A method for converting two-dimensional icing patterns of aircraft wings into three-dimensional icing patterns.

Abstract

This invention belongs to the field of aviation icing research and relates to a method for converting two-dimensional icing patterns of aircraft wings into three-dimensional icing patterns. The method includes: selecting the icing pattern with the greatest aerodynamic influence from the profile icing patterns obtained from icing wind tunnel tests; simplifying the selected icing pattern based on aerodynamic similarity; and generating three-dimensional icing patterns for different wing surfaces from the simplified icing pattern through methods such as icing pattern contour translation, bridging, surface filling, and extrapolation extension.

Description

Technical Field

[0001] This invention belongs to the field of aviation icing research and relates to a method for converting two-dimensional icing patterns on aircraft wings into three-dimensional icing patterns. Background Technology

[0002] According to the similarity criteria for wind tunnel testing of aircraft wing icing, icing wind tunnel tests typically use full-size wing component models or hybrid scaled-down models with full-size leading edges. Due to wind tunnel size limitations, only icing tests on partial wing sections can be conducted. Ice pattern measurements in wind tunnel tests are usually performed using the "hot knife method." During measurement, a heated metal plate is used to melt the ice on the measurement section, and then a plastic plate is used in conjunction with graph paper to sketch the ice pattern outline, obtaining a two-dimensional test ice pattern of the measurement section. Approximately three measurement sections are typically set up for each test piece. In summary, the ice pattern obtained from wind tunnel tests is only a two-dimensional ice pattern of different parts of a portion of the wing surface. Research on the aerodynamic effects of aircraft wing icing requires converting the obtained two-dimensional ice pattern into a three-dimensional ice pattern covering the entire leading edge of the wing.

[0003] To ensure the authenticity of the three-dimensional ice shape effect after conversion, the following issues need to be addressed during the ice shape conversion process: (1) The two-dimensional ice shape obtained from the ice wind tunnel test is irregular. Usually, the ice shape needs to be simplified before conversion to reduce the difficulty of three-dimensional conversion of the ice shape and subsequent simulation ice shape model processing. Simplifying the ice shape cannot change the aerodynamic influence of the original ice shape; (2) The two-dimensional ice shapes obtained from different positions of the same test piece usually have differences. In the ice shape conversion, it is necessary to consider how to handle the differences in ice shapes at different positions; (3) The chord length and thickness of the airfoil usually have differences along the span. When icing, the trajectory of water droplets and the impact area will have differences, which will lead to differences in ice shape. In the ice shape conversion, it is necessary to consider how to handle the differences in ice shape caused by the change in the airfoil shape. Summary of the Invention

[0004] The purpose of this invention is to propose a method for converting two-dimensional icing patterns on aircraft wings into three-dimensional icing patterns, thereby solving the problem of three-dimensional conversion of wind tunnel test results for aircraft wing icing.

[0005] Technical solution:

[0006] A method for converting two-dimensional icing patterns of aircraft wings into three-dimensional icing patterns is proposed, including:

[0007] The ice type with the greatest aerodynamic influence was selected from the ice profiles obtained from the ice wind tunnel test.

[0008] The selected ice shapes are simplified based on aerodynamic similarity;

[0009] By using methods such as ice shape contour translation, bridging or surface filling, and extrapolation extension, the simplified ice shape is used to generate three-dimensional ice shapes with different airfoils.

[0010] Furthermore, from the ice profiles obtained from the ice wind tunnel tests, the ice types with the greatest aerodynamic influence were selected, including:

[0011] The ice type with the greatest impact on the aircraft's aerodynamic characteristics is selected from multiple cross-sectional two-dimensional ice types of a certain component as the benchmark for subsequent ice type conversion.

[0012] Furthermore, from multiple cross-sectional two-dimensional icing patterns of a certain component, the icing pattern with the greatest impact on the aircraft's aerodynamic characteristics is selected as the benchmark for subsequent icing pattern conversion, including:

[0013] The most prominent ice corner feature of each ice profile is selected. This most prominent ice corner feature is the ice corner feature with the maximum projection height in its own ice profile.

[0014] A new profile is formed by aligning the leading edge of all the more obvious ice corner features with the chord line. The most obvious ice corner feature is selected on this profile, and the ice type corresponding to the most obvious ice corner feature is the ice type with the greatest aerodynamic influence.

[0015] If the ice type with the greatest aerodynamic impact cannot be selected, a two-dimensional ice type aerodynamic impact comparison calculation is carried out to determine the ice type with the greatest impact.

[0016] For ice types with obvious ice corner characteristics, select the ice type with the largest projected height of the icing ice corner in the lift direction and determine the ice type with the greatest aerodynamic influence. For cases where the ice corner characteristics are not obvious or the selection result is not unique, a two-dimensional ice type aerodynamic influence comparison calculation can be carried out to determine the ice type with the greatest influence.

[0017] Furthermore, based on aerodynamic similarity, the selected ice shapes are simplified, including:

[0018] From the coordinate points of the baseline profile, select the feature coordinate points that reflect the extreme shape and characteristic shape, as well as the contour coordinate points between a small number of feature points, and ignore the coordinate points of the shape details in the non-extreme area. Use spline curves to draw a simplified ice pattern to smooth the local pits and rough shape of the original ice pattern and meet the requirements of aircraft simulation ice pattern manufacturing.

[0019] An aerodynamic impact assessment is conducted before and after the simplification of the two-dimensional ice model. The feasibility of ice model simplification is determined based on the principle of equivalent aerodynamic forces. If it is not feasible, the coordinate points of some non-limit region shape details are retained to obtain a new simplified ice model. The aerodynamic impact assessment is conducted again until simplification is feasible.

[0020] Furthermore, the characteristic coordinate points reflecting the extreme shape and characteristic shape are the coordinate points of the upper / lower icing limit and the coordinate points of the upper / lower ice corner shape.

[0021] Furthermore, by employing methods such as ice-shape contour translation, bridging, surface filling, and extrapolation, the simplified ice shape is used to generate three-dimensional ice shapes with different airfoils, including:

[0022] The wingtip area is selected for ice shape simplification. The leading edge line of the tail is used as a guide line for translation and equal ice angle height adjustment to obtain the ice shape contours at both ends of the wing surface. The ice shape contours at both ends of the wing surface are bridged to obtain the three-dimensional ice shape of the entire wingspan.

[0023] Furthermore, by employing methods such as ice-shape contour translation, bridging, surface filling, and extrapolation, the simplified ice shape is used to generate three-dimensional ice shapes with different airfoils, including:

[0024] For the wing, the wingtip and wing root areas are selected for ice shape simplification. Using feature lines such as the ice shape outlines at both ends, the icing limit line connecting the upper and lower wing surfaces, and the ice angle line connecting the upper and lower wing surfaces, the three-dimensional ice shape surface of the upper wing surface, the three-dimensional ice shape surface of the windward surface, and the three-dimensional ice shape surface of the lower wing surface are generated in blocks using the closed curve filling method. Then, the leading edge ice shape of the wing outside the ice shape outlines is generated by the extrapolation extension method.

[0025] Beneficial effects

[0026] The three-dimensional ice profile generated by this method is simple, easy to process, and has realistic aerodynamic effects, and can be applied to the study and verification of the aerodynamic effects of aircraft icing. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of ice shape screening from the same measurement profile;

[0028] Figure 2 This is a schematic diagram of ice shape screening using the same component but different measurement profiles.

[0029] Figure 3 This is a simplified diagram of an ice shape;

[0030] Figure 4 This is a schematic diagram of the three-dimensional ice-shaped transformation of the tail fin surface;

[0031] Figure 5 This is a schematic diagram of the three-dimensional ice-shaped transformation of the wing surface. Detailed Implementation

[0032] This invention proposes a method for converting two-dimensional icing patterns of aircraft wings into three-dimensional icing patterns. The method involves selecting the icing pattern with the greatest aerodynamic influence from profile icing patterns obtained from icing wind tunnel tests. Based on aerodynamic similarity, the selected icing pattern is simplified. Then, through methods such as icing pattern contour translation, bridging, surface filling, and extrapolation extension, three-dimensional icing patterns for different wing surfaces are generated. This method includes the following steps:

[0033] (1) Ice type screening. Select the ice type with the greatest impact on the aerodynamic characteristics of the aircraft from multiple cross-sectional two-dimensional ice types of a certain component as the benchmark for subsequent ice type conversion: For ice types with obvious ice corner characteristics, the ice type with the largest projected height of the icing ice corner in the lift direction can be selected and the ice type with the greatest aerodynamic impact can be determined. For cases where the ice corner characteristics are not obvious or the selection result is not unique, a two-dimensional ice type aerodynamic impact comparison calculation can be carried out to determine the ice type with the greatest impact.

[0034] (2) Ice Pattern Simplification. From the coordinate points representing the original ice pattern outline, characteristic coordinate points reflecting the limiting shape and feature shape (upper / lower icing limit, upper / lower ice corner shape) and a small number of contour coordinate points between characteristic points are selected. Coordinate points of non-limiting area shape details are ignored. Spline curves are used to draw the simplified ice pattern to smooth the local pits and rough shape of the original ice pattern and meet the requirements of aircraft simulation ice pattern manufacturing. A two-dimensional aerodynamic impact assessment before and after ice pattern simplification is carried out, and the feasibility of ice pattern simplification is determined based on the principle of equivalent aerodynamic forces.

[0035] (3) Three-dimensional ice pattern conversion of the tail fin surface. The three-dimensional ice pattern conversion of the tail fin surface was obtained using the isosectional stretching method. The two-dimensional ice pattern of the wingtip area was selected after screening and simplification. The wingtip leading edge line was used as the guide line for translation and equal ice angle height adjustment to obtain the ice pattern contours at both ends of the fin surface. The ice pattern contours at both ends of the fin surface were bridged to obtain the three-dimensional ice pattern of the entire wingspan. Because the water droplet collection rate at the wingtip is higher than that at the wing root, the icing at the wingtip is more severe than that at the wing root. The ice pattern effect of the three-dimensional conversion using the ice pattern at the wingtip area is more severe. However, due to the small tail fin span, the deviation of this treatment method is acceptable.

[0036] (4) Three-dimensional ice pattern conversion of wing surface. The three-dimensional ice pattern conversion of wing surface is obtained by interpolation of different ice pattern profiles. The two-dimensional ice patterns of the wingtip and wing root are selected and simplified. The three-dimensional ice pattern surfaces of the upper wing surface, the windward surface, and the lower wing surface are generated in blocks by using the ice pattern profile lines at both ends, the icing limit line connecting the upper and lower wing surfaces, and the ice angle line connecting the upper and lower wing surfaces. The leading edge ice pattern of the wing outside the ice pattern profile lines is generated by using the closed curve filling method.

[0037] Example 1

[0038] This invention proposes a method for converting two-dimensional icing patterns of aircraft wings into three-dimensional icing patterns. Based on multiple known two-dimensional icing pattern profiles of aircraft wings, the method generates a full-span three-dimensional icing pattern through icing pattern selection, simplification, and three-dimensional icing pattern conversion. The specific implementation steps of this method are as follows:

[0039] Step 1: Place two-dimensional ice patterns of the same type and measurement profile of a test specimen together, aligned with the airfoil contours. Compare the projected height of the ice angle in the lift direction of each ice pattern, and select the ice pattern with the largest projected height as the selected ice pattern for that measurement profile. Figure 1 As shown; the selected ice type for other measurement profiles is determined using the same method; the selected ice types for each profile are placed together with the leading edge point and chord line aligned, and the projected height of the ice angle in the lift direction of each ice type is compared. The ice type with the largest projected height is selected as the selected ice type for this measurement component, such as... Figure 2 As shown.

[0040] Step 2: Simplify the ice pattern selected in Step 1. Use spline curve plotting to select characteristic coordinate points reflecting the extreme and characteristic shapes (upper / lower icing limits, upper / lower ice corner shapes) and contour coordinate points between a few characteristic points, ignoring coordinate points of non-extreme area shape details to form a simplified ice pattern, such as... Figure 3 As shown, aerodynamic calculations were performed on the airfoil plus the original ice shape / simplified ice shape. The appropriate simplified ice shape was determined based on the equivalence of aerodynamic forces before and after the simplification.

[0041] Step 3: For wings with a small span, such as the tail wing, mark the upper ice angle extreme point P0 on the simplified ice shape contour line L0 determined in Step 2. Using the leading edge line of the wing as a guide line, translate the ice shape contour line L0 and the ice angle extreme point P0 to both ends of the icing area on the wing surface, and make minor adjustments to the wing surface chord direction so that the height of the ice angle extreme points P1 and P2 at both ends from the wing surface is the same as P0, forming ice shapes L1 and L2 at both ends of the wing surface. Use a bridging method to generate a three-dimensional ice shape between L1 and L2, and process the gap and intersection between the three-dimensional ice shape and the wing surface through extrapolation extension and shearing. Figure 4 As shown.

[0042] Step 4: For wings with a large span, such as aircraft wings, determine the simplified ice patterns L1 and L2 at the wingtip and wing root respectively, as in Step 2. Based on the icing limit points of the upper and lower wing surfaces and the maximum thickness points of the upper and lower ice corners of ice patterns L1 and L2, draw lines connecting the icing limit points of the upper wing surface (L3), the lower wing surface (L4), the upper ice corner (L5), and the lower ice corner (L6). Select ice patterns L1 and L2 and the connecting lines L3 and L5 and use the closed curve filling method to generate a three-dimensional ice pattern surface for the upper wing surface. Select ice patterns L1 and L2 and the connecting lines L5 and L6 and use the closed curve filling method to generate a three-dimensional ice pattern surface for the windward side. Select ice patterns L1 and L2 and the connecting lines L6 and L4 and use the closed curve filling method to generate a three-dimensional ice pattern surface for the lower wing surface. Then, use the extrapolation extension method to extrapolate the three surfaces obtained above to both ends of the wing surface to obtain the three-dimensional ice pattern of the entire leading edge of the wing. Figure 5 As shown.

Claims

1. A method for converting a two-dimensional icing pattern on an aircraft wing surface into a three-dimensional icing pattern, characterized in that, include: The ice type with the greatest aerodynamic influence was selected from the ice profiles obtained from the ice wind tunnel test. The selected ice shapes are simplified based on aerodynamic similarity; By using methods such as ice shape contour translation, bridging or surface filling, and extrapolation extension, the simplified ice shape is used to generate three-dimensional ice shapes with different airfoils; The ice shape simplification based on aerodynamic similarity includes: From the coordinate points of the baseline profile, select the feature coordinate points that reflect the extreme shape and characteristic shape, as well as the contour coordinate points between a small number of feature points, and ignore the coordinate points of the shape details in the non-extreme area. Use spline curves to draw a simplified ice pattern to smooth the local pits and rough shape of the original ice pattern and meet the requirements of aircraft simulation ice pattern manufacturing. An aerodynamic impact assessment is conducted before and after the simplification of the two-dimensional ice model. The feasibility of ice model simplification is determined based on the principle of equivalent aerodynamic forces. If it is not feasible, the coordinate points of some non-limit region shape details are retained to obtain a new simplified ice model. The aerodynamic impact assessment is conducted again until simplification is feasible. The method of generating three-dimensional ice shapes with different airfoils from the simplified ice shape through ice shape contour translation, bridging or surface filling, and extrapolation extension includes: For the tail fin, the ice shape is simplified by selecting the wingtip area. The leading edge line of the tail fin is used as the guide line for translation and equal ice angle height adjustment to obtain the ice shape contours at both ends of the wing surface. The ice shape contours at both ends of the wing surface are bridged to obtain the three-dimensional ice shape of the entire wingspan. For the wing, the wingtip and wing root areas are selected for ice shape simplification. Using the ice shape outlines at both ends, the icing limit line connecting the upper and lower wing surfaces, and the ice angle line connecting the upper and lower wing surfaces as feature lines, the three-dimensional ice shape surface of the upper wing surface, the three-dimensional ice shape surface of the windward surface, and the three-dimensional ice shape surface of the lower wing surface are generated in blocks by using the closed curve filling method. Then, the leading edge ice shape of the wing outside the ice shape outlines is generated by using the extrapolation extension method.

2. The method according to claim 1, characterized in that, The ice types with the greatest aerodynamic influence were selected from the ice profiles obtained from the ice wind tunnel tests, including: The ice type with the greatest impact on the aircraft's aerodynamic characteristics is selected from multiple cross-sectional two-dimensional ice types of a certain component as the benchmark for subsequent ice type conversion.

3. The method according to claim 2, characterized in that, From multiple cross-sectional two-dimensional icing patterns of a certain component, the icing pattern with the greatest impact on the aircraft's aerodynamic characteristics is selected as the benchmark for subsequent icing pattern conversion, including: The most prominent ice corner feature of each ice profile is selected. This most prominent ice corner feature is the ice corner feature with the maximum projection height in its own ice profile. A new profile is formed by aligning the leading edge of all the more obvious ice corner features with the chord line. The most obvious ice corner feature is selected on this profile, and the ice type corresponding to the most obvious ice corner feature is the ice type with the greatest aerodynamic influence. If the ice type with the greatest aerodynamic impact cannot be selected, a two-dimensional ice type aerodynamic impact comparison calculation is carried out to determine the ice type with the greatest impact. For ice types with obvious ice corner characteristics, select the ice type with the largest projected height of the icing ice corner in the lift direction and determine the ice type with the greatest aerodynamic influence. For cases where the ice corner characteristics are not obvious or the selection result is not unique, a two-dimensional ice type aerodynamic influence comparison calculation can be carried out to determine the ice type with the greatest influence.

4. The method according to claim 1, characterized in that, The characteristic coordinate points reflecting the extreme shape and characteristic shape are the coordinate points of the upper / lower icing limit and the coordinate points of the upper / lower ice corner shape.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1-4.

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