Simulation calculation method and device for deicing efficiency of wing airbag type deicing system

Abstract

The invention provides a deicing efficiency simulation calculation method and device for a wing airbag type deicing system, and the method comprises the steps: 1, determining the appearance characteristics of a wing and the distribution of wing airbags, and completing the division of a flow field; 2, calculating a water drop track by using the wing two-dimensional shape description after flow field division to obtain a local water drop collection coefficient of each point position of the wing leading edge protection area; 3, according to the local water drop collection coefficient, the flow field variable initial value and the water drop state value, an icing period is determined, and an icing ice type is generated; 4, inputting actual conditions of the air bag, and calculating stress values of the air bag in each expansion stage; 5, measuring the surface adhesive force F [tau] of ice on the surface of the air bag in the deicing process of the air bag; step 6, according to the surface adhesive force F [tau], establishing an ice falling criterion whether ice falls off or not in each point position of the wing leading edge protection area in the airbag expansion process; and step 7, according to an ice shedding criterion, contrastively analyzing and giving an effective deicing area of the whole protection area when the air bag works, and calculating and giving the deicing efficiency.

Description

Technical Field

[0001] The invention relates to the field of test and evaluation of anti-icing systems, and in particular to a method and device for simulating and calculating the deicing efficiency of a wing airbag deicing system. Background Art

[0002] Aircraft icing is a phenomenon in which supercooled water droplets in the atmosphere hit the surface of the aircraft and accumulate into ice when the aircraft encounters an icy environment during flight. When the surface of the aircraft is frozen, in addition to increasing the weight of the components, it will also change the flow field around the surface of the aircraft, destroy the aerodynamic performance, and reduce the flight performance and flight quality of the aircraft. Therefore, icing is considered to be one of the key environmental factors that induce flight loss of control. Data show that between 1978 and 2010, catastrophic accidents caused by icing accounted for 14.3% of total flight accidents worldwide. Among them, the aircraft wing is one of the key aircraft components most affected by icing. When sandpaper-thin ice condenses on the surface of the wing, it can cause up to 30% lift loss and 40% increase in drag, seriously threatening flight safety.

[0003] Wing anti-icing systems are currently divided into three categories: hot air anti-icing, electric heating anti-icing, and airbag deicing. The airbag deicing system is a deicing system that installs airbags on the outer surface of the aircraft protection, and physically deforms the airbags by periodically inflating and deflating them, thereby removing ice from the protective surface. Considering that airbags rely on expansion and contraction to remove ice completely, aircraft will fly with ice in icing cloud areas, and the icing weather is complex, so the risk of natural icing verification flight test for airbag deicing is high; and compared with hot air anti-icing and electric heating anti-icing systems, airbag deicing lacks a measurement standard for deicing effects, and rarely conducts natural icing verification, and past experience is insufficient. Because there is little research on airbag deicing methods at present, it is impossible to comprehensively evaluate its deicing performance during the test flight design and test implementation process. Therefore, there is an urgent need to carry out research on the simulation calculation method of deicing efficiency of wing airbag deicing systems. Summary of the invention

[0004] The present application proposes a method and device for simulating and calculating the de-icing efficiency of a wing airbag de-icing system, which can calculate the effective de-icing area of ​​the aircraft wing airbag de-icing system under various icing state points, quantitatively characterize the de-icing effect of the airbag de-icing system, and provide data reference for evaluating the de-icing capability of the wing de-icing system.

[0005] The technical solution of the present invention:

[0006] In a first aspect, the present application provides a method for simulating and calculating deicing efficiency of a wing airbag deicing system, the method comprising:

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

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

[0009] Among them, the wing leading edge protection area is from the leading edge upper protection starting position to the leading edge lower protection ending position;

[0010] Step 3: According to the local droplet collection coefficient, the initial value of the flow field variable and the droplet state value, the icing period is determined, the Messinger model is selected to calculate the icing rate, the icing thickness at each point in the wing leading edge protection area is obtained, and the icing ice type is generated;

[0011] Step 4: Input the actual conditions of the airbag and calculate the stress values ​​at each stage of airbag expansion;

[0012] Step 5: According to the characteristics of the airbag and the ice type, the ice adhesion force is measured by pulling apart the airbag to measure the surface adhesion force F of the ice on the airbag surface during the airbag deicing process. τ ;

[0013] Step 6: According to the surface adhesion F τ , establish ice shedding criteria for determining whether ice will fall off at each point in the wing leading edge protection zone during the airbag inflation process;

[0014] Step 7: Under given air supply conditions, based on the ice shedding criteria, comparative analysis is performed to determine the effective deicing area of ​​the entire protection zone when the airbag is operating, and the deicing efficiency is calculated.

[0015] Furthermore, step 1 includes:

[0016] Step 11: Measure the wing shape to obtain the wing shape characteristics and airbag characteristics;

[0017] Step 12: converting the wing shape feature into a two-dimensional wing shape description (x, y);

[0018] Step 13: setting the starting position of the upper protection of the leading edge of the wing and the ending position of the lower protection of the leading edge of the wing on the two-dimensional shape description (x, y);

[0019] Step 14: Based on the two-dimensional shape description of the wing, use the grid generation method to calculate the regional grid division and complete the flow field division.

[0020] Further, the airbag characteristics include airbag material, distribution range, number of airbag segments, width of single-segment airbag manifold, thickness of airbag material, and width of frame;

[0021] The wing shape features include wing chord, leading edge, trailing edge, thickness, and leading edge radius.

[0022] Furthermore, step 4 includes:

[0023] Step 41: using the actual conditions of the airbag, simplifying the single-stage airbag manifold to obtain a single-stage airbag manifold model;

[0024] Step 42: determining the airbag state quantity for the single-stage airbag manifold model;

[0025] Step 43: According to the airbag state quantity, simulate the stress change of the single-stage airbag manifold model during the airbag expansion process;

[0026] Step 44: Calculate and give the surface normal deformation and stress value of each point of the single-segment airbag under different expansion states of the airbag.

[0027] Furthermore, the airbag state quantity includes the airbag tube width, the airbag material thickness, the airbag material elastic modulus, the airbag material Poisson's ratio, and the air bag air supply pressure.

[0028] Furthermore, the ice shedding criterion is:

[0029] When the airbag is fully inflated, τ <F σ When F τ ≥F σ When , the ice at this point will not fall off;

[0030] Among them, F τ F is the ice adhesion value measured at the single-stage airbag point; σ is the stress value of the single-section airbag point.

[0031] Furthermore, step 7 includes:

[0032] Step 71: Using the ice shedding criterion, determine the i-th airbag and obtain the effective deicing length L of the i-th airbag i ;

[0033] Step 72: According to the total number of airbag segments I and the effective deicing length L i , using the formula Calculate the effective deicing area S0;

[0034] Step 73: Divide the effective deicing area S0 by the protection area of ​​the wing leading edge protection zone to obtain the deicing efficiency.

[0035] In a second aspect, the present application provides a device for simulating and calculating the deicing efficiency of a wing airbag deicing system, characterized in that the device is used to implement the above-mentioned method for simulating and calculating the deicing efficiency of a wing airbag deicing system.

[0036] In summary, the present application provides a method and device for simulating and calculating the de-icing efficiency of a wing airbag de-icing system. Based on the characteristics of the airbag de-icing system, the application makes technical developments in the physical properties of the airbag, the ice accumulation characteristics of the airbag, and the ice accretion and shedding mechanism. In view of the high risk of natural icing test flights of the airbag de-icing system and the lack of past experience, the application uses numerical calculations to simulate the airbag inflation process and icing, and uses laboratory experiments to study the adhesion characteristics of ice accretion in the airbag. A reasonable ice layer loosening criterion is selected, and finally a quantitative evaluation representation of the de-icing effect of the de-icing system is calculated, which provides data support for the functional performance identification and system design optimization of the aircraft wing airbag de-icing system, and effectively improves the value of the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic flow chart of a method for simulating and calculating the de-icing efficiency of a wing airbag de-icing system provided in this application. DETAILED DESCRIPTION

[0038] like Figure 1 As shown, a simulation calculation method for deicing efficiency of a wing airbag deicing system is proposed, which is suitable for the performance evaluation of the airbag deicing system. The method implementation method is described using a two-dimensional wing. The method includes the following steps:

[0039] Step 1: Clarify the wing shape characteristics and wing airbag distribution, and complete the flow field division;

[0040] Specifically, step 1 includes:

[0041] Step 11: Measure the wing shape to obtain the wing shape characteristics and airbag characteristics;

[0042] Step 12: converting the wing shape feature into a two-dimensional wing shape description (x, y);

[0043] Step 13: Mark the starting position of the upper protection of the leading edge of the wing and the ending position of the lower protection of the leading edge on the two-dimensional shape description (x, y) of the wing;

[0044] Step 14: Based on the two-dimensional shape description of the wing, use the grid generation method to calculate the regional grid division and complete the flow field division.

[0045] The airbag characteristics include airbag material, distribution range, number of airbag sections, width of single-section airbag manifold, thickness of airbag material, width of frame, etc. The wing shape features include wing chord, leading edge, trailing edge, thickness, and leading edge radius.

[0046] For example, the airbag material is a rubber part, and the distribution range is from the starting position of the upper front edge protection to the ending position of the lower front edge protection. The number of airbag segments is 15, the width of a single-section airbag manifold is 25mm, the thickness of the airbag material is 12mm, and the frame width is 5mm.

[0047] Step 2: Using the two-dimensional shape description of the wing after flow field division, establish equations such as conservation of mass, conservation of momentum, and conservation of energy, calculate the trajectory of water droplets, and obtain the local water droplet collection coefficient at each point in the wing leading edge protection area;

[0048] Among them, the leading edge protection area of ​​the wing is from the starting position of the upper leading edge protection to the ending position of the lower leading edge protection.

[0049] Step 3: According to the local droplet collection coefficient, the initial value of the flow field variable and the droplet state value, the icing period is determined, the Messinger model is selected to calculate the icing rate, the icing thickness at each point in the wing leading edge protection area is obtained, and the icing ice type is generated;

[0050] Step 4: Input the actual conditions of the airbag and calculate the stress values ​​at each stage of airbag expansion;

[0051] Specifically, step 4 includes:

[0052] Step 41: using the actual conditions of the airbag, simplifying the single-stage airbag manifold to obtain a single-stage airbag manifold model;

[0053] It should be noted that the analysis of the single-stage airbag manifold is as follows:

[0054] 1) The airbag in the non-working state is a flat plate, and its curvature on the wing surface is ignored;

[0055] 2) The deicing process of the airbag focuses on the normal deformation of the airbag expansion, ignoring its tangential and span deformations;

[0056] 3) The material properties of the airbag do not change during the inflation process.

[0057] Step 42: determining the airbag state quantity for the single-stage airbag manifold model;

[0058] The airbag state quantity includes the airbag tube width, the airbag material thickness, the airbag material elastic modulus, the airbag material Poisson's ratio, the airbag air supply pressure, etc.

[0059] For example, the manifold width is 25 mm, the airbag material thickness is 12 mm, the airbag material elastic modulus is 3.8 MPa, the material Poisson's ratio is 0.49, and the airbag air supply pressure is 0.8 Bar.

[0060] Step 43: According to the airbag state quantity, simulate the stress change of the single-stage airbag manifold model during the airbag expansion process;

[0061] Specifically, the airbag selected Ansys Mechanical general mechanical analysis software to simulate the stress change during the airbag inflation process, including material setting, mesh division, constraint confirmation, load input, calculation operation and other steps.

[0062] Step 44: Calculate and give the surface normal deformation and stress value of each point of the single-segment airbag under different expansion states of the airbag.

[0063] Step 5: According to the characteristics of the airbag and the ice type, the ice adhesion force is measured by pulling apart the airbag to measure the surface adhesion force F of the ice on the airbag surface during the airbag deicing process. τ .

[0064] Specifically, the pull-off test is performed in accordance with the national standard "Pull-off adhesion test for paints and varnishes" (standard number: GB_T5210-2006).

[0065] Step 6: According to the surface adhesion F τ , establish ice shedding criteria for determining whether ice will fall off at each point in the wing leading edge protection zone during the airbag inflation process;

[0066] Specifically, the ice shedding criterion is:

[0067] When the airbag is fully inflated, τ <F σ When F τ <F σ When , the ice at that point falls off;

[0068] Among them, F τ F is the ice adhesion value measured at the single-stage airbag point; σ is the stress value of the single-section airbag point.

[0069] Step 7: Under given air supply conditions, based on the ice shedding criteria, comparative analysis is performed to determine the effective deicing area of ​​the entire protection zone when the airbag is operating, and the deicing efficiency is calculated.

[0070] Specifically, step 7 includes:

[0071] Step 71: Using the ice shedding criterion, determine the i-th airbag and obtain the effective deicing length L of the i-th airbag i ;

[0072] Step 72: According to the total number of airbag segments I and the effective deicing length L i , using the formula Calculate the effective deicing area S0;

[0073] Step 73: Divide the effective deicing area S0 by the protection area of ​​the wing leading edge protection zone to obtain the deicing efficiency.

[0074] Among them, the effective de-icing area of ​​the wing leading edge protection zone when the airbag is working is defined as the area of ​​ice detachment in the entire protection zone after the airbag completes a cycle of expansion, inflation, de-icing and complete contraction.

[0075] In summary, the present application provides a method and device for simulating and calculating the de-icing efficiency of a wing airbag de-icing system. Based on the characteristics of the airbag de-icing system, the application makes technical developments in the physical properties of the airbag, the ice accumulation characteristics of the airbag, and the ice accretion and shedding mechanism. In view of the high risk of natural icing test flights of the airbag de-icing system and the lack of past experience, the application uses numerical calculations to simulate the airbag inflation process and icing, and uses laboratory experiments to study the adhesion characteristics of ice accretion in the airbag. A reasonable ice layer loosening criterion is selected, and finally a quantitative evaluation representation of the de-icing effect of the de-icing system is calculated, which provides data support for the functional performance identification and system design optimization of the aircraft wing airbag de-icing system, and effectively improves the value of the test data.

Claims

1. A simulation calculation method for deicing efficiency of a wing airbag deicing system, characterized in that: The method comprises: Step 1: Clarify the wing shape characteristics and wing airbag distribution, and complete the flow field division; Step 2: Using the two-dimensional shape description of the wing after flow field division, establish equations such as conservation of mass, conservation of momentum, and conservation of energy, calculate the trajectory of water droplets, and obtain the local water droplet collection coefficient at each point in the wing leading edge protection area; Step 3: According to the local droplet collection coefficient, the initial value of the flow field variable and the droplet state value, the icing period is determined, the Messinger model is selected to calculate the icing rate, the icing thickness at each point in the wing leading edge protection area is obtained, and the icing ice type is generated; Step 4: Input the actual conditions of the airbag and calculate the stress values ​​at each stage of airbag expansion; Step 5: According to the characteristics of the airbag and the ice type, the ice adhesion force is measured by pulling apart the airbag to measure the surface adhesion force F of the ice on the airbag surface during the airbag deicing process. τ ; Step 6: According to the surface adhesion F τ , establish ice shedding criteria for determining whether ice will fall off at each point in the wing leading edge protection zone during the airbag inflation process; Step 7: Under given air supply conditions, based on the ice shedding criteria, comparative analysis is performed to determine the effective deicing area of ​​the entire protection zone when the airbag is operating, and the deicing efficiency is calculated.

2. The method according to claim 1, characterized in that: Step 1 includes: Step 11: Measure the wing shape to obtain the wing shape characteristics and airbag characteristics; Step 12: converting the wing shape feature into a two-dimensional wing shape description (x, y); Step 13: setting the starting position of the upper protection of the leading edge of the wing and the ending position of the lower protection of the leading edge of the wing on the two-dimensional shape description (x, y); Step 14: Based on the two-dimensional shape description of the wing, use the grid generation method to calculate the regional grid 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 single-segment airbag manifold, thickness of airbag material, and width of frame; The wing shape features include 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, simplifying the single-stage airbag manifold to obtain a single-stage airbag manifold model; Step 42: determining the airbag state quantity for the single-stage airbag manifold model; Step 43: According to the airbag state quantity, simulate the stress change of the single-stage airbag manifold model during the airbag expansion process; Step 44: Calculate and give the surface normal deformation and stress value of each point of the single-segment airbag under different expansion states of the airbag.

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

6. The method according to claim 1, characterized in that The ice shedding criteria are: When the airbag is fully inflated, τ <F σ When F τ ≥F σ When , the ice at this point will not fall off; Among them, F τ F is the ice adhesion value measured at the single-stage airbag point; σ is the stress value of the single-section airbag point.

7. The method according to claim 1, characterized in that Step 7 includes: Step 71: Using the ice shedding criterion, determine the i-th airbag and obtain the effective deicing length L of the i-th airbag i ; Step 72: According to the total number of airbag segments I and the effective deicing length L i , using the formula Calculate the effective deicing area S0; Step 73: Divide the effective deicing area S0 by the protection area of ​​the wing leading edge protection zone to obtain the deicing efficiency.

8. A wing airbag deicing system deicing efficiency simulation calculation device, characterized in that: The device is used to implement the deicing efficiency simulation calculation method of the wing airbag deicing system described in claim 1.

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