Method and system for determining installation position of machine head icing detector based on height of water drop shielding area, medium and product

Abstract

The invention belongs to the field of numerical simulation and post-processing, and particularly discloses a method and system for determining the installation position of a machine head icing detector based on the height of a water drop shielding area, a medium and a product, and the method comprises the steps: selecting a plurality of sections perpendicular to the central axis of a machine body at a machine head, determining the height of the water drop shielding area at each section, and determining the installation position of the machine head icing detector; obtaining the height of the whole water drop shielding area of the machine head through interpolation; screening an area with the height of a water drop shielding area smaller than the length of a probe rod of the icing detector on the surface of the machine head as a feasible mounting position; determining the height of a water drop shielding area at a certain cross section: performing interpolation encryption on an LWC distribution scatter diagram at the cross section, screening out data points meeting the requirements of the water drop shielding area, and extracting upper and lower envelope lines of the data points; and performing interpolation encryption on the upper envelope line and the lower envelope line, and determining the height of the water drop shielding area at the cross section according to the heights of the water drop shielding areas of all points on the upper envelope line. Accurate installation of the machine head icing detector can be achieved, and the detection accuracy of the machine head icing detector is improved.

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 airplane flies under icing weather conditions, the supercooled water droplets suspended in the airflow have a greater mass and inertia than air particles, so the water droplets will form their own circumferential motion trajectory. Supercooled water droplets of different sizes in the air have different motion trajectories in the airflow due to different forces. If the water droplets are very small, their inertia is also small, so the small water droplets will not deviate significantly from the streamline and will not hit the wing surface; larger water droplets have greater inertia and are more likely to deviate from the streamline, thus hitting the wing. Figure 1 It shows the situation where three water droplets of different sizes flow over the wing at the same speed and from the same point. C is the smallest droplet with small inertia and small deviation from the air streamline, bypassing the wing without hitting it; A and B droplets hit 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 movement and surface impact is the most basic and important part of icing calculation, and it is also the premise of ice shape calculation and anti-icing system design.

[0004] All water droplets from the far flow field correspond to a motion trajectory, so when moving relative to the wing, a trajectory cluster is formed, such as Figure 2 As shown in Figure 1. In the cluster 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 area on the wing surface is called the impact amount of the water droplet on the wing surface. The amount of water droplets that impact on the wing surface within two tangent trajectories is called the impact amount of the water droplet on the wing surface. During the icing and de-icing process of the aircraft, the impact area of ​​the supercooled water droplets on the aircraft surface, the impact amount and distribution of the surface in the impact area are usually called the water 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, there is no track line in the rear part of the airfoil, and the liquid water content in this area is zero. The thickness and range of the water droplet shielding area also need to be obtained through the analysis of the water droplet impact characteristics, which mainly affects the selection of the installation position of the pitot tube, temperature sensor, ice signal, antenna and other devices.

[0006] To ensure the reliability of the ice detection working signal, the probe should be located outside the water droplet shielding area. Therefore, it is necessary to quickly and accurately determine the nose water droplet shielding area for the nose ice detector, so as to achieve accurate installation of the nose ice detector and improve detection accuracy. Summary of the invention

[0007] In response to the above 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, which aims to achieve accurate installation of the nose ice detector and improve its detection accuracy.

[0008] To achieve the above object, 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] Select several sections perpendicular to the fuselage centerline at the nose, determine the height of the water droplet shielding area at each section, and then obtain the overall water droplet shielding area height of the nose by interpolation; select the area on the nose surface where the water droplet shielding area height is less than the length of the ice detector probe rod as the feasible installation position of the ice detector;

[0010] The step of 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 requirements of the water droplet shielding area are screened out;

[0012] Based on the selected 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 envelopes are interpolated and encrypted; then for each point on the upper envelope: find the point on the lower envelope that is closest to it as the pairing point, and use this distance as the minimum distance, and then 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.

[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 section and the third section.

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

[0017] The screened data points that meet the requirements of the water droplet shielding area are divided into several groups in order. 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 LWC distribution scatter plot 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, so as to obtain the LWC distribution scatter plot at each cross section.

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

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

[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, wherein the processor is used to execute 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, there is provided a computer-readable storage medium having a computer program stored thereon, wherein 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, there is provided a computer program product, which includes a computer program, and 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.

[0025] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0026] 1. The present invention determines the height of the water droplet shielding area based on the LWC distribution scatter plot, and considers the influence of the installation angle on the height of the shielding area, so that the calculation result of the height of the shielding area is closer to the actual situation. The automatic solution of the height distribution of the water droplet shielding area on the head surface can be realized, and the installation position of the ice detector can be determined based on this, thereby 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 is a water droplet trajectory diagram on the airfoil surface of an embodiment of the present invention;

[0030] Figure 3 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 area according to an embodiment of the present invention;

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

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

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

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

[0036] Fig. 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] Fig.10 is a water drop shielding area height distribution curve diagram of an embodiment of the present invention;

[0038] Fig.11 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] Fig.12 is a schematic diagram of grid coordinates on the surface of a machine head according to an embodiment of the present invention;

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

[0041] Fig.14 This is a comparison diagram of the shielding area height calculated by considering the shielding area height section of the installation angle according to the embodiment of the present invention.

[0042] Fig.15 Schematic diagram of a typical cross section of the surface of the machine head according to an embodiment of the present invention;

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

[0044] Fig.17 It 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 purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain 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 can be combined with each other as long as they do not conflict with each other.

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

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

[0048] Select several cross sections perpendicular to the fuselage centerline at the nose, each of which is distributed from behind the radar cabin to before the cabin door. For each cross 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 section 1 and section 3. Fig.15 shown.

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

[0051] The CFD method is used to simulate the flow field outside the nose and obtain the distribution of liquid water content 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, draw the LWC distribution scatter plot of each required section, such as Figure 4 As shown, the scattered points are distributed according to the grid node coordinates, and the color of the scattered points indicates the size of the LWC value.

[0052] (3) Filter 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 values ​​from the previous step are encrypted by algorithm interpolation. Because the derived scattered point data is affected by the mesh size, the scattered points in the shielded area may be too sparse under certain working conditions. In this case, the interpolation method can be used to encrypt the scattered points in the shielded area to make its shape clearer and easier to fit. After interpolation, the points that meet the requirements of the water droplet shielding area are selected according to the LWC value of the data point, that is, the LWC value of the shielded area data point must be less than the incoming flow LWC, and the incoming flow LWC is determined according to the LWC value in the environment when the aircraft is flying.

[0054] If we directly filter without interpolation, we can get the data points of the water droplet shielding area as follows: Figure 5 As shown in the figure, 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, the centerline of the fuselage is taken as the X-axis, the direction perpendicular to the ground is taken as the Y-axis, and the normal direction of the nose symmetry plane is taken as the Z-axis to construct a spatial rectangular coordinate system. In order to obtain 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 obtained as the 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) Determination of the height of the water droplet shielding area in the cross section:

[0059] Interpolate the upper and lower envelopes respectively. For each point on the upper envelope: find the point on the lower envelope that is closest to it as the pairing point, and use this distance as the minimum distance, and then 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. The height of the water droplet shielding area of ​​all points on the upper envelope is the height of the water droplet shielding area 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 Fig. 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, and the coordinates of this distance on the nose surface can be found from the position of the minimum distance in the matrix. From this, a curve graph of the height of the water droplet shielding area along the Y direction can be drawn, as shown Fig.10 As shown, Fig.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 from 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 shielding area at this point.

[0062] Specifically, since the ice detector is installed perpendicular to the nose surface of the aircraft, the height of the shielded area calculated by the cross section perpendicular to the centerline of the fuselage as shown in the figure will be somewhat different from the actual result, such as Fig.11 So in order to make the height of the shielded area closer to the actual situation, it is necessary to consider the installation angle to accurately process the height of the shielded area. First, export the mesh of the nose surface in Fluent, as shown in Fig.12 As shown; then write the XYZ data of the scattered points of 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 in Fig.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 this direction, so that 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: Fig.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 Fig.16 As shown in the figure, the color depth represents the height of the water droplet shielding area.

[0066] (7) Screening of 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. Fig.17 To filter the results based on the ice detector rod length of 0.1m, the filled area in the figure is the location where the ice detector can be installed.

[0068] It will be easily understood by those skilled in the art that the above description is only 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 protection scope 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 area, characterized in that: The steps include: Select several sections perpendicular to the fuselage centerline at the nose, determine the height of the water droplet shielding area at each section, and then obtain the overall water droplet shielding area height of the nose by interpolation; select the area on the nose surface where the water droplet shielding area height is less than the length of the ice detector probe rod as the feasible installation position of 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 requirements of the water droplet shielding area are screened out; Based on the selected 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 envelopes are interpolated and encrypted; then for each point on the upper envelope: find the point on the lower envelope that is closest to it as the pairing point, and use this distance as the minimum distance, and then 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.

2. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area 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 area according to claim 2, characterized in that: 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.

4. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area 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 screened data points that meet the requirements of the water droplet shielding area are divided into several groups in order. 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 area according to any one of claims 1 to 4, characterized in that: The LWC distribution scatter plot at each section is obtained 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, so as to obtain the LWC distribution scatter plot at each cross section.

6. The method for determining the installation position of the nose ice detector based on the height of the water droplet shielding area 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 whose LWC values ​​are smaller than the incoming flow LWC values ​​are taken as data points that meet the requirements of the water droplet shielding area. The incoming flow LWC values ​​are determined when simulating the flow field outside the nose.

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: It includes a processor, which is used to execute 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.

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 as described in any one of claims 1 to 6 is implemented.

9. A computer program product, characterized in that It includes 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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