Method for calculating incidence angle of probe based on large incidence angle
By constructing a table of probe angle of attack coefficient, Mach number coefficient and total pressure coefficient, combined with the historical test data of distributed atmospheric data computers and real-time pressure data, the problem of inaccurate angle of attack calculation at large angle of attack is solved, and more accurate calculation of probe angle of attack and probe Mach number is achieved.
Patent Information
- Application Number
- CN202411870091.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-04-25
AI Technical Summary
When the probe angle of attack is large due to high aircraft maneuverability requirements or the distributed position of distributed atmospheric data computers, conventional calculation methods cannot correctly calculate the probe angle of attack.
By obtaining the historical test data of the computer for blowing air tests in the wind tunnel by a distributed atmospheric data, a table of probe angle of attack coefficient, Mach coefficient and total pressure coefficient, and based on the collected indicator total pressure, upper angle of attack pressure and lower angle of attack pressure, an appropriate number table is selected from the number table for calculation, and the probe angle of attack and Mach number of probe are calculated.
The probe angle of attack and the probe Mach number can be accurately calculated at a large angle of attack, which solves the problem of inaccurate probe angle of attack calculation and improves the accuracy and reliability of the calculation.
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Figure CN119884561A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of atmospheric detection systems, and in particular to a method for calculating the angle of attack of a probe under large angles of attack. Background Art
[0002] Angle of attack is one of the important parameters of aircraft flight. Conventional aircraft usually use angle of attack sensors to collect the current angle of attack. However, with the development of technology, distributed air data computers can simultaneously collect indicated total pressure, upper angle of attack pressure, and lower angle of attack pressure to calculate the probe angle of attack at the current position, and solve the angle of attack based on the probe angle of attack. However, due to the requirements of aircraft maneuverability and the distribution of distributed air data computers, the probe angle of attack will appear larger. At this time, the upper angle of attack pressure or the lower angle of attack pressure is greater than the indicated total pressure. Therefore, it is necessary to study a method for calculating the probe angle of attack based on the distributed air data computer at large angles of attack to solve the problem of calculating the probe angle of attack at large angles of attack. Summary of the invention
[0003] In view of this, an embodiment of the present application provides a method for calculating the probe angle of attack at a large angle of attack, with the aim of solving the problem that the upper angle of attack pressure or the lower angle of attack pressure is greater than the total pressure when the probe angle of attack is large due to high aircraft maneuverability requirements or the distribution location of a distributed atmospheric data computer. At this time, conventional calculation methods cannot correctly calculate the probe angle of attack.
[0004] The present application provides a method for calculating the angle of attack of a probe under a large angle of attack, the method comprising:
[0005] Obtain historical test data of wind tests conducted by the distributed atmospheric data computer in the wind tunnel;
[0006] Constructing a first set of numerical tables, and solving the probe angle of attack in the historical test data according to the first set of numerical tables;
[0007] When the calculated attack angle of the probe exceeds a preset angle range, constructing a second set of numerical tables under a positive attack angle and a third set of numerical tables under a negative attack angle;
[0008] The first group of tables, the second group of tables and the third group of tables all include a table of probe angle of attack coefficients, a table of probe Mach number coefficients and a table of probe total pressure coefficients;
[0009] Collect new indicated total pressure, upper angle of attack pressure and lower angle of attack pressure from the distributed air data computer for wind blowing test;
[0010] According to the difference between the indicated total pressure and the pressure at the upper angle of attack and the difference between the indicated total pressure and the pressure at the lower angle of attack, a set of numerical tables is selected from the three sets of numerical tables, and the probe angle of attack and the probe Mach number are solved according to the probe angle of attack coefficient numerical table and the probe Mach number coefficient numerical table in the set of numerical tables;
[0011] The probe total pressure is calculated based on the calculated probe angle of attack and probe Mach number and the probe total pressure coefficient table in this group of tables.
[0012] According to a specific implementation of the embodiment of the present application, the preset angle range is -40° to 40°.
[0013] According to a specific implementation of an embodiment of the present application, when the calculated probe angle of attack exceeds a preset angle range, a second set of number tables under a positive angle of attack and a third set of number tables under a negative angle of attack are constructed, including:
[0014] When the calculated probe attack angle exceeds 40°, it is in the high attack angle area under the positive attack angle, and a part of the pressure in the upper attack angle pressure is added to the indicated total pressure as the indicated total pressure under the high attack angle, and a second set of data tables under the positive attack angle is constructed;
[0015] When the solved probe angle of attack exceeds -40°, it is in the large angle of attack area under negative angle of attack, and a part of the pressure in the low angle of attack pressure is added to the indicated total pressure as the indicated total pressure under large angle of attack, so as to construct the third set of numerical tables under negative angle of attack.
[0016] According to a specific implementation of an embodiment of the present application, the expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the first set of numerical tables are:
[0017] Cpma=Qc i / Ps i,
[0018] Cpa=Pa / Qci,
[0019] Cpt=△Pt / Qc,
[0020] in,
[0021] Qc i=Pt i-Ps i,
[0022] Psi=(Pu+Pd) / 2,
[0023] Pa=Pd-Pu,
[0024] △Pt=Pt i-Pt,
[0025] Qc=Pt-Psi,
[0026] Wherein, Cpa is the first probe angle of attack coefficient, Cpma is the first probe Mach number coefficient, Cpt is the first probe total pressure coefficient, Qci is the first indicated dynamic pressure, Pti is the indicated total pressure, Psi is the indicated static pressure, Pa is the pressure difference between the upper and lower angles of attack, Pu is the upper angle of attack pressure, Pd is the lower angle of attack pressure, △Pt is the pressure difference between the indicated total pressure and the probe total pressure, Pt is the probe total pressure, and Qc is the probe dynamic pressure.
[0027] According to a specific implementation of an embodiment of the present application, the expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the second set of numerical tables are:
[0028] Cpma1=Qc i 1 / Ps i,
[0029] Cpa1=Pa / Qc i 1,
[0030] Cpt1=△Pt1 / Qc,
[0031] in,
[0032] Qc i 1=Pt1-Ps i,
[0033] Psi=(Pu+Pd) / 2,
[0034] Pa=Pd-Pu,
[0035] △Pt1=Pt1-Pt,
[0036] Qc=Pt-Psi,
[0037] Pt1=a*Pd+(1-a)*Pt i,
[0038] Wherein, Cpa1 is the second probe angle of attack coefficient, Cpma1 is the second probe Mach number coefficient, Cpt1 is the second probe total pressure coefficient, Qc i 1 is the second indicated dynamic pressure, △Pt1 is the pressure difference between the indicated total pressure and the probe total pressure at the first largest angle of attack, Pt1 is the indicated total pressure at the first largest angle of attack, and a is a coefficient less than 1.
[0039] According to a specific implementation of an embodiment of the present application, the expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the third set of numerical tables are:
[0040] Cpma2=Qc i2 / Ps i,
[0041] Cpa2=Pa / Qc i2,
[0042] Cpt2=△Pt2 / Qc,
[0043] in:
[0044] Qc i2=Pt2-Ps i,
[0045] Psi=(Pu+Pd) / 2,
[0046] Pa=Pd-Pu,
[0047] △Pt2=Pt2-Pt,
[0048] Qc=Pt-Psi,
[0049] Pt2=b*Pu+(1-a)*Pt i,
[0050] Wherein, Cpa2 is the third probe angle of attack coefficient, Cpma2 is the third probe Mach number coefficient, Cpt2 is the third probe total pressure coefficient, Qci2 is the third indicated dynamic pressure, △Pt2 is the pressure difference between the indicated total pressure and the probe total pressure at the second largest angle of attack, Pt2 is the indicated total pressure at the second largest angle of attack, and b is a coefficient less than 1.
[0051] According to a specific implementation of an embodiment of the present application, a set of numerical tables is selected from the three sets of numerical tables based on the difference between the indicated total pressure and the pressure at the upper angle of attack and the difference between the indicated total pressure and the pressure at the lower angle of attack, including:
[0052] When the difference between the indicated total pressure and the pressure at the upper angle of attack is greater than zero and the difference between the indicated total pressure and the pressure at the lower angle of attack is greater than zero, the first group of digital tables is selected from the three groups of digital tables;
[0053] When the difference between the collected indicated total pressure and the upper angle of attack pressure is less than zero, the second group of digital tables is selected from the three groups of digital tables, otherwise the third group of digital tables is selected.
[0054] According to a specific implementation of the embodiment of the present application, the method further includes:
[0055] When the first set of number tables is selected from the three sets of number tables, and the probe angle of attack obtained by solution is at the boundary of the high angle of attack region under the positive angle of attack, the probe angle of attack and the probe Mach number are solved again using the second set of number tables, and the angle range of the boundary of the high angle of attack region under the positive angle of attack is 30° to 40°;
[0056] The probe total pressure is calculated based on the probe angle of attack and the probe Mach number obtained by recalculation and the probe total pressure coefficient table in the set of tables.
[0057] According to a specific implementation of the embodiment of the present application, the method further includes:
[0058] When the first set of number tables is selected from the three sets of number tables, and the probe angle of attack obtained by solution is at the boundary of the high angle of attack region under the negative angle of attack, the probe angle of attack and the probe Mach number are solved again using the third set of number tables, and the angle range of the boundary of the high angle of attack region under the negative angle of attack is -40° to -30°;
[0059] The probe total pressure is calculated based on the probe angle of attack and the probe Mach number obtained by recalculation and the probe total pressure coefficient table in the set of tables.
[0060] Beneficial effects:
[0061] The calculation method of the probe angle of attack at a large angle of attack in the embodiment of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0062] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0063] Figure 1 It is a flow chart of a method for calculating the angle of attack of a probe under a large angle of attack according to an embodiment of the present invention;
[0064] Figure 2 is a diagram corresponding to a Cpa number table according to an embodiment of the present invention;
[0065] Figure 3 is a diagram corresponding to a Cpma table according to an embodiment of the present invention;
[0066] Figure 4 is a diagram corresponding to the Cpa1 numerical table according to an embodiment of the present invention;
[0067] Figure 5 is a diagram corresponding to the Cpma1 table according to an embodiment of the present invention;
[0068] Figure 6 is a diagram corresponding to the Cpa2 numerical table according to an embodiment of the present invention;
[0069] Figure 7 A diagram corresponding to a Cpma3 table according to an embodiment of the present invention;
[0070] Figure 8 The present invention is another flowchart of a method for calculating the probe angle of attack at a large angle of attack according to an embodiment of the present invention. DETAILED DESCRIPTION
[0071] The embodiments of the present application are described in detail below with reference to the accompanying drawings.
[0072] The following describes the implementation methods of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the following embodiments and the features in the embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work belong to the scope of protection of the present application.
[0073] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present application, it should be understood by those skilled in the art that an aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein can be used to implement this device and / or practice this method.
[0074] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present application. The illustrations only show the components related to the present application rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed at will, and the component layout may also be more complicated.
[0075] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.
[0076] The present application embodiment provides a method for calculating the angle of attack of the probe under a large angle of attack. Figures 1 to 8 Describe in detail.
[0077] In one embodiment, referring to Figure 1 The calculation method of the probe angle of attack at a large angle of attack includes the following steps:
[0078] Step S101, obtaining historical test data of a wind test conducted by a distributed atmospheric data computer in a wind tunnel;
[0079] Step S102, constructing a first set of number tables, and calculating the probe angle of attack in the historical test data according to the first set of number tables;
[0080] Step S103: when the calculated attack angle of the probe exceeds a preset angle range, construct a second set of number tables under a positive attack angle and a third set of number tables under a negative attack angle;
[0081] Step S104, the first set of tables, the second set of tables and the third set of tables all include a probe angle of attack coefficient table, a probe Mach number coefficient table and a probe total pressure coefficient table;
[0082] Step S105, collecting new indicated total pressure, upper angle of attack pressure and lower angle of attack pressure of the wind blowing test by the distributed atmospheric data computer;
[0083] Step S106, selecting a set of digital tables from the three sets of digital tables according to the difference between the indicated total pressure and the upper angle of attack pressure and the difference between the indicated total pressure and the lower angle of attack pressure, and calculating the probe angle of attack and the probe Mach number according to the probe angle of attack coefficient digital table and the probe Mach number coefficient digital table in the set of digital tables;
[0084] Step S107, calculating the probe total pressure according to the calculated probe angle of attack and probe Mach number and the probe total pressure coefficient table in the set of tables.
[0085] In one embodiment, the preset angle range is -40° to 40°. That is, when the probe angle of attack is within the preset angle range, the first set of tables can be directly used to calculate the probe angle of attack, the probe Mach number and the probe total pressure. When the probe angle of attack exceeds the preset angle range, it is necessary to adjust to the second and third sets of tables for calculation.
[0086] Specifically, when the calculated probe angle of attack exceeds a preset angle range, a second set of number tables under a positive angle of attack and a third set of number tables under a negative angle of attack are constructed, including:
[0087] When the calculated probe attack angle exceeds 40°, it is in the high attack angle area under the positive attack angle, and a part of the pressure in the upper attack angle pressure is added to the indicated total pressure as the indicated total pressure under the high attack angle, and a second set of data tables under the positive attack angle is constructed;
[0088] When the solved probe angle of attack exceeds -40°, it is in the large angle of attack area under negative angle of attack, and a part of the pressure in the low angle of attack pressure is added to the indicated total pressure as the indicated total pressure under large angle of attack, so as to construct the third set of numerical tables under negative angle of attack.
[0089] In one embodiment, the expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the first set of numerical tables are:
[0090] Cpma=Qc i / Ps i,
[0091] Cpa=Pa / Qci,
[0092] Cpt=△Pt / Qc,
[0093] in,
[0094] Qc i=Pt i-Ps i,
[0095] Psi=(Pu+Pd) / 2,
[0096] Pa=Pd-Pu,
[0097] △Pt=Pt i-Pt,
[0098] Qc=Pt-Psi,
[0099] Wherein, Cpa is the first probe angle of attack coefficient, Cpma is the first probe Mach number coefficient, Cpt is the first probe total pressure coefficient, Qci is the first indicated dynamic pressure, Pti is the indicated total pressure, Psi is the indicated static pressure, Pa is the pressure difference between the upper and lower angles of attack, Pu is the upper angle of attack pressure, Pd is the lower angle of attack pressure, △Pt is the pressure difference between the indicated total pressure and the probe total pressure, Pt is the probe total pressure, and Qc is the probe dynamic pressure.
[0100] In one embodiment, the expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the second set of numerical tables are:
[0101] Cpma1=Qc i 1 / Ps i,
[0102] Cpa1=Pa / Qc i 1,
[0103] Cpt1=△Pt1 / Qc,
[0104] in,
[0105] Qc i 1=Pt1-Ps i,
[0106] Psi=(Pu+Pd) / 2,
[0107] Pa=Pd-Pu,
[0108] △Pt1=Pt1-Pt,
[0109] Qc=Pt-Psi,
[0110] Pt1=a*Pd+(1-a)*Pt i,
[0111] Wherein, Cpa1 is the second probe angle of attack coefficient, Cpma1 is the second probe Mach number coefficient, Cpt1 is the second probe total pressure coefficient, Qc i 1 is the second indicated dynamic pressure, △Pt1 is the pressure difference between the indicated total pressure and the probe total pressure at the first largest angle of attack, Pt1 is the indicated total pressure at the first largest angle of attack, and a is a coefficient less than 1.
[0112] In one embodiment, the expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the third set of numerical tables are:
[0113] Cpma2=Qc i2 / Ps i,
[0114] Cpa2=Pa / Qc i2,
[0115] Cpt2=△Pt2 / Qc,
[0116] in:
[0117] Qc i 2=Pt 2 - Ps i,
[0118] Psi=(Pu+Pd) / 2,
[0119] Pa=Pd-Pu,
[0120] △Pt2=Pt2-Pt,
[0121] Qc=Pt-Psi,
[0122] Pt2=b*Pu+(1-a)*Pt i,
[0123] Wherein, Cpa2 is the third probe angle of attack coefficient, Cpma2 is the third probe Mach number coefficient, Cpt2 is the third probe total pressure coefficient, Qci2 is the third indicated dynamic pressure, △Pt2 is the pressure difference between the indicated total pressure and the probe total pressure at the second largest angle of attack, Pt2 is the indicated total pressure at the second largest angle of attack, and b is a coefficient less than 1.
[0124] In one embodiment, according to the difference between the indicated total pressure and the pressure at the upper angle of attack and the difference between the indicated total pressure and the pressure at the lower angle of attack, a group of digital tables is selected from the three groups of digital tables, including:
[0125] When the difference between the indicated total pressure and the pressure at the upper angle of attack is greater than zero and the difference between the indicated total pressure and the pressure at the lower angle of attack is greater than zero, the first group of digital tables is selected from the three groups of digital tables;
[0126] When the difference between the collected indicated total pressure and the upper angle of attack pressure is less than zero, the second group of digital tables is selected from the three groups of digital tables, otherwise the third group of digital tables is selected.
[0127] In the specific implementation, the calculation of the probe angle of attack is first carried out by blowing air on the distributed atmospheric data computer in a wind tunnel, recording the indicated total pressure, upper angle of attack pressure, lower angle of attack pressure, probe Mach number, probe angle of attack, and probe total pressure. With the support of the blowing data, the Cpa, Cpma, and Cpt tables are first established, i.e., the first set of tables. According to the wind tunnel data and the expressions of the probe angle of attack coefficient, probe Mach number coefficient, and probe total pressure coefficient in the above first set of tables, the Cpa, Cpma, and Cpt tables under different probe Mach numbers and different probe angles of attack are established.
[0128] However, when a large probe angle of attack occurs, the Cpa and Cpma tables established according to the expressions in the first set of tables will appear. Figure 2 and Figure 3 When the probe angle of attack is large, it will be difficult to correctly calculate the probe angle of attack and the probe Mach number because the data in the Cpa and Cpma tables are not monotonous.
[0129] When there is no extra aircraft parameter information, we can only rely on the known indicated total pressure, upper angle of attack pressure, and lower angle of attack pressure to solve the probe angle of attack, probe Mach number, and probe total pressure. When a large probe angle of attack occurs, the upper angle of attack pressure hole or the lower angle of attack pressure hole of the probe will feel more total pressure components than the total pressure hole. Therefore, part of the pressure felt in the upper angle of attack pressure or the lower angle of attack pressure can be accumulated with the indicated total pressure as the indicated total pressure at a large angle of attack to solve Cpa, Cpma, and Cpt. The specific method is as follows:
[0130] Assuming that the current area is in the high angle of attack area under a positive angle of attack, the low angle of attack pressure hole will feel more total pressure components. At this time, the total pressure calculated in Cpa, Cpma, and Cpt can be equivalent to the sum of the low angle of attack pressure component and the indicated total pressure. However, due to the different probe angles of attack, the proportion of the low angle of attack pressure component to the total pressure component is also different, so a fixed value can be fixed, that is, at different probe angles of attack, the proportion coefficient of the low angle of attack pressure component is the same. Therefore, in the high angle of attack area under a positive angle of attack, Pt1 = a*Pd+(1-a)Pti, different probes will lead to different values of a. At this time, the appropriate value of a can be selected according to the actual data of the wind tunnel. Therefore, the Cpa1, Cpma1, and Cpt1 tables in the high angle of attack area under a positive angle of attack are constructed, and the method for establishing the table is as follows:
[0131] Cpma1=Qc i 1 / Ps i,
[0132] Cpa1=Pa / Qc i 1,
[0133] Cpt1=△Pt1 / Qc,
[0134] in,
[0135] Qc i 1=Pt1-Ps i,
[0136] Psi=(Pu+Pd) / 2,
[0137] Pa=Pd-Pu,
[0138] △Pt1=Pt1-Pt,
[0139] Qc=Pt-Psi.
[0140] Therefore, the Cpa1 and Cpma1 tables constructed on this basis are shown in the attached figure Figure 4 and Figure 5 . It can be seen from the figure that in the high angle of attack area under the positive angle of attack, the values in the Cpa1 and Cpma1 tables are monotonically the same. Therefore, when the indicated total pressure, the upper angle of attack pressure, and the lower angle of attack pressure are collected, the Cpa1 value and the Cpma1 value can be calculated. According to the calculated Cpa1 value and Cpma1 value, the probe angle of attack and the probe Mach number in the high angle of attack area under the current positive angle of attack can be correctly solved by searching in the corresponding chart.
[0141] For the high angle of attack area under negative angle of attack, the upper angle of attack pressure hole will feel more total pressure components. At this time, the total pressure calculated in Cpa, Cpma, and Cpt can be equivalent to the sum of the upper angle of attack pressure component and the indicated total pressure. The construction logic is the same as that of the high angle of attack area under positive angle of attack. At this time, Pt2 = b*Pu+(1-b)*Pt i, and the constructed Cpa2, Cpma2, and Cpt2 are as follows:
[0142] Cpma2=Qc i2 / Ps i,
[0143] Cpa2=Pa / Qc i2,
[0144] Cpt2=△Pt2 / Qc,
[0145] in:
[0146] Qc i 2=Pt 2 - Ps i,
[0147] Psi=(Pu+Pd) / 2,
[0148] Pa=Pd-Pu,
[0149] △Pt2=Pt2-Pt,
[0150] Qc=Pt-Psi.
[0151] The Cpa2 and Cpma2 tables constructed on this basis are attached. Figure 6 and Figure 7It can be seen from the figure that in the high angle of attack region under negative angle of attack, the values in the Cpa2 and Cpma2 tables are monotonically the same, which will correctly solve the probe angle of attack and probe Mach number in the high angle of attack region under the current negative angle of attack.
[0152] After constructing the Cpa, Cpma, Cpt, Cpa1, Cpma1, Cpt1, Cpa2, Cpma2, and Cpt2 tables according to the above table building method, when the indicated total pressure, upper angle of attack pressure, and lower angle of attack pressure are collected, it can be determined which area of the table to use based on the difference between the indicated total pressure and the upper angle of attack pressure and the lower angle of attack pressure.
[0153] exist Figures 2 to 7 In, for Figure 2 Cpa curve, Figure 4 Cpa1 curve, Figure 6 The meaning of the Cpa2 curve is the Cpa value as the probe angle of attack increases at the same probe Mach number; Figure 3 Cpma Figure 5 Cpma1, Figure 7 The Cpma2 curve means the Cpma value as the probe Mach number increases at the same probe angle of attack.
[0154] In order to avoid inaccurate calculation of Cpa, Cpma and Cpt at the critical point of the probe angle of attack in the large angle of attack area, the large probe angle of attack table (the second set of tables or the third set of tables) can be used to recalculate the probe angle of attack, probe Mach number and probe total pressure.
[0155] In one embodiment, referring to Figure 8 , the method further comprises:
[0156] When the first set of number tables is selected from the three sets of number tables, and the probe angle of attack obtained by solution is at the boundary of the high angle of attack region under the positive angle of attack, the probe angle of attack and the probe Mach number are solved again using the second set of number tables, and the angle range of the boundary of the high angle of attack region under the positive angle of attack is 30° to 40°;
[0157] The probe total pressure is calculated based on the probe angle of attack and the probe Mach number obtained by recalculation and the probe total pressure coefficient table in the set of tables.
[0158] In one embodiment, referring to Figure 8 , the method further comprises:
[0159] When the first set of number tables is selected from the three sets of number tables, and the probe angle of attack obtained by solution is at the boundary of the high angle of attack region under the negative angle of attack, the probe angle of attack and the probe Mach number are solved again using the third set of number tables, and the angle range of the boundary of the high angle of attack region under the negative angle of attack is -40° to -30°;
[0160] The probe total pressure is calculated based on the probe angle of attack and the probe Mach number obtained by recalculation and the probe total pressure coefficient table in the set of tables.
[0161] In one embodiment, the method of the present application is described in detail, referring to Figure 8 , including the following steps:
[0162] S1. Collect indicated total pressure, upper angle of attack pressure, and lower angle of attack pressure;
[0163] S2, determining whether the indicated total pressure is greater than the pressure at the upper angle of attack and greater than the pressure at the lower angle of attack, if so, executing S3, if not, executing S8;
[0164] S3, calculating the probe angle of attack and the probe Mach number according to the indicated total pressure, the upper angle of attack pressure, the lower angle of attack pressure, the Cpa table and the Cpma table, and executing S4;
[0165] S4, determining whether the probe angle of attack is in the critical region of a large angle of attack under a positive angle of attack, if so, executing S5, if not, executing S6;
[0166] S5, calculating the probe angle of attack and the probe Mach number according to the indicated total pressure, the upper angle of attack pressure, the lower angle of attack pressure, and the Cpa1 table and the Cpma1 table, and executing S11;
[0167] S6, determining whether the probe angle of attack is in the critical region of a large angle of attack under a negative angle of attack, if so, executing S7, if not, executing S11;
[0168] S7, calculating the probe angle of attack and the probe Mach number according to the indicated total pressure, the upper angle of attack pressure, the lower angle of attack pressure, the Cpa2 table and the Cpma2 table, and executing S11;
[0169] S8, determining whether the indicated total pressure is less than the upper angle of attack pressure, if so, executing S9, if not, executing S10;
[0170] S9, calculating the probe angle of attack and the probe Mach number according to the indicated total pressure, the upper angle of attack pressure, the lower angle of attack pressure, and the Cpa1 table and the Cpma1 table, and executing S11;
[0171] S10, calculating the probe angle of attack and the probe Mach number according to the indicated total pressure, the upper angle of attack pressure, the lower angle of attack pressure, the Cpa2 table and the Cpma2 table, and executing S11;
[0172] S11. Calculate the probe total pressure based on the probe angle of attack, probe Mach number and the corresponding Cpt table.
[0173] In the above embodiment, the distributed atmospheric data computer has low requirements on the probe angle of attack due to its good distribution position or when the aircraft maneuverability requirement is not high. However, when a large probe angle of attack occurs, the distributed atmospheric data computer will not be able to correctly calculate the probe angle of attack and the probe Mach number according to conventional calculations. However, we can correctly solve the probe angle of attack, probe Mach number and probe total pressure at any probe angle of attack and any probe Mach number based on the indicated total pressure, upper angle of attack pressure and lower angle of attack pressure collected by the distributed atmospheric data computer according to the above table construction and software algorithm.
[0174] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.
Claims
1. A method for calculating the angle of attack of a probe at a large angle of attack, characterized in that: The method comprises: Obtain historical test data of wind tests conducted by the distributed atmospheric data computer in the wind tunnel; Constructing a first set of numerical tables, and solving the probe angle of attack in the historical test data according to the first set of numerical tables; When the calculated attack angle of the probe exceeds a preset angle range, constructing a second set of numerical tables under a positive attack angle and a third set of numerical tables under a negative attack angle; The first group of tables, the second group of tables and the third group of tables all include a table of probe angle of attack coefficients, a table of probe Mach number coefficients and a table of probe total pressure coefficients; Collect new indicated total pressure, upper angle of attack pressure and lower angle of attack pressure from the distributed air data computer for wind blowing test; According to the difference between the indicated total pressure and the pressure at the upper angle of attack and the difference between the indicated total pressure and the pressure at the lower angle of attack, a set of numerical tables is selected from the three sets of numerical tables, and the probe angle of attack and the probe Mach number are solved according to the probe angle of attack coefficient numerical table and the probe Mach number coefficient numerical table in the set of numerical tables; The probe total pressure is calculated based on the calculated probe angle of attack and probe Mach number and the probe total pressure coefficient table in this group of tables.
2. The method for calculating the probe angle of attack at a large angle of attack according to claim 1, characterized in that: The preset angle range is -40° to 40°.
3. The method for calculating the probe angle of attack at a large angle of attack according to claim 2, characterized in that: When the calculated probe angle of attack exceeds a preset angle range, a second set of number tables under a positive angle of attack and a third set of number tables under a negative angle of attack are constructed, including: When the calculated probe attack angle exceeds 40°, it is in the high attack angle area under the positive attack angle, and a part of the pressure in the upper attack angle pressure is added to the indicated total pressure as the indicated total pressure under the high attack angle, and a second set of data tables under the positive attack angle is constructed; When the solved probe angle of attack exceeds -40°, it is in the large angle of attack area under negative angle of attack, and a part of the pressure in the low angle of attack pressure is added to the indicated total pressure as the indicated total pressure under large angle of attack, so as to construct the third set of numerical tables under negative angle of attack.
4. The method for calculating the probe angle of attack at a large angle of attack according to claim 3, characterized in that: The expressions of the probe angle of attack coefficient, probe Mach number coefficient and probe total pressure coefficient in the first set of numerical tables are: Cpma=Qci / Psi, Cpa=Pa / Qci, Cpt=△Pt / Qc, in, Qci=Pti-Psi, Psi=(Pu+Pd) / 2, Pa=Pd-Pu, △Pt=Pti-Pt, Qc=Pt-Psi, Wherein, Cpa is the first probe angle of attack coefficient, Cpma is the first probe Mach number coefficient, Cpt is the first probe total pressure coefficient, Qci is the first indicated dynamic pressure, Pti is the indicated total pressure, Psi is the indicated static pressure, Pa is the pressure difference between the upper and lower angles of attack, Pu is the upper angle of attack pressure, Pd is the lower angle of attack pressure, △Pt is the pressure difference between the indicated total pressure and the probe total pressure, Pt is the probe total pressure, and Qc is the probe dynamic pressure.
5. The method for calculating the probe angle of attack at a large angle of attack according to claim 3, characterized in that: The expressions of the probe angle of attack coefficient, probe Mach number coefficient and probe total pressure coefficient in the second set of numerical tables are: Cpma1=Qci 1 / Psi, Cpa1=Pa / Qci 1, Cpt1=△Pt1 / Qc, in, Qci 1=Pt1-Psi, Psi=(Pu+Pd) / 2, Pa=Pd-Pu, △Pt1=Pt1-Pt, Qc=Pt-Psi, Pt1=a*Pd+(1-a)*Pti, Wherein, Cpa1 is the second probe angle of attack coefficient, Cpma1 is the second probe Mach number coefficient, Cpt1 is the second probe total pressure coefficient, Qci 1 is the second indicated dynamic pressure, △Pt1 is the pressure difference between the indicated total pressure and the probe total pressure at the first largest angle of attack, Pt1 is the indicated total pressure at the first largest angle of attack, and a is a coefficient less than 1.
6. The method for calculating the probe angle of attack at a large angle of attack according to claim 3, characterized in that: The expressions of the probe angle of attack coefficient, the probe Mach number coefficient and the probe total pressure coefficient in the third set of numerical tables are: Cpma2=Qci2 / Psi, Cpa2=Pa / Qci2, Cpt2=△Pt2 / Qc, in: Qci2=Pt2-Psi, Psi=(Pu+Pd) / 2, Pa=Pd-Pu, △Pt2=Pt2-Pt, Qc=Pt-Psi, Pt2=b*Pu+(1-a)*Pti, Wherein, Cpa2 is the third probe angle of attack coefficient, Cpma2 is the third probe Mach number coefficient, Cpt2 is the third probe total pressure coefficient, Qci2 is the third indicated dynamic pressure, △Pt2 is the pressure difference between the indicated total pressure and the probe total pressure at the second largest angle of attack, Pt2 is the indicated total pressure at the second largest angle of attack, and b is a coefficient less than 1.
7. The method for calculating the probe angle of attack at a large angle of attack according to claim 3, characterized in that: According to the difference between the indicated total pressure and the pressure at the upper angle of attack and the difference between the indicated total pressure and the pressure at the lower angle of attack, a group of digital tables is selected from the three groups of digital tables, including: When the difference between the indicated total pressure and the pressure at the upper angle of attack is greater than zero and the difference between the indicated total pressure and the pressure at the lower angle of attack is greater than zero, the first group of digital tables is selected from the three groups of digital tables; When the difference between the collected indicated total pressure and the upper angle of attack pressure is less than zero, the second group of digital tables is selected from the three groups of digital tables, otherwise the third group of digital tables is selected.
8. The method for calculating the probe angle of attack at a large angle of attack according to claim 1, characterized in that: The method further comprises: When the first set of number tables is selected from the three sets of number tables, and the probe angle of attack obtained by solution is at the boundary of the high angle of attack region under the positive angle of attack, the probe angle of attack and the probe Mach number are solved again using the second set of number tables, and the angle range of the boundary of the high angle of attack region under the positive angle of attack is 30° to 40°; The probe total pressure is calculated based on the probe angle of attack and the probe Mach number obtained by recalculation and the probe total pressure coefficient table in the set of tables.
9. The method for calculating the probe angle of attack at a large angle of attack according to claim 7, characterized in that: The method further comprises: When the first set of number tables is selected from the three sets of number tables, and the probe angle of attack obtained by solution is at the boundary of the high angle of attack region under the negative angle of attack, the probe angle of attack and the probe Mach number are solved again using the third set of number tables, and the angle range of the boundary of the high angle of attack region under the negative angle of attack is -40° to -30°; The probe total pressure is calculated based on the probe angle of attack and the probe Mach number obtained by recalculation and the probe total pressure coefficient table in the set of tables.