Small bypass ratio turbofan engine clearance gap quantification analysis and evaluation method

Abstract

The application belongs to the field of aero-engine design, and is a small-bypass-ratio turbofan engine gap quantitative analysis and evaluation method. By establishing three-dimensional engine coordinate system and aircraft coordinate system respectively, the coordinates of each point of the aircraft and the engine can be accurately determined. Then, by determining the key parameters of gap evaluation and their influencing factors, the main influencing factors of the aircraft-engine gap are more completely and clearly defined, which can avoid the omission of key factors in the evaluation process and obtain more engineering practical evaluation results. Through the decomposition of the factors affecting the aircraft-engine gap and the coordinate definition and transformation of the specified parts, the quantitative evaluation of the gap can be realized, which provides a method for the digital application of gap evaluation. The amount of calculation and evaluation data obtained will be much higher than that obtained by the existing evaluation method, which realizes more complete, accurate and efficient evaluation of the aircraft-engine gap, and improves the quality and efficiency of the aircraft-engine collaborative design.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aero-engine design, and particularly relates to a small-bypass-ratio turbofan engine fly-by clearance quantification analysis and evaluation method. BACKGROUND

[0002] "Fly-by clearance analysis and evaluation" is an essential technical activity in the process of fly-by collaborative design and technical coordination, which is crucial for realizing the structural matching between the aircraft and the engine, ensuring the installation of the engine on the aircraft and the fly-by safety during the flight of the aircraft. For a large-thrust military small-bypass-ratio turbofan engine, on the one hand, with the increase of the engine thrust, the engine inlet diameter gradually increases; on the other hand, the aircraft needs better aerodynamic shape and smaller wind area in order to obtain better flight performance; in addition, with the increase of the combat demand of the new generation of aircraft and engine, the system function of the aircraft and the engine is more complex, which also means that the number of engine system accessories installed outside the engine and the number of aircraft related system accessories installed inside the aircraft engine compartment are more, and the function is more integrated. The above requirements and conditions will greatly increase the difficulty of clearance control between the engine and the fly-by after the engine is installed, and the requirements for fly-by clearance analysis and evaluation are also correspondingly increased.

[0003] There are two ways for existing fly-by clearance analysis and evaluation:

[0004] 1) Sectioned contour line (two-dimensional) method

[0005] The evaluation and analysis method of this method is mainly to set a plurality of cross sections perpendicular to the center axis of the engine along the axial direction of the engine from front to back (usually about 10-20 cross sections), divide the engine into a plurality of sections along the axial direction through these cross sections, then project the engine case, accessories, pipelines and their corresponding connectors and fasteners outside each section onto the corresponding plane, and then draw a contour line (two-dimensional graphic mode) that can envelope these components on the plane. Provide the contour line drawn by each section to the aircraft side, and the aircraft side evaluates whether the aircraft components at the corresponding axial position on the aircraft engine compartment interfere with the engine or the clearance is too small according to the position of the engine sections.

[0006] The method evaluation process is shown in Figure 1 and Figure 2 .

[0007] 2) Electronic prototype (three-dimensional) method

[0008] The evaluation and analysis method of this mode mainly provides the three-dimensional model of the external structure of the engine (i.e. the electronic prototype) directly to the aircraft side, the aircraft side assembles the external electronic prototype of the engine and the three-dimensional model of the aircraft engine compartment according to the specified position in the three-dimensional design software, and then identifies the positions of the interference or small gap between the aircraft and the engine in the three-dimensional model by manual method, and measures the gap of the small gap position between the aircraft and the engine by manual method.

[0009] At present, the above two methods are the two technical methods commonly used in China for analyzing and evaluating the gap between the aircraft and the engine. These two methods have the following deficiencies in technology and efficiency:

[0010] 1. Only the evaluation of the non-working state of the aircraft and the engine can be realized, and the comprehensiveness of the evaluation is insufficient.

[0011] The two evaluation methods introduced above can only realize the evaluation of the gap between the aircraft and the engine in the cold state assembly (non-working state), and the gap between the aircraft and the engine in the working state cannot be evaluated. Compared with the cold state assembly condition, during the working operation of the aircraft and the engine, many dimensions of the aircraft and the engine will change due to the influence of factors such as thermal deformation, flight maneuver load, and load interaction between the aircraft and the engine. The changed gap between the aircraft and the engine may be quite different from the gap evaluated under the cold state condition.

[0012] 2. The evaluation and analysis process cannot be digitized, and only relies on manual judgment, which has deficiencies in precision, accuracy and evaluation efficiency.

[0013] Although the above two methods use two-dimensional (such as CAD) or three-dimensional (such as UG, CATIA, CAXA) drawing software, in essence, only the evaluation objects (aircraft and engine) are digitized to form digital drawings or models, and the evaluation process is not digitized. The actual evaluation process still relies on manual identification and measurement to analyze and evaluate the positions of interference or small gap between the aircraft and the engine. The fundamental reason why the evaluation process cannot be digitized is that the positions that need to be evaluated in the evaluation object cannot be quantitatively analyzed, i.e. the spatial position information of the key parts of the aircraft and the engine and the quantitative decomposition of the main factors affecting the position information are not realized.

[0014] The effects of the evaluation and analysis process not being digitized are as follows:

[0015] 1) Lack of precision. Since the evaluation process is realized by manual identification and measurement, the number of key parts evaluated is limited, usually only to the order of tens of key parts; and since the identification of key parts is realized by manual method, there may be omissions;

[0016] 2) Accuracy is insufficient. Since the evaluation process is achieved by manual identification and measurement, the evaluation process is affected by human subjective factors and actual operation process, and there is certain uncertainty in the accuracy of the gap evaluation, and the accuracy of the evaluation may deviate due to different executors;

[0017] 3) Evaluation efficiency is insufficient. Since manual identification and judgment are needed, the evaluation efficiency is limited. Generally, for electronic prototype (three-dimensional) mode, under the condition that the assembly of the fly-by model is completed in the drawing software, the design personnel with certain engineering experience generally need to spend several to tens of hours to evaluate the interference and gap; for segmented contour line (two-dimensional) mode, more time is spent. In addition, for the case where multiple iterations are needed between fly-by, each iteration needs to spend the above time, and with the increase of the number of iterations, the time and labor cost are also increased substantially.

[0018] Therefore, how to more simply and effectively evaluate the fly-by gap is a problem to be solved. SUMMARY

[0019] The purpose of the present application is to provide a small-bypass-ratio turbofan engine fly-by gap quantification analysis and evaluation method to solve the problem of insufficient comprehensiveness, fineness and accuracy caused by relying mainly on manual identification for fly-by gap evaluation in the prior art.

[0020] The technical solution of the present application is: a small-bypass-ratio turbofan engine fly-by gap quantification analysis and evaluation method, comprising: defining three-dimensional engine coordinate system and aircraft coordinate system, determining the conversion relationship of the fly-by coordinate system; determining the key parameters of gap evaluation and their influencing factors, collecting or calculating the numerical values of each influencing factor, and calculating the minimum gap of a part between fly-by; evaluating and evaluating the fly-by gap according to the minimum gap of the fly-by.

[0021] Preferably, the key parameter is the cumulative change amount Σ of the fly-by gap of a part, and the influencing factors of the cumulative change amount Σ of the fly-by gap of a part are 9, then the relationship between the cumulative change amount Σ of the fly-by gap of a part and the influencing factors is:

[0022] Σ = Δ EM + Δ AM + Δ AF + Δ EF + Δ EH + Δ AH + Δ EP + Δ axial + Δ model

[0023] Wherein, ΔEM is the manufacturing tolerance of the engine in the radial direction; ΔAM is the manufacturing tolerance of the aircraft in the engine radial direction; Δ AF is the displacement and deformation of the aircraft component in the engine radial direction due to the aircraft maneuver load; Δ EF is the displacement and deformation of the engine component in the engine radial direction due to the flight maneuver load; Δ EH is the thermal deformation of the engine in the engine radial direction; Δ AH is the thermal deformation of the aircraft in the engine radial direction; Δ EP is the expansion deformation of the engine in the engine radial direction due to the internal pressure; Δ axial is the change of the radial clearance of a part due to the axial movement of the engine relative to the aircraft; Δ model is the inaccuracy of the model.

[0024] Preferably, the Δ AM and Δ EM are calculated by using the extreme value method, and the specific calculation method is: the limit value of the manufacturing tolerance is accumulated to obtain the manufacturing tolerance under the limit condition.

[0025] Preferably, the Δ AM and Δ EM are calculated by using the probability method, and the specific calculation method is: based on the physical processing size statistical sample, the processing tolerance distribution probability of the specific component is estimated according to the actual processing level of the manufacturing unit, and the manufacturing tolerance is obtained by accumulating the probability of each component tolerance.

[0026] Preferably, when evaluating the displacement change amount of a part of the engine due to pressure, only the expansion deformation of the main engine case of the engine where the part is located due to the internal pressure is considered, and the expansion deformation of the components such as accessories and pipelines outside the engine at the part due to the internal pressure is ignored.

[0027] Preferably, the calculation method of the minimum value of the clearance of a part between the aircraft and the engine is:

[0028] The nominal value C0 of the clearance between the aircraft and the engine at the part is obtained, and then the minimum value C of the clearance between the aircraft and the engine at the part is calculated. min is:

[0029] C min =C0-∑.

[0030] Preferably, the evaluation and assessment method of the clearance between the aircraft and the engine is: the minimum value C req of the clearance between the aircraft and the engine at the part required by the design requirement is obtained, and then it is judged: if C min >0, and C min >C req , it is indicated that the clearance between the aircraft and the engine is sufficient, and meets the design specified clearance value between the aircraft and the engine; if Cmin > 0, and 0 < C min < C req , it is indicated that the gap between the parts will not cause the hardware of the engine to collide, even if the gap does not conform to the theoretical gap requirement between the rotors; if C min < 0, and the development of the engine is in the initial flight stage, measures should be taken to alleviate the situation and strengthen monitoring in flight tests; if C min < 0, and the development of the engine is in the initial service stage, the situation of C min < 0 should be avoided.

[0031] Preferably, the definition method of the engine coordinate system is: determining the position of the origin of the engine coordinate system as the intersection of the main installation plane of the engine and the center axis of the engine; determining the X E axis of the engine coordinate system as positive along the forward direction of the engine; the Y E axis of the engine coordinate system as positive along the right direction of the engine; and the Z E axis of the engine coordinate system as positive along the upward direction of the engine; and the definition method of the aircraft coordinate system is: determining the position of the origin of the aircraft coordinate system as the design center of gravity of the aircraft; determining the X A axis of the aircraft coordinate system as positive along the direction of the air flow when the aircraft is in horizontal flight; the Y A axis of the aircraft coordinate system as positive along the right direction of the aircraft; and the Z A axis of the aircraft coordinate system as positive along the upward direction of the aircraft.

[0032] Preferably, the conversion method of the aircraft and engine coordinate systems is: X A = X E + X AE ; Y A = Y E + Y AE ; and Z A = Z E + Z AE ; wherein X AE is the straight-line distance between X E and X A , Y AE is the straight-line distance between Y E and Y A , and Z AE is the straight-line distance between Z E and Z A .

[0033] The small-cant low bypass ratio turbofan engine clearance quantitative analysis and evaluation method provided by the application, by establishing three-dimensional engine coordinate system and aircraft coordinate system, the coordinates of each point of the aircraft and the engine can be accurately determined, and then by determining the clearance evaluation key parameters and their influencing factors, the main influencing factors of the aircraft-engine clearance are more completely and clearly defined, and the application scope and scene of each influencing factor are accurately defined and explained, each influencing factor can be accurately obtained through coordinates, the minimum clearance of the aircraft-engine is obtained through calculation, by using complete data calculation, the omission of key factors can be avoided in the evaluation process, and more close to the engineering actual evaluation results are obtained; through the decomposition of the factors affecting the aircraft-engine clearance and the coordinate definition and transformation of the specified parts, the quantitative evaluation of the clearance can be realized, and the method for the digital application of the clearance evaluation is provided. Based on the method as the bottom logic and foundation, by compiling the corresponding calculation program or developing on the basis of the existing three-dimensional mapping model, the clearance calculation and evaluation of a large number of specified positions between the aircraft-engine can be realized, the amount of calculation and evaluation data obtained will be much higher than that obtained by the existing evaluation method, since the manual observation and measurement steps of the aircraft-engine clearance are reduced, a large amount of time is saved, the more complete, accurate and efficient evaluation of the aircraft-engine clearance is realized, and the quality and efficiency of the aircraft-engine collaborative design are improved. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions provided by the application, the following will briefly introduce the drawings. Obviously, the drawings described below are only some embodiments of the application.

[0035] Figure 1 The schematic diagram of the segmented contour line evaluation method in the background art;

[0036] Figure 2 The schematic diagram of the segmented contour line profile shape in the background art;

[0037] Figure 3 The schematic diagram of the overall process of the application;

[0038] Figure 4 The schematic diagram of the engine coordinate system of the application;

[0039] Figure 5 The schematic diagram of the aircraft coordinate system of the application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the application clearer, the technical solutions in the embodiments of the application will be described in more detail below with reference to the drawings in the embodiments of the application.

[0041] A quantitative analysis and evaluation method for the jet engine clearance of a low-bypass turbofan engine is proposed. This method establishes a three-dimensional coordinate system and identifies all factors affecting the jet engine clearance. The specific data of each influencing factor is found directly by calculation or direct search. The jet engine clearance is calculated using complete data, which is a non-manual identification method.

[0042] like Figure 3 As shown, the specific methods include:

[0043] Step S100: Define the three-dimensional engine coordinate system and aircraft coordinate system, and determine the transformation relationship between the engine and aircraft coordinate systems;

[0044] like Figure 4 As shown, the method for defining the engine coordinate system is as follows:

[0045] 1) Determine the origin of the engine coordinate system, which is the intersection of the main mounting plane of the engine and the central axis of the engine; the origin and intersection positions are determined according to the specific engine model, and there are differences between different engines;

[0046] 2) Determine the X coordinate of the engine based on the right-hand rule. E The direction of rotation backwards along the engine's heading is positive; Y E The direction to the right along the engine's horizontal axis is positive; Z E The vertical direction upwards along the engine is considered positive.

[0047] like Figure 5 As shown, the method for defining the aircraft coordinate system is as follows:

[0048] 1) Determine the location of the origin of the aircraft coordinate system, which is the design center of gravity of the aircraft; the location of the origin and the center of gravity are determined specifically according to the specific aircraft model, and there are differences between different aircraft.

[0049] 2) Determine the X coordinate of the aircraft coordinate system based on the right-hand rule. A The direction of the airflow when the aircraft is flying horizontally is taken as positive; Y A Z is positive when the plane is horizontally to the right. A The vertical direction of the aircraft is considered positive.

[0050] The method for transforming the aircraft and engine coordinate systems is as follows:

[0051] X A =X E +X AE ;

[0052] Y A =Y E +Y AE ;

[0053] Z A =ZE +Z AE ;

[0054] wherein X AE is the linear distance between X E and X A , Y AE is the linear distance between Y E and Y A , and Z AE is the linear distance between Z E and Z A .

[0055] By establishing the aircraft coordinate system and the engine coordinate system respectively, and establishing the connection relationship between the two, the coordinates of any point on the aircraft can be accurately positioned through the engine coordinate system, and the coordinates of any point on the engine can be accurately positioned through the aircraft coordinate system.

[0056] In step S200, the gap evaluation key parameters and their influencing factors are determined, the values of each influencing factor are collected or calculated, and the minimum gap of a part between the aircraft and the engine is calculated.

[0057] The key parameter is determined as the cumulative change amount Σ of the gap between the aircraft and the engine, and Σ is the calculated evaluation value. The cumulative change amount includes the cumulative change amount of the gap between the aircraft and the engine in the non-working state, and the cumulative change amount of the gap in the working state.

[0058] The cumulative change amount is characterized by the X, Y, and Z coordinate directions of the aircraft and the engine. For the convenience of description, only the factors affecting Σ are described in the following description of the cumulative change amount Σ, without specifying a specific coordinate direction.

[0059] In addition, it should be noted that: in theory, the gap change between the aircraft and the engine has both radial direction change (reflected in the coordinate system as the change of the values in the Y and Z directions) and axial direction change (reflected in the coordinate system as the change of the value in the X direction); but in engineering, the main influence on the gap change between the aircraft and the engine is the change of the aircraft and engine components in the radial direction, so the evaluation of the gap change between the aircraft and the engine is actually mainly to analyze and evaluate the gap change between the aircraft and the engine in the radial direction of the engine, and the axial gap change between the aircraft and the engine is considered as a secondary factor.

[0060] In the analysis and evaluation of the gap change between the aircraft and the engine, the axial misalignment of the components between the aircraft and the engine is only considered as a part of the influencing factor of the radial gap change.

[0061] The cumulative change amount Σ of the gap between the aircraft and the engine at a certain part is mainly composed of the following 9 influencing factors, and the relationship between the cumulative change amount Σ of the gap between the aircraft and the engine at the certain part and the influencing factors is:

[0062] Σ=Δ EM +Δ AM +Δ AF +Δ EF +Δ EH +Δ AH +Δ EP +Δ axial +Δ model (1)

[0063] The variables in the formula are explained below:

[0064] ①Δ EM Manufacturing tolerances of the engine in the radial direction;

[0065] ②Δ AM Manufacturing tolerances of the aircraft in the radial direction of the engine;

[0066] Note: For factors ① and ②, different evaluation methods can be used to assess the manufacturing tolerances of aircraft and engines:

[0067] Extreme value method: This method accumulates the extreme values ​​of manufacturing tolerances (upper and lower deviations) to obtain the extreme manufacturing tolerance. This method is relatively simple to calculate and yields a conservative tolerance assessment, but it deviates significantly from actual manufacturing conditions. This method can be used when the actual manufacturing capabilities of aircraft and engine manufacturers are insufficiently assessed, or when the accumulated sample size of actual manufacturing data is small.

[0068] Probabilistic Method: This method takes into account the actual processing level and capabilities of the manufacturing unit. The tolerance assessment results obtained using this method are closer to the actual processing situation and better reflect the true processing level of the manufacturing unit. However, this method requires a relatively sufficient statistical sample of actual processed dimensions. This method should be used when there is a relatively accurate understanding of the actual processing capabilities of a specific manufacturing unit. The specific calculation method is as follows: Based on a relatively sufficient statistical sample of actual processed dimensions, estimate the probability distribution of processing tolerances for specific components according to the actual processing level of the manufacturing unit, and then accumulate the tolerances of each component using this probability to obtain the final manufacturing tolerance.

[0069] ③Δ AF Displacement and deformation of aircraft components in the radial direction of the engine due to flight maneuver loads;

[0070] ④Δ EF Displacement and deformation of engine components in the radial direction due to flight maneuver loads;

[0071] ⑤Δ EH Thermal deformation of the engine in the radial direction;

[0072] ⑥Δ AH: the thermal deformation of the engine in the radial direction of the engine;

[0073] Note: for the ⑥th factor, it can be selected according to the specific use conditions of the aircraft:

[0074] Generally, for aircraft with low flight speed (such as ordinary fighters), the change of the clearance between the engine and the aircraft is mainly caused by the thermal deformation of the engine, so from the perspective of engineering simplification, the thermal deformation of the aircraft can be ignored;

[0075] For aircraft with high flight speed (such as hypersonic aircraft flying at high Mach number for a long time), the aerodynamic heating effect of the airflow on the aircraft body cannot be ignored, and this factor needs to be considered.

[0076] ⑦Δ EP : the radial expansion deformation of the engine caused by the internal pressure of the engine;

[0077] Note: for the ⑦th factor, in theory, any pressure vessel will deform when subjected to the pressure of the internal medium, but from the perspective of engineering practice, the main deformation causing the radial expansion deformation of the engine is the expansion deformation of the main casing of the engine caused by the internal airflow pressure. Therefore, when evaluating the displacement change caused by the pressure of a certain part of the engine, only the expansion deformation of the main casing of the engine caused by the internal pressure of the part is considered, and the expansion deformation of the external components such as accessories and pipelines caused by the internal pressure of the part can be ignored.

[0078] ⑧Δ axial : the change of the radial clearance caused by the axial movement of the engine relative to the aircraft;

[0079] ⑨Δ model : the inaccuracy of the model.

[0080] Note: for the ⑨th factor, it is suitable for flexible components used on the engine and the aircraft. Compared with rigid components such as casings and accessories, some flexible components (such as cables, hoses, and elastic components) cannot accurately reflect the shape and position of the actual object in space, so when evaluating the clearance, the change of the clearance caused by the inaccuracy of the model should be considered.

[0081] The calculation method of the minimum value of the clearance between any part of the engine and the aircraft is as follows:

[0082] Obtain the nominal value C0 of the clearance between the engine and the aircraft at the part, that is, the value of the clearance between the engine and the aircraft at the part calculated by the theoretical model of the engine.

[0083] Under the working state of the engine, the minimum value C of the clearance between the engine and the aircraft at the part is calculatedmin For:

[0084] C min = C0-∑ (2).

[0085] Through formula (1), the specific numerical calculation method at any gap between the flywheel is found, and through collecting or calculating the specific value of each influencing factor, the flywheel gap can be accurately calculated.

[0086] Step S300, according to the minimum value of the flywheel gap, the flywheel gap is evaluated and evaluated.

[0087] The specific method is:

[0088] Obtain the minimum value of the flywheel gap C req of the design requirement, that is, the specified theoretical gap between the flywheels. When the flywheel gap calculation is completed, C min is obtained, and C min obtained by calculation is evaluated:

[0089] 1) If C min > 0, it is divided into two cases:

[0090] · When C min > C req , it means that the gap between the flywheels is sufficient and meets the design specified flywheel gap value, which is acceptable to both flywheels;

[0091] · When 0 < C min < C req , it means that although the gap between these parts of the flywheels does not meet the theoretical gap requirement between the flywheels, after considering the deformation under various engine conditions, there will be no flywheel hardware collision, and in this case, both flywheels are acceptable.

[0092] 2) If C min < 0, it means that from the theoretical analysis and model calculation point of view, these points may produce flywheel hardware collision within the envelope, but it cannot be determined whether the actual installation will indeed collide. Therefore, at different stages of engine development, for C min < 0, there are two processing methods:

[0093] · In the initial flight stage, for C min < 0, measures need to be taken to alleviate and strengthen monitoring in flight test;

[0094] · In the initial service stage, C min < 0 should be avoided.

[0095] By establishing three-dimensional engine coordinate system and aircraft coordinate system respectively, the coordinates of each point of the aircraft and engine can be accurately determined, and then by determining the clearance evaluation key parameters and their influencing factors, the main influencing factors of the engine-aircraft clearance are more complete and more clear, and the scope and scene of each influencing factor are accurately defined and explained, each influencing factor can be accurately obtained by coordinates, the minimum clearance of the engine-airplane can be obtained by calculation, by using complete data calculation, the omission of key factors can be avoided in the evaluation process, and more close to the engineering actual evaluation results can be obtained; through the decomposition of the factors affecting the engine-aircraft clearance and the coordinate definition and transformation of the specified parts, the quantitative evaluation of the clearance can be realized, and the method for the digital application of the clearance evaluation is provided. Based on the method as the bottom logic and foundation, by compiling the corresponding calculation program or developing on the basis of the existing three-dimensional mapping model, the clearance calculation and evaluation of a large number of specified positions between the engine and the aircraft can be realized, the amount of calculation and evaluation data obtained will be much higher than that obtained by the existing evaluation method, since the manual observation and measurement steps of the engine-aircraft clearance are reduced, a large amount of time is saved, the more complete, accurate and efficient evaluation of the engine-aircraft clearance is realized, and the quality and efficiency of the engine-aircraft collaborative design are improved.

[0096] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any skilled person in the art can easily think of changes or replacements within the technical range disclosed in the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for small bypass ratio turbofan engine fan-to- case clearance quantification analysis and evaluation, characterized in that, The application relates to an engine clearance evaluation method. The method comprises the following steps: Defining a three-dimensional engine coordinate system and an airplane coordinate system, and determining the conversion relationship of the engine coordinate system and the airplane coordinate system; Determining key parameters of clearance evaluation and influence factors, collecting or calculating the values of the influence factors, and calculating the minimum clearance of a part between the engine and the airplane; Evaluating and assessing the clearance between the engine and the airplane according to the minimum clearance; Σ = Δ EM + Δ AM + Δ AF + Δ EF + Δ EH + Δ AH + Δ EP + Δ axial + Δ model where Δ EM is the manufacturing tolerance of the engine in the radial direction; Δ AM is the manufacturing tolerance of the aircraft in the radial direction of the engine; Δ AF displacement and deformation of the aircraft component in the radial direction of the engine due to the aircraft maneuver load; Delta EF displacement and deformation of the engine components in the radial direction of the engine due to flight maneuver loads; Δ EH for thermal deformation of the engine in the engine radial direction; Δ AH for thermal deformations of the aircraft in the radial direction of the engine; Δ EP for expansion deformation of the engine in the radial direction of the engine due to internal pressure; Δ axial is the amount of change in the radial clearance for a portion due to the axial movement of the engine relative to the aircraft; Δ model for the inaccuracy of the model; The key parameter is the cumulative variation amount Sigma of the clearance between the engine and the airplane at a part, the influence factors of the cumulative variation amount Sigma are nine, and the relationship between the cumulative variation amount Sigma and the influence factors is: The nominal value C0 of the flying clearance of the part is obtained, and then the minimum value C of the flying clearance is calculated min is: C min = C0-∑; The calculation method of the minimum clearance of a part between the engine and the airplane is: The minimum value C of the gap between the parts of the design requirement is acquired req A judgment is made: If C min > 0, and C min > C req , it means that the gap between the flying objects is sufficient and meets the design specified gap value between the flying objects. If C min > 0 and 0 < C min < C req , it means that the gap of these parts between the rotors does not meet the theoretical gap requirement between the rotors, but after considering the deformation under various working conditions of the engine, the rotor hardware will not be collided. If C min <0, and the engine development is in the initial flight phase, mitigation measures need to be taken in flight tests and monitoring needs to be enhanced; If C min <0, and the engine is in the initial service stage, the situation C min <0 should be avoided.

2. The small-bypass-ratio turbofan engine clearance quantification analysis and assessment method of claim 1, wherein The Δ AM and Δ EM The calculation is performed using the extremum method, and the specific calculation method is as follows: The evaluation and assessment method of the clearance between the engine and the airplane is:

3. The small-bypass-ratio turbofan engine clearance quantification analysis and assessment method of claim 1, wherein: The Δ AM and Δ EM The probability method is used for calculation, and the specific calculation method is: based on the physical processing size statistical sample, the processing tolerance distribution probability of the specific component is estimated according to the actual processing level of the manufacturing unit, and the manufacturing tolerance is obtained by accumulating the probability of each component tolerance.

4. The small-bypass-ratio turbofan engine clearance quantification analysis and assessment method of claim 1, wherein: The limit value of the manufacturing tolerance is accumulated to obtain the manufacturing tolerance under the limit condition.

5. The small-bypass-ratio turbofan engine clearance quantification analysis and assessment method of claim 1, wherein When the displacement variation amount of a part of the engine caused by pressure is evaluated, only the expansion deformation of the main engine casing of the part caused by the internal pressure is considered, and the expansion deformation of the components, such as accessories and pipelines, outside the engine caused by the internal pressure is ignored. The definition method of the engine coordinate system is: X is positive along the engine coordinate with the right-hand rule E Y is positive along the engine coordinate with the right-hand rule E Z is positive along the engine coordinate with the right-hand rule E Z is positive along the engine coordinate with the right-hand rule The position of the origin of the engine coordinate system is determined as the intersection point of the main installation plane of the engine and the central axis of the engine; The definition method of the airplane coordinate system is: The X axis of the aircraft coordinate system is determined based on the right-hand rule A is positive along the direction of the air flow when the aircraft is flying horizontally; Y A is positive along the right direction of the aircraft; and Z A is positive along the vertical upward direction of the aircraft.

6. The low bypass ratio turbofan engine clearance quantification analysis and evaluation method as recited in claim 5, characterized in that, The position of the origin of the airplane coordinate system is determined as the design center of gravity of the airplane; The conversion method of the airplane and engine coordinate systems is: X A = X E + X AE ; Y A = Y E + Y AE ; Z A = Z E + Z AE ; wherein X AE is the straight-line distance between X E and X A Y AE is the straight-line distance between Y E and Y A Z AE is the straight-line distance between Z E and Z A .

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