk value within the crossing zone is calculated, and it is determined whether this value is lower than the safety target threshold to analyze the safety of the crossing zone. The calculation process of the collision risk model between a civil aircraft and an eVTOL within the crossing zone is as follows: Formula for calculating horizontal overlap probability: in, The longitudinal spacing between aircraft. The lateral spacing between aircraft. This represents the horizontal overlap probability. The relative velocity on the horizontal plane, The horizontal collision rate; Formula for calculating the probability of vertical crossing: in, Let be the probability of vertical crossing. The vertical spacing between aircraft. The minimum safety interval threshold, The attenuation scaling factor. For the vertical height of civil aircraft, The vertical height of eVTOL; System reliability calculation: Formula for calculating collision risk in the vertical direction: in, This represents the collision risk value in the vertical direction. This represents the probability of overlap within the horizontal plane. The vertical relative velocity, The height of the collision box for civil aircraft. The height of the eVTOL collision box; Formula for calculating the probability of collision risk: in, The probability of collision risk. To assess the effectiveness of drone collision avoidance systems, To assess the reliability of ATC's intervention in conflicts. For the reliability of TCAS, For the reliability of collision avoidance by manned aircraft pilots, For the reliability of STCA; Collision risk calculation formula: in, This represents the collision risk value. This is the environmental impact coefficient, under ideal environmental conditions. When encountering severe weather, , This is the coefficient representing the impact of airspace management on collision risk; when control measures can effectively avoid collisions, When control measures are ineffective in avoiding a collision, .

[0045] System reliability parameters are shown in Table 6, aircraft speed parameters in Table 7, collision box parameters in Table 8, and collision model parameters in Table 9. The safety target level is set to 1×10⁻⁶. -7 Incident / flight hours.

[0046] Table 6

[0047] Table 7

[0048] Table 8

[0049] Table 9

[0050] Among them, V x1 V is the longitudinal speed of a civil aircraft. x2 V is the velocity of eVTOL in the longitudinal direction. y1 V is the lateral speed of the civil aircraft. y2 Let V be the lateral velocity of eVTOL. z1 V is the vertical speed of the civil aircraft. z2 Let eVTOL be the velocity in the vertical direction. The length of the collision box of the civil aircraft. The length of the eVTOL collision box For the width of the civil aircraft collision box, The width of the eVTOL collision box. The height of the collision box for civil aircraft. This is the height of the eVTOL collision box.

[0051] After 1 million Monte Carlo experiments, considering the navigation error of vertical eVTOL, the results are as follows: Figure 6 , Figure 7 As shown, the collision risk gradually decreases with increasing vertical spacing, and the average collision risk is... The value is less than the safety target level, which verifies that the setting of the crossing zone is safe at this time.

[0052] A model of the civil aircraft's wake vortex downturn is constructed to calculate its downturn height and determine whether this height exceeds the upper limit of the height of the crossing area. The calculation process of the civil aircraft wake vortex downturn model includes: The basic parameter calculation process includes: S211: Initial vortex spacing calculation formula: in, is the initial vortex spacing, and B is the aircraft wingspan; S212: Initial circulation calculation formula: in, This is the initial circulation. For aircraft quality, air density, For aircraft speed; S213: Formula for calculating wake sinking velocity: in, This refers to the wake sinking velocity; S214: Parameter normalization calculation formula: in, This represents the actual turbulent dissipation rate. The normalized turbulent dissipation rate, This is the actual BV frequency. For the normalized BV frequency, For normalized time.

[0053] Construction of circulation decay model: S221: Diffusion stage: in, For dimensionless time, The average circulation is for a wake radius of 5-15m. The amplitude is a constant. It is a constant related to the average integral radius. This marks the start time of the first phase. The effective viscosity for the first stage; S222: Rapid decay phase: in, This marks the start time of the second phase. The effective viscosity for the second stage is given by the following formula: in, For dimensional time, For dimensionless time, This is the reference time for the rapid decay phase.

[0054] The construction of the wake vortex downsinking model includes: in, Indicates time, The time-varying amount of the wake vortex is denoted as . The sinking velocity of the wake vortex. This represents the sinking height of the vortex core.

[0055] Taking the A380 civil aircraft as an example, the influence of its tail vortex downslope height on the eVTOL crossing zone is analyzed. The relevant parameters of the A380 aircraft are shown in Table 10, and the relevant parameters of the tail vortex downslope model are shown in Table 11.

[0056] Table 10

[0057] Table 11

[0058] Simulation analysis was conducted on two typical wakes exhibiting significant differences in their two-stage evolution characteristics. The first type is characterized by a longer dissipation time in the first stage, while the second type is characterized by a longer dissipation time in the second stage. Furthermore, the two types of wakes show significant differences in their descent height throughout the entire evolution process. To further refine the spatial distribution of the wakes, interpolation was performed on the wakes around the crossing area. The results are as follows: Figure 8 As shown, the changes in runway glide slope height, wake height, and the range of intrusion into the danger zone are presented at different distances.

[0059] This invention proposes a safety assessment method for eVTOL aircraft crossing runway extensions, which comprehensively considers the safety of setting up crossing zones from three aspects, providing a reference for the future integrated operation of manned aircraft and eVTOL within airport areas.

[0060] Through mathematical analysis of the constructed model, it was found that in terms of alarms, there were 18 alarm points in 2 million experiments, with an alarm rate of If the risk level is lower than the set mitigation level, eVTOL flying within the designated crossing zone will not affect the approach of the passenger aircraft or trigger a warning on the passenger aircraft. Regarding collision risk, the average collision risk between the passenger aircraft and eVTOL in 1 million experiments is [missing information]. The value is less than the safety target level, which verifies that the crossing zone setting is safe at this time; in terms of the impact of manned aircraft wake vortices, the wake vortices generated by civil aircraft flying on the runway glide slope will not affect the flight of eVTOL in the crossing zone.

[0061] This invention solves the problems of unreasonable crossing zone settings and a single dimension for evaluating the safety of eVTOL and civil aircraft integrated operation, improves the safety of crossing zones, and provides a reference for the future integrated operation of manned aircraft and eVTOL within airport areas.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A safety assessment method for an eVTOL aircraft crossing a runway extension, characterized in that, Includes the following steps: S1: Based on the eVTOL performance parameters, calculate the required safety clearance in the lateral and vertical directions, and determine the crossing zone size parameters; Calculate the minimum safe separation between the civil aircraft and the eVTOL, and determine the location of the crossing zone based on the crossing zone size parameters and the minimum safe separation; S2: Based on the alarm logic of the traffic alarm and collision avoidance system, construct an alarm judgment simulation model, count the frequency of civil aircraft alarms triggered by eVTOL in the crossing area, and determine whether the alarm frequency is lower than the preset safety threshold. A collision risk model between a civil aircraft and an eVTOL in the crossing area is constructed. Based on this model, the collision risk value in the crossing area is calculated, and it is determined whether the value is lower than the safety target threshold. Construct a model of the tail vortex of a civil aircraft, calculate its tail vortex descent height, and determine whether the height is higher than the upper limit of the height of the crossing area. S3: If the location of the crossing area simultaneously meets the evaluation requirements of the three dimensions in step S2 above, it is determined to be a crossing area location that meets the safety assessment standards, and the crossing area location and evaluation result are output.

2. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 1, characterized in that, Based on the eVTOL's performance parameters, calculate the required safety separations in the lateral and vertical directions. Determine the length of the crossing zone based on the lateral safety separations between aircraft, and determine the width of the crossing zone based on the vertical safety separations between aircraft, including: S11: Calculate the probability of overlap between aircraft in the lateral and vertical directions; S12: Calculate the collision risk in the lateral and vertical directions; S13: Set up the iterative calculation process, starting from the initial interval, adjust the interval parameters in the lateral and vertical directions, substitute the adjusted interval values ​​into the formula to calculate the collision risk. When the collision risk is equal to or lower than the civil aviation safety target level, the corresponding lateral and vertical interval parameters are the minimum crossing zone size parameters that meet the safety requirements.

3. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 1, characterized in that, Calculate the minimum safe separation between the civil aircraft and the eVTOL, and determine the location of the crossing zone based on the crossing zone size parameters and the minimum safe separation, including: Formula for calculating the altitude of a civil aircraft on the runway glide slope: in, For civilian aircraft altitude, This refers to the elevation of the runway entrance. For reference point height, This refers to the horizontal distance between a civilian aircraft and the runway threshold. The length of the runway. The glide angle of the runway glide slope; Alarm boundary calculation formula: in, For alarm boundaries, This is the TCAS alarm threshold. For fixed interval parameters, For variable warning thresholds, Current altitude; Formula for calculating runway glide slope height: in, The runway glide slope height, This represents the horizontal position of the current calculation point. The horizontal position of the runway glide slope reference point, usually located at the runway entrance; The difference between the height of a civil aircraft on the runway glide path and the warning boundary is the minimum safe separation. The eVTOL crossing zone is located below the alarm boundary, and the optimal location of the crossing zone within the range below the alarm boundary is determined by the following method: taking into account the distance between the crossing zone and the runway and the minimum height of the crossing zone, the optimal location is selected based on ensuring the minimum safe distance.

4. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 1, characterized in that, Based on the alarm logic of the traffic alarm and collision avoidance system, an alarm determination simulation model is constructed. The construction of the alarm determination simulation model includes: importing the eVTOL's navigation data, performance data, and external wind disturbance data, and simulating various operating states of the eVTOL in the crossing area using the Monte Carlo method; Based on the alarm judgment simulation model and the various operating states generated by the simulation, the alarm frequency of eVTOL and civil aircraft is counted. If the alarm frequency is lower than the preset safety threshold, the safety of the crossing area location scheme is determined to meet the requirements.

5. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 1, characterized in that, The collision risk model calculation process between the civil aircraft and the eVTOL in the crossing zone is as follows: Formula for calculating horizontal overlap probability: in, This represents the horizontal overlap probability. The longitudinal spacing between aircraft. The lateral spacing between aircraft. The relative velocity on the horizontal plane, The horizontal collision rate; Formula for calculating the probability of vertical crossing: in, Let be the probability of vertical crossing. The vertical spacing between aircraft. The minimum safety interval threshold, The attenuation scaling factor. For the vertical height of civil aircraft, The vertical height of eVTOL; System reliability calculation: Formula for calculating collision risk in the vertical direction: in, This represents the collision risk value in the vertical direction. This represents the probability of overlap within the horizontal plane. The vertical relative velocity, The height of the collision box for civil aircraft. The height of the eVTOL collision box; Formula for calculating the probability of collision risk: in, The probability of collision risk. To assess the effectiveness of drone collision avoidance systems, To assess the reliability of ATC's intervention in conflicts. For the reliability of TCAS, For the reliability of collision avoidance by manned aircraft pilots, For the reliability of STCA; Collision risk calculation formula: in, This represents the collision risk value. This is the environmental impact factor. This is the coefficient representing the impact of airspace management on collision risk.

6. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 1, characterized in that, The calculation process for the civil aircraft tail vortex downdraft model includes: S21: Calculation of basic parameters; S22: Construction of circulation decay model; S23: Construction of the wake vortex downsinking model.

7. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 6, characterized in that, The basic parameter calculation process includes: S211: Calculate the initial vortex spacing; S212: Calculate the initial circulation; S213: Calculate the wake sinking velocity; S214: Calculate the normalization parameter.

8. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 6, characterized in that, The construction of the circulation decay model includes: S221: Diffusion stage: in, The average circulation is for a wake radius of 5-15m. For dimensionless time, The amplitude is a constant. It is a constant related to the average integral radius. This marks the start time of the first phase. The effective viscosity for the first stage; S222: Rapid decay phase: in, This marks the start time of the second phase. The effective viscosity for the second stage is given by the following formula: in, For dimensional time, For dimensionless time, This is the reference time for the rapid decay phase.

9. A safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 6, characterized in that, The construction of the wake vortex downsinking model includes: in, The time-varying amount of the wake vortex is denoted as . Indicates time, This is the initial circulation. Let B be the velocity of the wake vortex, and B be the wingspan of the aircraft. This represents the sinking height of the vortex core.

10. The safety assessment method for an eVTOL aircraft crossing a runway extension as described in claim 1, characterized in that, Step S3 includes: If the location of the crossing zone simultaneously meets the following three conditions: eVTOL triggered alarms on civil aircraft less frequently than the preset safety threshold; The collision risk value between civil aircraft and eVTOL is lower than the safety target threshold; The tail vortex of the civilian aircraft descends to a height exceeding the upper limit of the altitude range it traverses. The system determines that the safety assessment of the crossing area meets the standards, generates a safety assessment compliance signal, and outputs the geographic coordinates of the crossing area.

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