A simulation calculation method and device for de-icing efficiency of an airbag-type de-icing system for airfoils

Abstract

This application provides a method and apparatus for simulating and calculating the de-icing efficiency of an airbag-type de-icing system for an airfoil, comprising: Step 1: Defining the airfoil shape characteristics and airbag distribution, and completing the flow field division; Step 2: Using the two-dimensional shape description of the airfoil after flow field division, calculating the water droplet trajectory, and obtaining the local water droplet collection coefficient at each point in the leading edge protection zone of the airfoil; Step 3: Determining the icing cycle and generating the icing ice pattern based on the local water droplet collection coefficient, the initial value of the flow field variables, and the water droplet state value; Step 4: Inputting the actual conditions of the airbag and calculating the stress values ​​at each stage of airbag expansion; Step 5: Measuring the surface adhesion force F of ice on the airbag surface during the airbag de-icing process. τ Step 6: Based on the surface adhesion force F τ Step 7: Based on the ice shedding criteria, compare and analyze the effective de-icing area of ​​the entire protection zone when the airbag is working, and calculate the de-icing efficiency.

Description

Technical Field

[0001] This invention relates to the field of anti-icing system testing and evaluation, specifically to a method and apparatus for simulating and calculating the de-icing efficiency of an airbag-type de-icing system for aircraft wings. Background Technology

[0002] Aircraft icing is a phenomenon where supercooled water droplets in the atmosphere collide with and accumulate on the aircraft's surface when the aircraft encounters an icy environment during flight. Besides increasing the weight of components, icing on the aircraft surface alters the airflow around the surface, impairs aerodynamic performance, and reduces flight performance and quality. Therefore, icing is considered one of the key environmental factors inducing flight loss of control. Data shows that between 1978 and 2010, catastrophic accidents caused by icing accounted for 14.3% of all flight accidents globally. Among these, the aircraft wing is one of the most critical aircraft components affected by icing. When a thin layer of ice, as thin as sandpaper, condenses on the wing surface, it can lead to a lift loss of up to 30% and a drag increase of 40%, seriously threatening flight safety.

[0003] Currently, wing de-icing systems can be commonly classified into three categories: thermal anti-icing, electrothermal anti-icing, and airbag de-icing. Airbag de-icing systems involve installing airbags on the aircraft's protective outer surface. Periodically inflating and deflating these airbags causes physical deformation, thus removing ice from the protective surface. However, considering that airbags rely on expansion and contraction forces for de-icing, they cannot completely remove ice. Aircraft may fly with ice in icing clouds, and given the complex weather conditions during icing, the risk of natural icing verification flight tests using airbag de-icing is high. Furthermore, compared to thermal and electrothermal anti-icing systems, airbag de-icing lacks standardized metrics for de-icing effectiveness and has been less frequently verified through natural icing, resulting in insufficient past experience. Because research on airbag de-icing methods is currently limited, it is impossible to comprehensively evaluate its de-icing performance during flight test design and implementation. Therefore, there is an urgent need to conduct research on simulation calculation methods for the de-icing efficiency of wing airbag de-icing systems. Summary of the Invention

[0004] This application proposes a simulation calculation method and device for the de-icing efficiency of an airbag-type de-icing system for aircraft wings. It can calculate the effective de-icing area of ​​the airbag-type de-icing system for aircraft wings at various icing states, quantitatively characterize the de-icing effect of the airbag-type de-icing system, and provide data reference for the evaluation of the de-icing capability of the wing de-icing system.

[0005] The technical solution of the present invention:

[0006] In a first aspect, this application provides a method for simulating and calculating the de-icing efficiency of an airbag-type de-icing system for airfoils, the method comprising:

[0007] Step 1: Define the wing shape characteristics and wing airbag distribution to complete the flow field division;

[0008] Step 2: Using the two-dimensional shape description of the wing after the flow field division, establish the equations for mass conservation, momentum conservation, and energy conservation, calculate the water droplet trajectory, and obtain the local water droplet collection coefficient at each point in the leading edge protection area of ​​the wing;

[0009] Step 3: Determine the icing period based on the local droplet collection coefficient, the initial value of the flow field variables, and the droplet state value. Select the Messier model to calculate the icing rate, obtain the icing thickness at each point in the leading edge protection zone of the wing, and generate the icing pattern.

[0010] Step 4: Input the actual conditions of the airbag and calculate the stress values ​​at each stage of airbag inflation;

[0011] Step 5: Based on the characteristics of the airbag and the ice formation pattern, the ice adhesion force is measured using the pull-out method to measure the surface adhesion force of ice on the airbag surface during the airbag de-icing process. ;

[0012] Step 6: Based on surface adhesion Establish ice shedding criteria for each point in the wing leading edge protection zone during airbag expansion to determine whether ice detaches;

[0013] Step 7: Under given air supply conditions, based on the ice shedding criterion, compare and analyze the effective de-icing area of ​​the entire protected area when the airbag is working, and calculate the de-icing efficiency.

[0014] Furthermore, step 1 includes:

[0015] Step 11: Measure the wing shape to obtain wing shape characteristics and airbag properties;

[0016] Step 12: Convert the wing shape features into a two-dimensional wing shape description. ;

[0017] Step 13: In the description of the two-dimensional shape of the wing Above, the starting position of the upper leading edge protection and the ending position of the lower leading edge protection are set;

[0018] Step 14: Based on the two-dimensional shape description of the wing, use the mesh generation method to calculate the region mesh division and complete the flow field division.

[0019] Furthermore, the airbag characteristics include airbag material, distribution range, number of airbag segments, width of a single airbag manifold, thickness of airbag material, and width of the frame;

[0020] The wing shape features include the wing chord, leading edge, trailing edge, thickness, and leading edge radius.

[0021] Furthermore, step 4 includes:

[0022] Step 41: Using the actual conditions of the airbag, simplify the single-segment airbag manifold to obtain a single-segment airbag manifold model;

[0023] Step 42: For the single-segment airbag manifold model, determine the airbag state variables;

[0024] Step 43: Based on the airbag state parameters, simulate the stress changes during the airbag inflation process of the single-segment airbag manifold model.

[0025] Step 44: Calculate the surface normal deformation and stress value at each point of a single air bladder under different inflation states.

[0026] Furthermore, the airbag state parameters include airbag tube width, airbag material thickness, airbag material elastic modulus, airbag material Poisson's ratio, and airbag supply pressure.

[0027] Furthermore, the ice shedding criterion is as follows:

[0028] When the airbag is fully inflated, At that time, the ice at that point will break off;

[0029] when If the ice does not break off at that point, then the ice will not fall off.

[0030] in, The ice adhesion force value measured at the location of this single airbag segment; This represents the stress value at this single airbag location.

[0031] Furthermore, step 7 includes:

[0032] Step 71: Using the ice shedding criterion, for the first... The airbag segment is judged to obtain the first... Effective de-icing length of segment airbag ;

[0033] Step 72: Based on the total number of airbag segments and effective de-icing length Using the formula

[0034] Calculate the effective de-icing area ;

[0035] Step 73: De-icing area Divide by the protected area of ​​the wing leading edge protection zone to obtain the de-icing efficiency.

[0036] Secondly, this application provides a simulation calculation device for the de-icing efficiency of an airbag-type de-icing system, the device being used to implement the above-mentioned simulation calculation method for the de-icing efficiency of an airbag-type de-icing system.

[0037] In summary, this application provides a simulation calculation method and apparatus for the de-icing efficiency of an airbag-type de-icing system for aircraft wings. Through technological advancements in the physical properties, icing characteristics, and ice shedding mechanisms of the airbag, and based on the characteristics of airbag-type de-icing systems, this application addresses the high risks and lack of prior experience associated with natural icing during test flights of airbag-type de-icing systems. Numerical calculations are used to simulate the airbag expansion process and icing. Laboratory experiments are conducted to study the adhesion characteristics of icing on the airbag, and a reasonable ice shedding criterion is selected. Finally, a quantitative evaluation of the de-icing effect of the system is calculated, providing data support for the functional performance evaluation and system design optimization of aircraft wing airbag-type de-icing systems, effectively enhancing the value of experimental data. Attached Figure Description

[0038] Figure 1 A flowchart illustrating the simulation calculation method for the de-icing efficiency of an airbag-type de-icing system for an airfoil provided in this application. Detailed Implementation

[0039] like Figure 1 As shown, a simulation calculation method for the de-icing efficiency of an airbag-type de-icing system for airfoils is proposed, applicable to the performance evaluation of airbag-type de-icing systems. The implementation method is illustrated using a two-dimensional airfoil. The method includes the following steps:

[0040] Step 1: Define the wing shape characteristics and wing airbag distribution to complete the flow field division;

[0041] Specifically, step 1 includes:

[0042] Step 11: Measure the wing shape to obtain wing shape characteristics and airbag properties;

[0043] Step 12: Convert the wing shape features into a two-dimensional wing shape description. ;

[0044] Step 13: In the description of the two-dimensional shape of the wing Mark the starting position of the upper leading edge protection and the ending position of the lower leading edge protection on the wing.

[0045] Step 14: Based on the two-dimensional shape description of the wing, use the mesh generation method to calculate the region mesh division and complete the flow field division.

[0046] The airbag characteristics include airbag material, distribution range, number of airbag segments, width of a single airbag manifold, airbag material thickness, and frame width. The wing shape features include wing chord, leading edge, trailing edge, thickness, and leading edge radius.

[0047] For example, the airbag material is rubber, distributed from the starting position of the upper front edge protection to the ending position of the lower front edge protection, with 15 airbag segments, a single airbag manifold width of 25mm, an airbag material thickness of 12mm, and a frame width of 5mm.

[0048] Step 2: Using the two-dimensional shape description of the wing after the flow field division, establish equations such as mass conservation, momentum conservation, and energy conservation, calculate the water droplet trajectory, and obtain the local water droplet collection coefficient at each point in the leading edge protection area of ​​the wing;

[0049] The leading edge protection zone of the wing extends from the starting position of the upper leading edge protection to the ending position of the lower leading edge protection.

[0050] Step 3: Determine the icing period based on the local droplet collection coefficient, the initial value of the flow field variables, and the droplet state value. Select the Messier model to calculate the icing rate, obtain the icing thickness at each point in the leading edge protection zone of the wing, and generate the icing pattern.

[0051] Step 4: Input the actual conditions of the airbag and calculate the stress values ​​at each stage of airbag inflation;

[0052] Specifically, step 4 includes:

[0053] Step 41: Using the actual conditions of the airbag, simplify the single-segment airbag manifold to obtain a single-segment airbag manifold model;

[0054] It should be noted that the analysis of a single-segment airbag manifold is as follows:

[0055] 1) When not in operation, the airbag is a flat plate, and its curvature when attached to the wing surface is ignored;

[0056] 2) The de-icing process of the airbag is mainly studied in terms of the normal deformation of the airbag during expansion, while ignoring its tangential and spanwise deformation;

[0057] 3) The material properties of the airbag do not change during the inflation process.

[0058] Step 42: For the single-segment airbag manifold model, determine the airbag state variables;

[0059] The airbag state parameters include airbag tube width, airbag material thickness, airbag material elastic modulus, airbag material Poisson's ratio, and airbag supply pressure.

[0060] For example, the manifold width is 25mm, the airbag material thickness is 12mm, the airbag material elastic modulus is 3.8MPa, the material Poisson's ratio is 0.49, and the airbag supply pressure is 0.8Bar.

[0061] Step 43: Based on the airbag state parameters, simulate the stress changes during the airbag inflation process of the single-segment airbag manifold model.

[0062] Specifically, the airbag is simulated using Ansys Mechanical, a general-purpose mechanical analysis software, during the airbag inflation process. This includes steps such as material setting, mesh generation, constraint verification, load input, and calculation execution.

[0063] Step 44: Calculate the surface normal deformation and stress value at each point of a single air bladder under different inflation states.

[0064] Step 5: Based on the characteristics of the airbag and the ice formation pattern, the ice adhesion force is measured using the pull-out method to measure the surface adhesion force of ice on the airbag surface during the airbag de-icing process. .

[0065] Specifically, the pull-off test is performed in accordance with the national standard "Pull-off Adhesion Test of Paints and Varnishes" (Standard No.: GB_T5210-2006).

[0066] Step 6: Based on surface adhesion Establish ice shedding criteria for each point in the wing leading edge protection zone during airbag expansion to determine whether ice falls off.

[0067] Specifically, the ice shedding criterion is as follows:

[0068] When the airbag is fully inflated, At that time, the ice at that point will break off;

[0069] when If the ice does not break off at that point, then the ice will not fall off.

[0070] in, The ice adhesion force value measured at the location of this single airbag segment; This represents the stress value at this single airbag location.

[0071] Step 7: Under given air supply conditions, based on the ice shedding criterion, compare and analyze the effective de-icing area of ​​the entire protected area when the airbag is working, and calculate the de-icing efficiency.

[0072] Specifically, step 7 includes:

[0073] Step 71: Using the ice shedding criterion, for the first... The airbag segment is judged to obtain the first... Effective de-icing length of segment airbag ;

[0074] Step 72: Based on the total number of airbag segments and effective de-icing length Using the formula

[0075] Calculate the effective de-icing area ;

[0076] Step 73: De-icing area Divide by the protected area of ​​the wing leading edge protection zone to obtain the de-icing efficiency.

[0077] The effective de-icing area of ​​the wing leading edge protection zone during airbag operation is defined as the area of ​​ice that falls off from the entire protection zone after the airbag completes one expansion-inflation-de-icing and full contraction cycle.

[0078] In summary, this application provides a simulation calculation method and apparatus for the de-icing efficiency of an airbag-type de-icing system for aircraft wings. Through technological advancements in the physical properties, icing characteristics, and ice shedding mechanisms of the airbag, and based on the characteristics of airbag-type de-icing systems, this application addresses the high risks and lack of prior experience associated with natural icing during test flights of airbag-type de-icing systems. Numerical calculations are used to simulate the airbag expansion process and icing. Laboratory experiments are conducted to study the adhesion characteristics of icing on the airbag, and a reasonable ice shedding criterion is selected. Finally, a quantitative evaluation of the de-icing effect of the system is calculated, providing data support for the functional performance evaluation and system design optimization of aircraft wing airbag-type de-icing systems, effectively enhancing the value of experimental data.

Claims

1. A simulation calculation method for the de-icing efficiency of an airbag-type de-icing system for airfoils, characterized in that, The method includes: Step 1: Define the wing shape characteristics and wing airbag distribution to complete the flow field division; Step 2: Using the two-dimensional shape description of the wing after the flow field division, establish the equations for mass conservation, momentum conservation, and energy conservation, calculate the water droplet trajectory, and obtain the local water droplet collection coefficient at each point in the leading edge protection area of ​​the wing; Step 3: Determine the icing period based on the local droplet collection coefficient, the initial value of the flow field variables, and the droplet state value. Select the Messier model to calculate the icing rate, obtain the icing thickness at each point in the leading edge protection zone of the wing, and generate the icing pattern. Step 4: Input the actual conditions of the airbag and calculate the stress values ​​at each stage of airbag inflation; Step 5: Based on the characteristics of the airbag and the ice formation pattern, the ice adhesion force is measured using the pull-out method to measure the surface adhesion force of ice on the airbag surface during the airbag de-icing process. ; Step 6: Based on surface adhesion Establish ice shedding criteria for each point in the wing leading edge protection zone during airbag expansion to determine whether ice detaches; Step 7: Under given air supply conditions, based on the ice shedding criterion, compare and analyze the effective de-icing area of ​​the entire protected area when the airbag is working, and calculate the de-icing efficiency.

2. The method according to claim 1, characterized in that, Step 1 includes: Step 11: Measure the wing shape to obtain wing shape characteristics and airbag properties; Step 12: Convert the wing shape features into a two-dimensional wing shape description. ; Step 13: In the description of the two-dimensional shape of the wing Above, the starting position of the upper leading edge protection and the ending position of the lower leading edge protection are set; Step 14: Based on the two-dimensional shape description of the wing, use the mesh generation method to calculate the region mesh division and complete the flow field division.

3. The method according to claim 2, characterized in that, The airbag characteristics include airbag material, distribution range, number of airbag segments, width of a single airbag manifold, thickness of airbag material, and width of the frame; The wing shape features include the wing chord, leading edge, trailing edge, thickness, and leading edge radius.

4. The method according to claim 1, characterized in that, Step 4 includes: Step 41: Using the actual conditions of the airbag, simplify the single-segment airbag manifold to obtain a single-segment airbag manifold model; Step 42: For the single-segment airbag manifold model, determine the airbag state variables; Step 43: Based on the airbag state parameters, simulate the stress changes during the airbag inflation process of the single-segment airbag manifold model. Step 44: Calculate the surface normal deformation and stress value at each point of a single air bladder under different inflation states.

5. The method according to claim 4, characterized in that, The airbag state parameters include airbag tube width, airbag material thickness, airbag material elastic modulus, airbag material Poisson's ratio, and airbag supply pressure.

6. The method according to claim 4, characterized in that, The ice shedding criterion is as follows: When the airbag is fully inflated, At that time, the ice at that point will break off; when If the ice does not break off at that point, then the ice will not fall off. in, The ice adhesion force value measured at the location of this single airbag segment; This represents the stress value at the point where the airbag is located.

7. The method according to claim 1, characterized in that, Step 7 includes: Step 71: Using the ice shedding criterion, for the first... The airbag segment is judged to obtain the first... Effective de-icing length of segment airbag ; Step 72: Based on the total number of airbag segments and effective de-icing length Using the formula Calculate the effective de-icing area ; Step 73: De-icing area Divide by the protected area of ​​the wing leading edge protection zone to obtain the de-icing efficiency.

8. A simulation and calculation device for the de-icing efficiency of an airbag-type de-icing system for aircraft wings, characterized in that, The device is used to implement the simulation calculation method for the de-icing efficiency of the wing airbag de-icing system as described in claim 1.

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