Runway friction coefficient measuring method

Abstract

The invention belongs to the technical field of aircraft performance design and aircraft guarantee, and particularly relates to a runway friction coefficient measuring method. Comprising the following steps: step 1, in a set taxiing speed range, four aircrafts respectively carry out accelerated taxiing tests according to three engine operation strategies, and aircraft operation parameters are measured through an airborne sensor; and 2, eliminating the influence of engine data on a test result according to a specific aircraft dynamics model, and calculating to obtain a friction coefficient mu of the aircraft and the runway. And step 3, selecting other test aircraft mass conditions, and obtaining the friction coefficient mu of the aircraft and the runway under different aircraft mass m conditions according to the mode, so as to realize the correction work of the take-off performance model. The related data is obtained through the low-speed ground sliding test and used for calculating the rolling friction coefficient of the aircraft in the unfamiliar airport, the take-off performance model is corrected, and the more accurate take-off performance of the aircraft in the target airport is obtained.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft performance design and aircraft support, and in particular relates to a method for measuring a runway friction coefficient. Background Art

[0002] The takeoff performance model includes the aircraft's weight data, aerodynamic data, power data, aircraft-runway friction data, etc. The more accurate the data in the takeoff performance model, the more consistent the calculation results of the takeoff performance will be with the test flight results.

[0003] The friction data μ between the aircraft and the runway during takeoff is used as the factor affecting the acceleration in the aircraft speed direction. ALL The smaller / W is, the greater the effect of μ on the acceleration in the velocity direction. Large aircraft often have a smaller thrust-to-weight ratio, so designers pay attention to the friction data μ between the aircraft and the runway.

[0004] The friction coefficient μ between the aircraft and the runway is affected by many factors, including the material and texture of the runway, the aircraft's tires and landing gear, etc. Of course, if the friction coefficient μ between the aircraft and the runway can be directly measured, such results are suitable for direct application to the takeoff performance model.

[0005] At present, there are deficiencies in the measurement of runway friction coefficient of large aircraft at unfamiliar airports. First, the runway friction coefficient of large aircraft has a significant impact on takeoff performance. Accurately understanding the friction coefficient of large aircraft at a given airport can effectively calibrate the takeoff performance model; secondly, directly using large aircraft to measure the friction coefficient μ between the aircraft and the runway can avoid the use of airport runway friction measurement vehicles and the correction work between the two; finally, after the large aircraft calibrates the takeoff performance model at an unfamiliar airport, the accuracy of the takeoff performance parameters of each transport aircraft can be further improved.

[0006] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0007] The purpose of the present application is to provide a method for measuring the friction coefficient of a runway to solve at least one problem existing in the prior art.

[0008] The technical solution of this application is:

[0009] The first aspect of the present application provides a method for measuring a runway friction coefficient, comprising:

[0010] Step 1: Within the set taxiing speed range, the four-engine aircraft conducts accelerated taxiing tests according to three engine operation strategies, and measures the aircraft operation parameters through airborne sensors;

[0011] Step 2: According to the specific aircraft dynamics model, eliminate the influence of engine data on the test results and calculate the friction coefficient μ between the aircraft and the runway.

[0012] In at least one embodiment of the present application, in step one, the set gliding speed range is 10km / h to 30km / h.

[0013] In at least one embodiment of the present application, in step 1, the three engine operation strategies are:

[0014] Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters;

[0015] Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters;

[0016] Start the four inner and outer engines, with the throttle position of the two outer engines at L1 and the throttle position of the two inner engines at L2. The aircraft continues to accelerate and the operating parameters of the aircraft are measured.

[0017] In at least one embodiment of the present application, in step 2, the specific aircraft dynamics model is:

[0018] 2×F 外 -μ(W-qCL)-qCD=ma 1

[0019] 2×F 内 -μ(W-qCL)-qCD=ma 2

[0020] 4×F-μ(W-qCL)-qCD=ma 3

[0021] Among them, F 外 is the average thrust of the two outer engines when the throttle position is L1, F 内 is the average thrust of the two inner engines when the throttle position is L2, F is the average thrust of the four engines when the throttle position is L1 and L2, W is the weight of the aircraft during the taxiing process, q is the dynamic pressure of the aircraft during the taxiing process, CL is the lift coefficient of the aircraft during the taxiing process, CD is the drag coefficient of the aircraft during the taxiing process, m is the mass of the aircraft during the taxiing process, and a is the acceleration of the aircraft during the taxiing process;

[0022] In at least one embodiment of the present application, in step 2, eliminating the influence of the engine data on the test results and calculating the friction coefficient μ between the aircraft and the runway includes:

[0023] The average thrust of the engine is related to:

[0024] 2×F 外 +2×F 内 =4×F

[0025] Subtract the first and second formulas from the third formula to get:

[0026] μ(W-qCL)+qCD=m(a 3 -a 1 -a 2 )

[0027] Substituting the aircraft operating parameters into the above formula, calculate the friction coefficient μ between the aircraft and the runway under the condition of aircraft mass m.

[0028] In at least one embodiment of the present application, step three is also included, selecting other test aircraft mass conditions, obtaining the friction coefficient μ between the aircraft and the runway under different aircraft mass m conditions in the above manner, and realizing the correction of the takeoff performance model.

[0029] A second aspect of the present application provides a runway friction coefficient measurement system, comprising:

[0030] The parameter acquisition module is used to perform acceleration taxiing tests on a 4-engine aircraft according to three engine operation strategies within a set taxiing speed range, and measure the aircraft operation parameters through airborne sensors;

[0031] The friction coefficient calculation module is used to eliminate the influence of engine data on the test results according to a specific aircraft dynamics model and calculate the friction coefficient μ between the aircraft and the runway.

[0032] In at least one embodiment of the present application, in the parameter acquisition module, the taxiing speed range is set to be 10km / h to 30km / h.

[0033] In at least one embodiment of the present application, in the parameter acquisition module, the three engine operation strategies are:

[0034] Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters;

[0035] Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters;

[0036] Start the four inner and outer engines, with the throttle position of the two outer engines at L1 and the throttle position of the two inner engines at L2. The aircraft continues to accelerate and the operating parameters of the aircraft are measured.

[0037] In at least one embodiment of the present application, in the friction coefficient calculation module, the specific aircraft dynamics model is:

[0038] 2×F 外 -μ(W-qCL)-qCD=ma 1

[0039] 2×F 内 -μ(W-qCL)-qCD=ma 2

[0040] 4×F-μ(W-qCL)-qCD=ma 3

[0041] Among them, F 外 is the average thrust of the two outer engines when the throttle position is L1, F 内 is the average thrust of the two inner engines when the throttle position is L2, F is the average thrust of the four engines when the throttle position is L1 and L2, W is the weight of the aircraft during the taxiing process, q is the dynamic pressure of the aircraft during the taxiing process, CL is the lift coefficient of the aircraft during the taxiing process, CD is the drag coefficient of the aircraft during the taxiing process, m is the mass of the aircraft during the taxiing process, and a is the acceleration of the aircraft during the taxiing process.

[0042] In at least one embodiment of the present application, in the friction coefficient calculation module, the influence of engine data on the test results is eliminated, and the friction coefficient μ between the aircraft and the runway is calculated, including:

[0043] The average thrust of the engine is related to:

[0044] 2×F 外 +2×F 内 =4×F

[0045] Subtract the first and second formulas from the third formula to get:

[0046] μ(W-qCL)+qCD=m(a 3 -a 1 -a 2 )

[0047] Substituting the aircraft operating parameters into the above formula, calculate the friction coefficient μ between the aircraft and the runway under the condition of aircraft mass m.

[0048] In at least one embodiment of the present application, a measurement scheme design module is also included for selecting other test aircraft mass conditions, and obtaining the friction coefficient μ between the aircraft and the runway under different aircraft mass conditions m in the above manner to achieve correction of the takeoff performance model.

[0049] The invention has at least the following beneficial technical effects:

[0050] The runway friction coefficient measurement method of the present application obtains relevant data through a low-speed ground taxiing test, which is used to calculate the rolling friction coefficient of the aircraft at an unfamiliar airport, calibrate the takeoff performance model, and obtain a more accurate takeoff performance of the aircraft at the target airport. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is a schematic diagram of the operation strategies of three engines during the test process of one embodiment of the present application;

[0052] Figure 2 It is a schematic diagram of the design of a runway friction coefficient measurement scheme according to one embodiment of the present application. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0054] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0055] The following is combined with Figure 1 to Figure 2 This application is described in further detail.

[0056] The first aspect of the present application provides a method for measuring a runway friction coefficient, comprising:

[0057] Step 1: Within the set taxiing speed range, the four-engine aircraft conducts accelerated taxiing tests according to three engine operation strategies, and measures the aircraft operation parameters through airborne sensors;

[0058] Step 2: According to the specific aircraft dynamics model, eliminate the influence of engine data on the test results and calculate the friction coefficient μ between the aircraft and the runway.

[0059] In the runway friction coefficient measurement method of the present application, in step 1, the taxiing speed range is set to be 10km / h to 30km / h. In such a speed range, the dynamic pressure of the aircraft is small, and the aerodynamic lift and drag are small. The aerodynamic lift and drag are small relative to the thrust of the engine, and the aerodynamic lift and drag are small relative to the friction of the runway, which can reduce the impact of the aerodynamic data on the final result during the test.

[0060] In a preferred embodiment of the present application, Figure 1 As shown in the figure, the three engine operation strategies are:

[0061] ① Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters;

[0062] ② Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters;

[0063] ③ Start the four inner and outer engines, with the throttle position of the two outer engines at L1 and the throttle position of the two inner engines at L2. The aircraft continues to accelerate and the operating parameters of the aircraft are measured.

[0064] In the runway friction coefficient measurement method of the present application, in step 2, the specific aircraft dynamics model is:

[0065] 2×F 外 -μ(W-qCL)-qCD=ma 1

[0066] 2×F 内 -μ(W-qCL)-qCD=ma 2

[0067] 4×F-μ(W-qCL)-qCD=ma 3

[0068] Among them, F 外 is the average thrust of the two outer engines when the throttle position is L1 (unit: N), F 内is the average thrust of the two inner engines when the throttle position is L2 (unit N), F is the average thrust of the four engines when the throttle position is L1 and L2 (unit N), W is the weight of the aircraft during the taxiing process (unit N), q is the dynamic pressure of the aircraft during the taxiing process (unit Pa), CL is the lift coefficient of the aircraft during the taxiing process, CD is the drag coefficient of the aircraft during the taxiing process, m is the mass of the aircraft during the taxiing process, a is the acceleration of the aircraft during the taxiing process (unit m / s 2 ).

[0069] The average thrust of the engine is related to:

[0070] 2×F 外 +2×F 内 =4×F

[0071] Subtract the first and second formulas from the third formula to get:

[0072] μ(W-qCL)+qCD=m(a 3 -a 1 -a 2 )

[0073] Substituting the aircraft operating parameters into the above formula, calculate the friction coefficient μ between the aircraft and the runway under the condition of aircraft mass m.

[0074] The runway friction coefficient measurement method of the present application also includes step 3, selecting other test aircraft mass conditions, obtaining the friction coefficient μ between the aircraft and the runway under different aircraft mass conditions m in the above manner, and realizing the correction of the takeoff performance model. Select multiple mass conditions within the aircraft takeoff mass (weight) range, repeat the above experiment and calculation process, and observe the influence of mass conditions on the friction coefficient μ on the runway.

[0075] In a specific embodiment of the present application, the method for measuring the runway friction coefficient is as follows:

[0076] S1, the test object is a large four-engine aircraft and a runway.

[0077] Set the taxiing weight of the aircraft. According to the takeoff weight range of the aircraft on the runway, set the taxiing weight array of the aircraft during the test. Select one of the values ​​W i As the aircraft taxiing weight.

[0078] Set W i Throttle position L1 under weight conditions. Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters;

[0079] Set W iThrottle position L2 under weight conditions. Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters;

[0080] Start the four inner and outer engines, with the throttle position of the outer engine at L1 and the throttle position of the inner engine at L2, and measure the operating parameters of the aircraft.

[0081] S2, calculate W i The friction coefficient of the track under weight condition μ i Substitute the aircraft operating parameters obtained in step S1 into the formula to calculate the runway friction coefficient μ i .

[0082] μ(W-qCL)+qCD=m(a 3 -a 1 -a 2 )

[0083] S3, update the taxiing weight of the aircraft. Return to step S1 and select the next value W in the taxiing weight array of the aircraft. i+1 As the aircraft taxiing weight.

[0084] Repeat steps S1 to S3 to obtain W i+1 The friction coefficient of the track under weight condition μ i+1 .

[0085] Get the runway friction coefficient μ corresponding to each weight value in the taxi weight array, and observe the effect of weight conditions on the friction coefficient μ on the runway. If the runway friction coefficient μ under different weight conditions is very different, then use the same runway friction coefficient μ to calibrate the takeoff model. If the runway friction coefficient μ under different weight conditions is very different, then use the corresponding runway friction coefficient μ to calibrate the takeoff model.

[0086] The runway friction coefficient measurement method of the present application selects a lower speed range during taxiing to reduce the influence of aerodynamic factors on the results; three engine operation strategies are adopted on large aircraft to reduce the influence of engine factors on the results; the independent variable parameters in the formula for calculating the friction coefficient can all be obtained through sensors on the aircraft without the need for external equipment. Therefore, the method of the present application is simple, accurate, efficient, and highly operable.

[0087] A second aspect of the present application provides a runway friction coefficient measurement system, comprising:

[0088] The parameter acquisition module is used to perform acceleration taxiing tests on a 4-engine aircraft according to three engine operation strategies within a set taxiing speed range, and measure the aircraft operation parameters through airborne sensors;

[0089] The friction coefficient calculation module is used to eliminate the influence of engine data on the test results according to a specific aircraft dynamics model and calculate the friction coefficient μ between the aircraft and the runway.

[0090] In the parameter acquisition module, the taxiing speed range is set to 10km / h to 30km / h.

[0091] In the parameter acquisition module, the three engine operation strategies are:

[0092] Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters;

[0093] Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters;

[0094] Start the four inner and outer engines, with the throttle position of the two outer engines at L1 and the throttle position of the two inner engines at L2. The aircraft continues to accelerate and the operating parameters of the aircraft are measured.

[0095] In the friction coefficient calculation module, the specific aircraft dynamics model is:

[0096] 2×F 外 -μ(W-qCL)-qCD=ma 1

[0097] 2×F 内 -μ(W-qCL)-qCD=ma 2

[0098] 4×F-μ(W-qCL)-qCD=ma 3

[0099] Among them, F 外 is the average thrust of the two outer engines when the throttle position is L1, F 内 is the average thrust of the two inner engines when the throttle position is L2, F is the average thrust of the four engines when the throttle position is L1 and L2, W is the weight of the aircraft during the taxiing process, q is the dynamic pressure of the aircraft during the taxiing process, CL is the lift coefficient of the aircraft during the taxiing process, CD is the drag coefficient of the aircraft during the taxiing process, m is the mass of the aircraft during the taxiing process, and a is the acceleration of the aircraft during the taxiing process;

[0100] In the friction coefficient calculation module, the influence of engine data on the test results is eliminated, and the friction coefficient μ between the aircraft and the runway is calculated, including:

[0101] The average thrust of the engine is related to:

[0102] 2×F 外 +2×F 内 =4×F

[0103] Subtract the first and second formulas from the third formula to get:

[0104] μ(W-qCL)+qCD=m(a 3 -a 1 -a 2 )

[0105] Substituting the aircraft operating parameters into the above formula, calculate the friction coefficient μ between the aircraft and the runway under the condition of aircraft mass m.

[0106] The runway friction coefficient measurement system of the present application also includes a measurement scheme design module for selecting other test aircraft mass conditions, obtaining the friction coefficient μ between the aircraft and the runway under different aircraft mass m conditions in the above manner, and realizing the correction of the takeoff performance model.

[0107] 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 measuring a runway friction coefficient, characterized in that: include: Step 1: Within the set taxiing speed range, the four-engine aircraft conducts accelerated taxiing tests according to three engine operation strategies, and measures the aircraft operation parameters through airborne sensors; Step 2: According to the specific aircraft dynamics model, eliminate the influence of engine data on the test results and calculate the friction coefficient μ between the aircraft and the runway.

2. The method for measuring the runway friction coefficient according to claim 1, characterized in that: In step 1, the sliding speed is set in the range of 10km / h to 30km / h.

3. The method for measuring the runway friction coefficient according to claim 2, characterized in that: In step 1, the three engine operation strategies are: Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters; Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters; The four inner and outer engines are started, with the throttle position of the two outer engines at L1 and the throttle position of the two inner engines at L2. The aircraft continues to accelerate and the operating parameters of the aircraft are measured.

4. The method for measuring the runway friction coefficient according to claim 3, characterized in that: In step 2, the specific aircraft dynamics model is: 2×F 外 -μ(W-qCL)-qCD=ma1 2×F 内 -μ(W-qCL)-qCD=ma2 4×F-μ(W-qCL)-qCD=ma3 Among them, F 外 is the average thrust of the two outer engines when the throttle position is L1, F 内 is the average thrust of the two inner engines when the throttle position is L2, F is the average thrust of the four engines when the throttle position is L1 and L2, W is the weight of the aircraft during the taxiing process, q is the dynamic pressure of the aircraft during the taxiing process, CL is the lift coefficient of the aircraft during the taxiing process, CD is the drag coefficient of the aircraft during the taxiing process, m is the mass of the aircraft during the taxiing process, and a is the acceleration of the aircraft during the taxiing process.

5. The method for measuring the runway friction coefficient according to claim 4, characterized in that: In step 2, the influence of engine data on the test results is eliminated, and the friction coefficient μ between the aircraft and the runway is calculated, including: The average thrust of the engine is related to: 2×F 外 +2×F 内 =4×F Subtract the first and second formulas from the third formula to get: μ(W-qCL)+qCD=m(a3-a1-a2) Substituting the aircraft operating parameters into the above formula, calculate the friction coefficient μ between the aircraft and the runway under the condition of aircraft mass m.

6. The method for measuring the runway friction coefficient according to claim 5, characterized in that: The method also includes step 3, selecting other test aircraft mass conditions, obtaining the friction coefficient μ between the aircraft and the runway under different aircraft mass m conditions in the above manner, and realizing the correction of the takeoff performance model.

7. A runway friction coefficient measurement system, characterized in that: include: The parameter acquisition module is used to perform accelerated taxiing tests on a 4-engine aircraft according to three engine operation strategies within a set taxiing speed range, and measure the aircraft operation parameters through airborne sensors; The friction coefficient calculation module is used to eliminate the influence of engine data on the test results according to a specific aircraft dynamics model and calculate the friction coefficient μ between the aircraft and the runway.

8. The runway friction coefficient measurement system according to claim 7, characterized in that: In the parameter acquisition module, the taxiing speed range is set to 10km / h to 30km / h.

9. The runway friction coefficient measurement system according to claim 8, characterized in that: In the parameter acquisition module, the three engine operation strategies are: Start only the two outer engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L1, and measure the aircraft operating parameters; Start only the two inner engines, increase the throttle until the aircraft slowly accelerates, record the throttle position as L2, and measure the aircraft operating parameters; Start the four inner and outer engines, with the throttle position of the two outer engines at L1 and the throttle position of the two inner engines at L2. The aircraft continues to accelerate and the operating parameters of the aircraft are measured.

10. The runway friction coefficient measurement system according to claim 9, characterized in that: In the friction coefficient calculation module, the specific aircraft dynamics model is: 2×F 外 -μ(W-qCL)-qCD=ma1 2×F 内 -μ(W-qCL)-qCD=ma2 4×F-μ(W-qCL)-qCD=ma3 Among them, F 外 is the average thrust of the two outer engines when the throttle position is L1, F 内 is the average thrust of the two inner engines when the throttle position is L2, F is the average thrust of the four engines when the throttle position is L1 and L2, W is the weight of the aircraft during the taxiing process, q is the dynamic pressure of the aircraft during the taxiing process, CL is the lift coefficient of the aircraft during the taxiing process, CD is the drag coefficient of the aircraft during the taxiing process, m is the mass of the aircraft during the taxiing process, and a is the acceleration of the aircraft during the taxiing process.

11. The runway friction coefficient measurement system according to claim 10, characterized in that: In the friction coefficient calculation module, the influence of engine data on the test results is eliminated, and the friction coefficient μ between the aircraft and the runway is calculated, including: The average thrust of the engine is related to: 2×F 外 +2×F 内 =4×F Subtract the first and second formulas from the third formula to get: μ(W-qCL)+qCD=m(a3-a1-a2) Substituting the aircraft operating parameters into the above formula, calculate the friction coefficient μ between the aircraft and the runway under the condition of aircraft mass m.

12. The runway friction coefficient measurement system according to claim 11, characterized in that: It also includes a measurement scheme design module for selecting other test aircraft mass conditions, obtaining the friction coefficient μ between the aircraft and the runway under different aircraft mass conditions m in the above manner, and realizing the correction of the take-off performance model.

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