A method, system, medium and product for determining the installation position of a nose ice detector based on the height of the water droplet shielding area

Abstract

The present invention belongs to the field of numerical simulation and post-processing, and specifically discloses a method, system, medium, and product for determining the installation position of an aircraft nose ice detector based on the height of the water droplet shielding area. The method comprises: selecting several sections perpendicular to the fuselage centerline at the nose, determining the water droplet shielding area height at each section, and then obtaining the overall water droplet shielding area height of the nose through interpolation; screening areas on the nose surface where the water droplet shielding area height is less than the length of the ice detector probe as feasible installation locations; and determining the water droplet shielding area height at a certain section, including: interpolating and encrypting the LWC distribution scatter plot at the section, screening out data points that meet the water droplet shielding area requirements, and extracting their upper and lower envelopes; interpolating and encrypting both the upper and lower envelopes, and then determining the water droplet shielding area height at the section based on the water droplet shielding area heights of all points on the upper envelope. The present invention can achieve accurate installation of the aircraft nose ice detector and improve its detection accuracy.

Description

Technical Field

[0001] The present invention belongs to the field of numerical simulation and post-processing, and more specifically, relates to a method, system, medium and product for determining the installation position of a nose ice detector based on the height of a water droplet shielding area. Background Art

[0002] When an aircraft flies in icing conditions, supercooled water droplets suspended in the airstream have greater mass and inertia than air particles, so they develop their own circumferential motion paths. Supercooled water droplets of varying sizes experience different forces in the airflow, leading to different motion paths in the airstream. Small droplets, with less inertia, do not significantly deviate from streamlines and thus avoid impacting the wing. Larger droplets, however, have greater inertia and are more likely to deviate from streamlines, resulting in impacts. Figure 1 This figure shows three water droplets of different sizes flowing over an airplane wing from the same point at the same speed. Drop C is the smallest, with less inertia and less deviation from the airstream, bypassing the wing without impacting it. Drops A and B, however, impact the wing surface.

[0003] The impact of supercooled water droplets on the aircraft surface is the cause of aircraft icing. Therefore, the prediction of water droplet motion and surface impact is the most basic and important part of icing calculations, and is also the prerequisite for ice shape calculation and anti-icing system design.

[0004] All water droplets from the far flow field correspond to a motion trajectory, so when they move relative to the wing, they form a trajectory cluster, such as Figure 2 As shown in Figure 2. Among the clusters of water droplet trajectories, there are two trajectories that are tangent to the upper and lower surfaces of the wing respectively. All water droplets within these two tangent trajectories collide with the wing surface; while all water droplets outside the two tangent trajectories bypass the wing and do not collide with the wing surface. Therefore, the wing surface surrounded by the two tangent trajectories (such as Figure 2 The water droplet impact zone (S) is called the droplet impact area. The amount of water droplets impacting the wing surface within two tangent trajectories is called the droplet impact volume. During aircraft icing and de-icing, the impact area where supercooled water droplets impact the aircraft surface, the impact volume within the impact area, and its distribution are commonly referred to as droplet impact characteristics.

[0005] The inertia of water droplets causes some water droplets to hit the wall, and the wall forms a water drop shielding effect on the rear. There are no water droplets in this area, which is called the water drop shielding area. Figure 2 As shown in the figure, the area behind the airfoil without track lines indicates zero liquid water content. The thickness and extent of the water droplet shielding zone also require analysis of water droplet impact characteristics, which primarily influences the installation location of devices such as pitot tubes, temperature sensors, ice detectors, and antennas.

[0006] To ensure the reliability of the ice detection signal, the probe must be located outside the water droplet shielding zone. Therefore, it is necessary to quickly and accurately determine the nose ice detector's water droplet shielding zone, thereby ensuring accurate installation and improving detection accuracy. Summary of the Invention

[0007] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a method, system, medium and product for determining the installation position of the nose ice detector based on the height of the water droplet shielding area, the purpose of which is to achieve accurate installation of the nose ice detector and improve its detection accuracy.

[0008] To achieve the above objectives, according to a first aspect of the present invention, a method for determining the installation position of a nose ice detector based on the height of a water droplet shielding zone is proposed, comprising the following steps:

[0009] Several sections perpendicular to the fuselage's mid-axis were selected at the nose of the aircraft. The water droplet shielding area height at each section was determined, and then the overall water droplet shielding area height of the nose was obtained through interpolation. Areas on the nose surface where the water droplet shielding area height was less than the length of the ice detector rod were selected as feasible installation locations for the ice detector.

[0010] Determining the height of the water droplet shielding area at a certain cross section includes the following steps:

[0011] The LWC distribution scatter plot at the cross section is interpolated and encrypted, and then the data points that meet the water droplet shielding area requirements are screened out;

[0012] Based on the data points that meet the requirements of the water droplet shielding area, the upper and lower envelopes are extracted, where the upper envelope represents the outer contour of the water droplet shielding area, and the lower envelope represents the inner contour of the water droplet shielding area, that is, the surface of the nose;

[0013] The upper and lower envelope lines are interpolated and encrypted; then for each point on the upper envelope line: find the point on the lower envelope line that is closest to it as the pairing point, and use this distance as the minimum distance to determine the normal vector at the pairing point on the nose surface, and use the component of the minimum distance in the direction of the normal vector as the height of the water droplet shielding area; determine the height of the water droplet shielding area at the cross section based on the height of the water droplet shielding area of ​​all points on the upper envelope line.

[0014] As a further preference, the selected several cross sections are distributed from behind the radar cabin to before the cabin door.

[0015] As a further preference, three longitudinal sections are selected at the nose, wherein the first section is 100 mm behind the radar cabin, the third section is 100 mm before the cabin door, and the second section is located between the first and third sections.

[0016] As a further preferred method, based on the screened data points that meet the water droplet shielding area requirements, extracting the upper and lower envelopes thereof includes:

[0017] The data points that meet the requirements of the water droplet shielding area are divided into several groups in sequence. The outermost point in each group of data points is used as the point on the upper envelope line, and the innermost point is used as the point on the lower envelope line, thereby obtaining the upper and lower envelope lines.

[0018] As a further preferred method, a scatter plot of LWC distribution at each cross section is obtained in advance, including:

[0019] The flow field outside the nose is simulated to obtain the distribution of liquid water content around the nose, that is, the grid points of the nose and the corresponding LWC values, and thus the LWC distribution scatter plot at each cross section is obtained.

[0020] As a further preferred method, screening the data points in the LWC distribution scatter plot that meet the water droplet shielding area requirements includes:

[0021] The nose grid points with LWC values ​​less than the incoming flow LWC value determined when simulating the flow field outside the nose are regarded as data points that meet the requirements of the water droplet shielding area.

[0022] According to a second aspect of the present invention, a system for determining the installation position of an aircraft nose ice detector based on the height of a water droplet shielding area is provided, comprising a processor for executing the above-mentioned method for determining the installation position of an aircraft nose ice detector based on the height of a water droplet shielding area.

[0023] According to a third aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area is implemented.

[0024] According to a fourth aspect of the present invention, a computer program product is provided, which includes a computer program, and when the computer program is executed by a processor, it implements the above-mentioned method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area.

[0025] In general, the above technical solutions conceived by the present invention have the following technical advantages compared with the existing technology:

[0026] 1. This invention determines the water droplet shielding zone height based on a LWC distribution scatter plot, while also taking into account the effect of installation angle on the shielding zone height, making the shielding zone height calculation result closer to reality. This allows for automated calculation of the water droplet shielding zone height distribution on the aircraft nose surface, which can be used as a basis for determining the ice detector installation location, improving its detection accuracy.

[0027] 2. The present invention utilizes the interpolation method to reduce the burden of grid division in numerical simulation and improve the accuracy of simulation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of water droplets of different sizes flowing over a wing according to an embodiment of the present invention;

[0029] Figure 2 This is a diagram of water droplet trajectories on the airfoil surface according to an embodiment of the present invention;

[0030] Figure 3 This is a flow chart of a method for determining the installation position of a nose ice detector based on the height of a water droplet shielding zone according to an embodiment of the present invention;

[0031] Figure 4 This is a scatter plot of LWC distribution in an embodiment of the present invention;

[0032] Figure 5 This is a contour diagram of the water droplet shielding area according to an embodiment of the present invention;

[0033] Figure 6 This is a diagram showing the interpolation effect of the water droplet occlusion area according to an embodiment of the present invention;

[0034] Figure 7 Schematic diagram of the upper and lower envelopes of the water droplet shielding area according to an embodiment of the present invention;

[0035] Figure 8 This is an enlarged view of the upper and lower envelopes of the water droplet shielding area according to an embodiment of the present invention;

[0036] Figure 9 Schematic diagram of the distance matrix of points on the inner and outer contours of the water droplet shielding area according to an embodiment of the present invention;

[0037] Figure 10 2. This is a graph showing the height distribution of the water droplet shielding area according to an embodiment of the present invention;

[0038] Figure 11 2. This is a schematic diagram of solving the height of the water droplet shielding area in the normal direction according to an embodiment of the present invention;

[0039] Figure 12 2. This is a schematic diagram of the grid coordinates on the surface of the nose of an embodiment of the present invention;

[0040] Figure 13 Schematic diagram of the nose point cloud and unit normal vector according to an embodiment of the present invention;

[0041] Figure 14 This is a comparison diagram of the shielding area height calculated by considering the installation angle in the embodiment of the present invention.

[0042] Figure 15 Schematic diagram of a typical cross section of the surface of the handpiece according to an embodiment of the present invention;

[0043] Figure 16 (a) and (b) are schematic diagrams of the height distribution of the shielded area on the entire surface of the nose before and after interpolation in an embodiment of the present invention;

[0044] Figure 17 This is a schematic diagram of the installation position of the ice detector according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0046] The embodiment of the present invention provides a method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area, such as Figure 3 As shown, the following steps are included:

[0047] (1) Select a typical cross section of the nose:

[0048] Select several sections perpendicular to the fuselage's mid-axis at the nose of the aircraft, each section distributed from behind the radar cabin to before the cabin door. For each section, determine the height of its water droplet shielding area according to steps (2) to (5).

[0049] Preferably, three typical sections are determined according to the position of the radome hatch. Section 1 is selected 100 mm behind the radar cabin, section 3 is selected 100 mm before the hatch, and section 2 is located between sections 1 and 3. Figure 15 shown.

[0050] (2) Numerical simulation of the water droplet flow field distribution at the nose:

[0051] The CFD method is used to simulate the flow field outside the nose and obtain the liquid water content distribution around the nose. The numerical simulation results and grid coordinates are extracted, and the liquid water content value (i.e., LWC value) and the coordinates of the nose grid points are exported to form a list file. The grid data is stored in a matrix for batch operation, and the exported LWC data is post-processed. First, a scatter plot of the LWC distribution of each required section is drawn, as shown in the figure. Figure 4 As shown, the scattered points are distributed according to the grid node coordinates, and the color of the scattered points represents the size of the LWC value.

[0052] (3) Screening the data points in the LWC distribution scatter plot that meet the water droplet shielding area requirements;

[0053] The mesh and liquid water content data from the previous step are interpolated and encrypted using an algorithm. Because the derived scattered point data is affected by the mesh size, under certain operating conditions, the scattered points in the obscured area may be too sparse. In this case, interpolation can be used to encrypt the scattered points in the obscured area to make the shape more defined and facilitate fitting. After interpolation, the LWC values ​​of the data points are used to select points that meet the requirements for the water droplet obscured area. In other words, the LWC values ​​of the obscured area data points must be less than the LWC of the incoming flow, which is determined by the LWC value of the aircraft's flight environment.

[0054] If we filter directly without interpolation, the data points of the water droplet shielding area are as follows: Figure 5 As shown, the data points of the water droplet occlusion area obtained after interpolation and screening are as follows Figure 6 shown.

[0055] (4) Extraction of upper and lower envelopes of data points in the water droplet shielding area:

[0056] The idea of ​​grouping scattered points is adopted. According to the total number of scattered points, the scattered points are divided into several groups. In each group of scattered points, the outermost and innermost scattered points are found as the point sets of the upper and lower envelope lines respectively. The upper envelope line represents the outer contour of the water droplet shielding area, and the lower envelope line represents the inner contour of the water droplet shielding area, that is, the surface of the nose.

[0057] Specifically, a spatial rectangular coordinate system is constructed with the fuselage centerline as the X-axis, the vertical ground direction as the Y-axis, and the normal direction of the nose symmetry plane as the Z-axis. To find the height distribution of the shielded area, it is first necessary to draw the envelope of the scattered points in the shielded area. The solution of the envelope adopts the idea of ​​grouping the scattered points. According to the total number of scattered points, the scattered points are divided into several groups (usually 300 to 500 points per group) according to the position order in the Y-axis direction. In each group of scattered points, the maximum and minimum values ​​in the Z-axis direction are found as points on the upper and lower envelopes respectively; the envelope solution result is as follows: Figure 7 As shown, Figure 8 This is a partial enlarged view of the envelope line.

[0058] (5) Solving the height of the water droplet shielding area in the cross section:

[0059] Interpolate the upper and lower envelopes separately. For each point on the upper envelope, find the closest point on the lower envelope as a pairing point, using this distance as the minimum distance. Then, determine the normal vector at the paired point on the nose surface, and use the component of the minimum distance in the direction of this normal vector as the height of the water droplet obscuration. The height of the water droplet obscuration for all points on the upper envelope is the height of the water droplet obscuration at the cross section.

[0060] In actual implementation, it can be understood as Figure 7 Interpolate 10,000 points on the inner and outer contour curves shown, and loop through the points on the inner and outer contours to obtain the distance matrix, as shown in the figure. Figure 9As shown. The result is a 10000×10000 matrix. The minimum value of each column in the matrix is ​​the distance from the point on the outer contour of the water droplet shielding area to the nose wing surface. The coordinate corresponding to this minimum distance in the matrix can be found. From this, a curve graph of the height of the water droplet shielding area along the Y direction can be drawn, as shown Figure 10 As shown, Figure 10 The horizontal axis represents the Y direction, and the vertical axis represents the height of the water droplet shielding area.

[0061] Then, the coordinates of the minimum distance on the nose surface are found according to the position of the minimum distance in the matrix, the normal vector of the corresponding nose surface is extracted, and the component of the minimum distance along the normal vector direction is calculated, which is the height of the water droplet occlusion area at this point.

[0062] Specifically, since the ice detector is installed perpendicular to the nose surface of the aircraft, the shielding area height calculated by the cross section perpendicular to the fuselage centerline as shown in the figure will be somewhat different from the actual result, such as Figure 11 Therefore, in order to make the shielding area height closer to the actual situation, it is necessary to consider the installation angle to accurately process the shielding area height. First, export the mesh of the nose surface in Fluent, as shown in Figure 12 As shown; then write the XYZ data of the scattered points on the head into the pcd file to generate the point cloud of the head surface, and then use the correlation function of the point cloud to calculate the unit normal vector corresponding to each point on the head, and store them in the matrix in order. The generated head point cloud and normal vector diagram are shown as follows Figure 13 shown.

[0063] To calculate the actual shielding area height from the unit vector matrix, we must first find the normal vector coordinates closest to the nose surface point on the shielding area section to be calculated, and then calculate the component of the original shielding area height in that direction, and then we can draw a two-dimensional graph of the new shielding area height with respect to the Y coordinate. The comparison of the shielding area height considering the installation angle and the two-dimensional calculated shielding area height is shown in the figure below. Figure 14 As shown in the figure, the height of the shielding area varies from 3% to 25% depending on the installation location.

[0064] (6) Interpolation calculation of the height distribution of the water droplet shielding area on the head surface:

[0065] After obtaining the height of the water droplet shielding area of ​​each section, interpolation is performed between the three sections to obtain the height of the water droplet shielding area of ​​the entire nose, such as Figure 16 As shown in the figure, the color depth represents the height of the water droplet shielding area.

[0066] (7) Screening ice detector installation location:

[0067] According to the solution of the water droplet shielding area height and the length of the ice detector probe, the area on the nose surface where the water droplet shielding area height is less than the probe rod length is selected as the ice detector installation location. Figure 17 To filter the results based on the ice detector rod length of 0.1m, the filled area in the figure is the possible installation location of the ice detector.

[0068] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for determining the installation position of a nose ice detector based on the height of a water droplet shielding zone, characterized in that: The steps include: Several sections perpendicular to the fuselage's mid-axis were selected at the nose of the aircraft. The water droplet shielding area height at each section was determined, and then the overall water droplet shielding area height of the nose was obtained through interpolation. Areas on the nose surface where the water droplet shielding area height was less than the length of the ice detector rod were selected as feasible installation locations for the ice detector. Determining the height of the water droplet shielding area at a certain cross section includes the following steps: The LWC distribution scatter plot at the cross section is interpolated and encrypted, and then the data points that meet the water droplet shielding area requirements are screened out; Based on the data points that meet the requirements of the water droplet shielding area, the upper and lower envelopes are extracted, where the upper envelope represents the outer contour of the water droplet shielding area, and the lower envelope represents the inner contour of the water droplet shielding area, that is, the surface of the nose; The upper and lower envelope lines are interpolated and encrypted; then for each point on the upper envelope line: find the point on the lower envelope line that is closest to it as the pairing point, and use this distance as the minimum distance to determine the normal vector at the pairing point on the nose surface, and use the component of the minimum distance in the direction of the normal vector as the height of the water droplet shielding area; determine the height of the water droplet shielding area at the cross section based on the height of the water droplet shielding area of ​​all points on the upper envelope line.

2. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding zone according to claim 1, characterized in that: The selected sections are distributed from behind the radar cabin to before the cabin door.

3. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding zone according to claim 2, characterized in that: Three longitudinal sections are selected at the nose of the aircraft, wherein the first section is 100 mm behind the radar cabin, the third section is 100 mm before the cabin door, and the second section is located between the first and third sections.

4. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding zone according to claim 1, characterized in that: Based on the selected data points that meet the requirements of the water droplet shielding area, extract the upper and lower envelopes, including: The data points that meet the requirements of the water droplet shielding area are divided into several groups in sequence. The outermost point in each group of data points is used as the point on the upper envelope line, and the innermost point is used as the point on the lower envelope line, thereby obtaining the upper and lower envelope lines.

5. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding zone according to any one of claims 1 to 4, characterized in that: Obtain the LWC distribution scatter plot at each section in advance, including: The flow field outside the nose is simulated to obtain the distribution of liquid water content around the nose, that is, the grid points of the nose and the corresponding LWC values, and thus the LWC distribution scatter plot at each cross section is obtained.

6. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding zone according to claim 5, characterized in that: Filter the data points in the LWC distribution scatter plot that meet the water droplet shielding area requirements, including: The nose grid points with LWC values ​​less than the incoming flow LWC value determined when simulating the flow field outside the nose are regarded as data points that meet the requirements of the water droplet shielding area.

7. A system for determining the installation position of a nose ice detector based on the height of a water droplet shielding zone, characterized in that: The method comprises a processor configured to execute the method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area according to any one of claims 1 to 6.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area according to any one of claims 1 to 6 is implemented.

9. A computer program product, characterized in that The method comprises a computer program, which, when executed by a processor, implements the method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area as described in any one of claims 1 to 6.

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