Method and device for researching high-speed aerodynamic characteristics of airplane with simulated ice type

Abstract

The invention belongs to the field of aircraft aerodynamic design, and relates to a research method and device for high-speed aerodynamic characteristics of an aircraft with a simulated ice mold. The research method comprises the steps that numerical simulation and wind tunnel test methods are comprehensively adopted, and aircraft high-speed icing aerodynamic characteristic influence data are obtained by carrying out icing test condition screening, two-dimensional ice type screening, conversion from a two-dimensional ice type to a three-dimensional ice type and a high-speed wind tunnel test with a simulated ice type.

Description

Technical Field

[0001] The invention belongs to the field of aircraft aerodynamic design, and relates to a method and a device for studying high-speed aerodynamic characteristics of an aircraft with simulated ice type. Background Art

[0002] Commonly used icing research methods include flight tests, numerical simulations, and icing wind tunnel tests. Flight tests refer to aircraft flight tests under natural low-temperature icing meteorological conditions. Numerical simulation research methods use computers to establish icing calculation models, and then select appropriate calculation methods to obtain characteristic parameters in the icing process. Icing wind tunnel tests are a research method based on the similarity principle to simulate the icing characteristics of aircraft in flight on the ground.

[0003] Flight tests have problems such as difficulty in accurately capturing icing meteorological conditions, high test safety risks, long test cycles, and high costs. Simulation calculations are limited by the maturity of the algorithm, and the reliability of the calculation results is not high. Compared with simulation calculations, icing wind tunnel tests have higher simulation accuracy, lower technical risks, and shorter cycles than flight tests. They are a more commonly used method for studying icing characteristics.

[0004] However, there are several problems in using wind tunnel test methods to study the aerodynamic characteristics of aircraft high-speed icing:

[0005] First, the icing meteorological conditions specified in the relevant standards are relatively broad, with many combinations of temperature, droplet diameter, speed, angle of attack, altitude, etc., which cannot be fully verified in the test. It is necessary to screen out the icing conditions that produce severe icing and conduct wind tunnel test verification;

[0006] Second, after obtaining the icing types of multiple components in different icing states in the icing wind tunnel, it is necessary to screen out the critical ice types such as short-term icing (including takeoff icing, route icing, waiting icing, landing icing, etc.), anti-icing system failure ice type, unprotected surface ice type, etc. that meet the needs of airworthiness research from these states, and conduct further research on the impact of aerodynamic characteristics;

[0007] Third, the icing wind tunnel test is limited by the size of the wind tunnel and can only carry out icing tests on a section of the wing surface, and use a "hot knife" to cut out the two-dimensional ice patterns of several sections. The obtained two-dimensional ice patterns need to be converted into three-dimensional ice patterns covering the entire leading edge of the wing;

[0008] Fourth, the shape of the ice type is irregular. In order to reduce the difficulty of three-dimensional ice type transformation and subsequent simulation of ice type test model processing, the ice type needs to be simplified, but at the same time, the simplification must not have a significant change in the aerodynamic effect of the ice type;

[0009] Fifth, due to the limitations of test technical conditions, the wind speed of the icing wind tunnel test is relatively low, basically around 0.2 Ma. Only through the icing wind tunnel test, it is impossible to obtain the high-speed aerodynamic characteristics of the aircraft after icing. It is necessary to combine other wind tunnel tests to obtain the aerodynamic effects of icing at high speed. Summary of the invention

[0010] The purpose of the invention is to propose a method for studying the high-speed aerodynamic characteristics of an aircraft with simulated ice types, so as to solve the problems of screening of icing test conditions, screening of two-dimensional ice types, simplification of two-dimensional ice types, conversion of two-dimensional ice types to three-dimensional ice types, and acquisition of high-speed icing aerodynamic characteristics data.

[0011] Technical solution:

[0012] In a first aspect, a method for studying high-speed aerodynamic characteristics of an aircraft with simulated ice is provided, comprising:

[0013] By comprehensively adopting numerical simulation and wind tunnel test methods, we carried out icing test condition screening, two-dimensional ice type screening, transformation of two-dimensional ice type to three-dimensional ice type, and high-speed wind tunnel tests with simulated ice types to obtain data on the impact of aircraft high-speed icing on aerodynamic characteristics.

[0014] Furthermore, the icing test conditions were screened, including:

[0015] The control variable method is used to carry out simulation calculations of component or two-dimensional icing characteristics under different temperatures, water droplet diameters, incoming flow velocities, different attack angles, and flight altitudes to obtain the characteristic two-dimensional profile ice type.

[0016] Furthermore, the control variable method is used to sequentially carry out component or two-dimensional icing characteristics simulation calculations at different temperatures, water droplet diameters, incoming flow velocities, different angles of attack, and flight altitudes to obtain characteristic two-dimensional profile ice types, including:

[0017] The first step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the temperature with the most serious icing impact based on the impact of icing on the maximum lift coefficient and stall angle of attack;

[0018] The second step is to calculate the freezing characteristics of different water droplet diameters at a temperature where the freezing effect is more serious, according to the selected incoming flow velocity, angle of attack, flight altitude and freezing time, and obtain the two-dimensional profile ice type;

[0019] The third step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the water droplet diameter that is most seriously affected by icing based on the degree of impact of icing on the maximum lift coefficient and stall angle of attack;

[0020] Repeat steps 1 to 3 until a combination of severe operating conditions that affect all parameters is selected as the test state for wind tunnel test verification; the combination of severe operating conditions includes the temperature, droplet diameter, incoming flow velocity, different angles of attack, and flight altitude where icing has the most serious impact.

[0021] Furthermore, high-speed wind tunnel tests with simulated ice types were conducted to obtain data on the impact of high-speed icing on the aerodynamic characteristics of aircraft, including:

[0022] According to the combination of severe working conditions, three different types of critical ice shapes are confirmed: standby ice shape, failure ice shape, standby in unprotected areas, and failure ice shape;

[0023] Combined with the actual flight status of the aircraft, determine the combination status and specific installation locations of three different types of critical ice forms in the key areas of the aircraft model;

[0024] According to the wind tunnel test model scale ratio, metal 3D printing is used to manufacture simulated ice-type ice bars. On the premise of meeting the strength and stiffness requirements, the geometric shape of the ice-type ice bars is kept similar. According to the above specific installation position, they are installed at the actual icing position of the high-speed force measurement wind tunnel test host model;

[0025] High-speed force measurement wind tunnel tests with and without ice bars are carried out according to the conventional force measurement method. The high-speed icing aerodynamic characteristic parameters are obtained from the tests, and then corrected with the ice-free aerodynamic characteristic parameters using the "coefficient increment method" to obtain the aerodynamic impact of high-speed icing on the entire aircraft.

[0026] In a second aspect, a device for studying high-speed aerodynamic characteristics of an aircraft with simulated ice type is provided, comprising:

[0027] The acquisition module is used to comprehensively adopt numerical simulation and wind tunnel test methods to obtain the data on the impact of aircraft high-speed icing aerodynamic characteristics by conducting icing test condition screening, two-dimensional ice type screening, transformation of two-dimensional ice type to three-dimensional ice type, and high-speed wind tunnel tests with simulated ice types.

[0028] Furthermore, the acquisition module includes a screening unit,

[0029] The screening unit is used to carry out simulation calculations of component or two-dimensional icing characteristics under different temperatures, water droplet diameters, incoming flow velocities, different attack angles, and flight altitudes in sequence using a control variable method to obtain characteristic two-dimensional profile ice types.

[0030] Furthermore, the screening unit is specifically used for:

[0031] The first step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the temperature with the most serious icing impact based on the impact of icing on the maximum lift coefficient and stall angle of attack;

[0032] The second step is to calculate the freezing characteristics of different water droplet diameters at a temperature where the freezing effect is more serious, according to the selected incoming flow velocity, angle of attack, flight altitude and freezing time, and obtain the two-dimensional profile ice type;

[0033] The third step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the water droplet diameter that is most seriously affected by icing based on the degree of impact of icing on the maximum lift coefficient and stall angle of attack;

[0034] Repeat steps 1 to 3 until a combination of severe operating conditions that affect all parameters is selected as the test state for wind tunnel test verification; the combination of severe operating conditions includes the temperature, droplet diameter, incoming flow velocity, different angles of attack, and flight altitude where icing has the most serious impact.

[0035] Furthermore, the acquisition module also includes an acquisition unit,

[0036] The acquisition unit is specifically used for:

[0037] According to the combination of severe working conditions, three different types of critical ice shapes are confirmed: standby ice shape, failure ice shape, standby in unprotected areas, and failure ice shape;

[0038] Combined with the actual flight status of the aircraft, determine the combination status and specific installation locations of three different types of critical ice forms in the key areas of the aircraft model;

[0039] According to the wind tunnel test model scale ratio, metal 3D printing is used to manufacture simulated ice-type ice bars. On the premise of meeting the strength and stiffness requirements, the geometric shape of the ice-type ice bars is kept similar. According to the above specific installation position, they are installed at the actual icing position of the high-speed force measurement wind tunnel test host model;

[0040] High-speed force measurement wind tunnel tests with and without ice bars are carried out according to the conventional force measurement method. The high-speed icing aerodynamic characteristic parameters are obtained from the tests, and then corrected with the ice-free aerodynamic characteristic parameters using the "coefficient increment method" to obtain the aerodynamic impact of high-speed icing on the entire aircraft.

[0041] Beneficial Effects

[0042] This method provides a method for studying the aerodynamic characteristics of high-speed icing. The principle and process of the method are clear and highly operable. The method combines icing simulation calculation, icing wind tunnel test, and wind tunnel test with simulated ice bars together, and can accurately, efficiently, and safely obtain the aerodynamic impact data of high-speed icing on aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of ice types at different temperatures in a certain cross section.

[0044] Figure 2 It is a graph of lift curves for ice types at different temperatures.

[0045] Figure 3 It is a schematic diagram of ice shape at a certain cross section without water droplet diameter.

[0046] Figure 4 It is a graph of lift curves for ice types at different temperatures.

[0047] Figure 5 It is a simplified diagram of ice type.

[0048] Figure 6 It is a simplified schematic diagram of the calculation results of aerodynamic effects before and after.

[0049] Figure 7 It is a schematic diagram of the formation of three-dimensional ice type.

[0050] Figure 8 These are photos of a high-speed force measurement wind tunnel test with simulated ice type. DETAILED DESCRIPTION

[0051] The present invention provides a method for studying the high-speed aerodynamic characteristics of an aircraft with simulated ice types. The method comprehensively adopts numerical simulation and wind tunnel test methods, and obtains the influence data of the high-speed icing aerodynamic characteristics of the aircraft by carrying out icing test condition screening, two-dimensional ice type screening, transformation of two-dimensional ice types into three-dimensional ice types, and high-speed wind tunnel tests with simulated ice types.

[0052] The present invention provides a method for studying high-speed aerodynamic characteristics of an aircraft with simulated ice, comprising the following steps:

[0053] Step 1: Screening of icing test conditions. According to the aircraft flight envelope, simulate and calculate the icing characteristics of components or two-dimensional components at different temperatures, droplet diameters, incoming flow velocities, angles of attack, and flight altitudes. According to the degree of influence of icing on the maximum lift coefficient and stall angle of attack, select the working conditions with more serious icing effects.

[0054] Step 2: Two-dimensional ice type screening. Design and process icing wind tunnel test models for components, and conduct icing wind tunnel tests according to the selected icing test conditions. Obtain the two-dimensional test ice type of the measured section through the "hot knife method". Select the ice type with the greatest impact on the aerodynamic characteristics of the aircraft from multiple two-dimensional ice types of a certain section as the basis for subsequent ice type conversion. Screening can be carried out through simulation calculations of the aerodynamic impact of two-dimensional ice types. Specifically, aerodynamic CFD simulation calculations are carried out on the two-dimensional icing ice types under different icing conditions of the same measured section, and the ice type with a greater impact on the maximum lift coefficient and stall angle of attack is selected as the severe ice type.

[0055] Step 3: Simplify the two-dimensional ice type. Keep the characteristic points that reflect the extreme shape and characteristic shape, ignore the points of local contour details in the non-extreme shape area, use splines to draw the simplified ice type, and smooth the local pit shape and wave shape. Carry out CFD calculation of the aerodynamic characteristics of the ice type before and after simplification. If the change in stall angle of attack before and after simplification is less than 0.5°, the simplification is considered reasonable.

[0056] Step 4: Transformation of 2D ice type to 3D ice type. Select the 2D ice type at the wing tip and wing root after screening and simplification, and use the characteristic lines such as the ice type contour lines at both ends, the upper / lower wing surface icing limit connection lines, and the upper / lower ice angle connection lines to generate ice type surfaces in blocks using the closed curve filling method, and then use the extrapolation extension method to generate the wing leading edge ice type outside the ice type contour lines.

[0057] Step 5: Simulate ice-type high-speed wind tunnel test. According to the wind tunnel test model scale ratio, simulated ice-type ice bars are manufactured by metal 3D printing and installed in the actual icing position of the high-speed force measurement wind tunnel test host model. Carry out high-speed force measurement wind tunnel tests with and without ice bars to obtain the aerodynamic impact of high-speed icing.

[0058] Example 1

[0059] Step 1: Screening of icing test conditions. Use the control variable method to carry out simulation calculations of components or two-dimensional icing characteristics at different temperatures, water droplet diameters, flow velocities, different angles of attack, and flight altitudes to obtain characteristic two-dimensional cross-sectional ice types. Select the water droplet diameter, flow velocity, angle of attack, flight altitude, and icing time, and carry out calculations of icing characteristics at different temperatures to obtain icing types such as Figure 1 : Carry out two-dimensional CFD calculation of the aerodynamic effect of icing, compare the lift coefficient curve, and select the temperature with the most serious icing effect as -10℃ according to the influence of icing on the maximum lift coefficient and stall angle of attack. Figure 2 As shown in Figure 2; at -10℃, according to the selected incoming flow velocity, angle of attack, flight altitude and freezing time, the freezing characteristics of different water droplet diameters are calculated to obtain the freezing ice type as shown in Figure 2. Figure 3 ; Carry out two-dimensional CFD calculation of the aerodynamic effect of icing, compare the lift coefficient curve, and select the water droplet diameter of 20μm that is more seriously affected by icing according to the degree of influence of icing on the maximum lift coefficient and stall angle of attack, such as Figure 4 As shown; repeat the above steps until all severe working condition combinations that affect the parameters are selected as the test state for wind tunnel test verification.

[0060] Step 2: 2D ice type screening. Design and process the icing wind tunnel test model of the component, and conduct icing wind tunnel tests according to the selected icing test conditions. Obtain multiple 2D ice types of a certain component. Conduct simulation calculations on the aerodynamic impact of 2D ice types, compare lift curves, and screen out severe ice types that have a greater impact on the maximum lift coefficient and stall angle of attack using a method similar to step 1.

[0061] Step 3: Simplify the two-dimensional ice type of the severe ice type determined in step 2. Keep the characteristic points reflecting the extreme shape and characteristic shape, ignore the points of local contour details in the non-extreme shape area, use spline lines to draw the simplified ice type, smooth the local pit shape and wave shape, such as Figure 5 . Carry out CFD calculation of aerodynamic characteristics of ice type before and after simplification, such as Figure 6 If the stall angle of attack changes less than 0.5° before and after simplification, the simplification is considered reasonable.

[0062] Step 4: Use the simplified two-dimensional airfoil in step 3 to transform and generate a three-dimensional ice shape. Select the two-dimensional ice shape at the wing tip and wing root, and use the characteristic lines such as the ice shape contour lines at both ends, the upper / lower wing surface icing limit connection line, and the upper / lower ice angle connection line to generate the ice shape surface in blocks by using the closed curve filling method. Then use the extrapolation extension method to generate the wing leading edge ice shape outside the ice shape contour line, such as Figure 7 .

[0063] Step 5: Using the ice type generated in step 4, confirm the three different types of critical ice shapes, namely standby ice shape, failure ice shape, standby and failure ice shape in unprotected parts, according to the conditions such as liquid water content, water droplet diameter, and static temperature. Combined with the actual flight status of the aircraft, determine the combination state and specific installation position of the three different types of critical ice shapes in the key areas of the aircraft model. According to the scale ratio of the wind tunnel test model, metal 3D printing is used to manufacture simulated ice-type ice bars. While meeting the strength and stiffness requirements, the geometric shape of the ice-type ice bars is kept similar and installed in the actual icing position of the high-speed force measurement wind tunnel test host model. According to the conventional force measurement method, high-speed force measurement wind tunnel tests with and without ice bars are carried out. The high-speed icing aerodynamic characteristic parameters are obtained from the test, and the "coefficient increment method" is used to correct the aerodynamic characteristic parameters without ice, so as to obtain the aerodynamic impact of high-speed icing on the whole aircraft. Figure 8 shown.

Claims

1. A method for studying high-speed aerodynamic characteristics of an aircraft with simulated ice, characterized in that: include: By comprehensively adopting numerical simulation and wind tunnel test methods, we carried out icing test condition screening, two-dimensional ice type screening, transformation of two-dimensional ice type to three-dimensional ice type, and high-speed wind tunnel tests with simulated ice types to obtain data on the impact of aircraft high-speed icing on aerodynamic characteristics.

2. The method according to claim 1, characterized in that Conduct icing test condition screening, including: The control variable method is used to carry out simulation calculations of component or two-dimensional icing characteristics under different temperatures, water droplet diameters, incoming flow velocities, different attack angles, and flight altitudes to obtain the characteristic two-dimensional profile ice type.

3. The method according to claim 2, characterized in that The control variable method is used to carry out simulation calculations of component or two-dimensional icing characteristics at different temperatures, droplet diameters, incoming flow velocities, different angles of attack, and flight altitudes to obtain characteristic two-dimensional profile ice types, including: The first step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the temperature with the most serious icing impact based on the impact of icing on the maximum lift coefficient and stall angle of attack; The second step is to calculate the freezing characteristics of different water droplet diameters at a temperature where the freezing effect is more serious, according to the selected incoming flow velocity, angle of attack, flight altitude and freezing time, and obtain the two-dimensional profile ice type; The third step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the water droplet diameter that is most seriously affected by icing based on the degree of impact of icing on the maximum lift coefficient and stall angle of attack; Repeat steps 1 to 3 until a combination of severe operating conditions that affect all parameters is selected as the test state for wind tunnel test verification; the combination of severe operating conditions includes the temperature, droplet diameter, incoming flow velocity, different angles of attack, and flight altitude where icing has the most serious impact.

4. The method according to claim 3, characterized in that High-speed wind tunnel tests with simulated ice types are used to obtain data on the impact of high-speed icing on aircraft aerodynamic characteristics, including: According to the combination of severe working conditions, three different types of critical ice shapes are confirmed: standby ice shape, failure ice shape, standby in unprotected areas, and failure ice shape; Combined with the actual flight status of the aircraft, determine the combination status and specific installation locations of three different types of critical ice forms in the key areas of the aircraft model; According to the wind tunnel test model scale ratio, metal 3D printing is used to manufacture simulated ice-type ice bars. On the premise of meeting the strength and stiffness requirements, the geometric shape of the ice-type ice bars is kept similar. According to the above specific installation position, they are installed at the actual icing position of the high-speed force measurement wind tunnel test host model; High-speed force measurement wind tunnel tests with and without ice bars were carried out according to the conventional force measurement method. The high-speed icing aerodynamic characteristic parameters were obtained from the tests, and then corrected with the aerodynamic characteristic parameters without ice using the "coefficient increment method" to obtain the aerodynamic impact of high-speed icing on the entire aircraft.

5. A device for studying high-speed aerodynamic characteristics of an aircraft with simulated ice type, characterized in that: include: The acquisition module is used to comprehensively adopt numerical simulation and wind tunnel test methods to obtain the data on the impact of aircraft high-speed icing aerodynamic characteristics by conducting icing test condition screening, two-dimensional ice type screening, transformation of two-dimensional ice type to three-dimensional ice type, and high-speed wind tunnel tests with simulated ice types.

6. The device according to claim 5, characterized in that The acquisition module includes a screening unit, The screening unit is used to carry out simulation calculations of component or two-dimensional icing characteristics under different temperatures, water droplet diameters, incoming flow velocities, different attack angles, and flight altitudes in sequence using a control variable method to obtain characteristic two-dimensional profile ice types.

7. The device according to claim 6, characterized in that The screening unit is specifically used for: The first step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the temperature with the most serious icing impact based on the impact of icing on the maximum lift coefficient and stall angle of attack; The second step is to calculate the freezing characteristics of different water droplet diameters at a temperature where the freezing effect is more serious, according to the selected incoming flow velocity, angle of attack, flight altitude and freezing time, and obtain the two-dimensional profile ice type; The third step is to carry out CFD calculation of the aerodynamic impact of 2D ice profiles, compare the lift coefficient curves, and select the water droplet diameter that is most seriously affected by icing based on the degree of impact of icing on the maximum lift coefficient and stall angle of attack; Repeat steps 1 to 3 until a combination of severe operating conditions that affect all parameters is selected as the test state for wind tunnel test verification; the combination of severe operating conditions includes the temperature, droplet diameter, incoming flow velocity, different angles of attack, and flight altitude where icing has the most serious impact.

8. The device according to claim 7, characterized in that The acquisition module also includes an acquisition unit, The acquisition unit is specifically used for: According to the combination of severe working conditions, three different types of critical ice shapes are confirmed: standby ice shape, failure ice shape, standby in unprotected areas, and failure ice shape; Combined with the actual flight status of the aircraft, determine the combination status and specific installation locations of three different types of critical ice forms in the key areas of the aircraft model; According to the wind tunnel test model scale ratio, metal 3D printing is used to manufacture simulated ice-type ice bars. On the premise of meeting the strength and stiffness requirements, the geometric shape of the ice-type ice bars is kept similar. According to the above specific installation position, they are installed at the actual icing position of the high-speed force measurement wind tunnel test host model; High-speed force measurement wind tunnel tests with and without ice bars were carried out according to the conventional force measurement method. The high-speed icing aerodynamic characteristic parameters were obtained from the tests, and then corrected with the aerodynamic characteristic parameters without ice using the "coefficient increment method" to obtain the aerodynamic impact of high-speed icing on the entire aircraft.

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