Working condition load calculation method of turboprop aircraft engine hanging structure

Abstract

The invention provides a working condition load calculation method of a turboprop aircraft engine hanging structure. The method comprises the following steps: S1, according to basic performance parameters of an engine, obtaining tensile force, torque, engine rotating speed, propeller rotating speed, engine rotor and propeller blade rotational inertia, engine fault stop time and maximum acceleration under rated and take-off power of the engine; s2, according to the typical maneuvering envelope of the aircraft, flight load coefficients of state points A, A1 and D1 are obtained, and the design maneuvering speed VA under 2.5 g overload and the design maneuvering speed VA1 and the design diving speed VD1 under the 1g level flight state are correspondingly obtained; s3, calculating the 1P load of the engine according to the attack angle and sideslip angle parameters of the aircraft in the maneuvering state; and S4, according to the CCAR 25.361, the CCAR 25.363, the CCAR 25.371 and the CCAR 25.561, the loads under the various working conditions are calculated and combined. According to the invention, the possibility of not omitting the boundary is reduced while the number of calculated working conditions is reduced.

Description

Technical Field

[0001] This invention belongs to the technical field of working condition load combination principles and calculation technology of turboprop aircraft engine pylon structure, specifically relating to a method for calculating the working condition load of turboprop aircraft engine pylon structure. Background Technology

[0002] As a core load-bearing component connecting the airframe and engine, the completeness of the aircraft engine pylon structure's operating conditions and loads directly affects aircraft flight safety and structural integrity. The aircraft engine pylon structure must withstand corresponding types of loads under various operating scenarios, such as engine thrust, torque, inertial loads, gyroscopic loads, and other loads. Currently, domestic calculations of the operating conditions and loads for aircraft pylon structures are based on airworthiness regulations; however, the combinations of operating conditions and calculation items are relatively simple, and there are common problems such as missing operating conditions or incomplete load calculation items. Summary of the Invention

[0003] The purpose of this invention is to provide a method for calculating the operating loads of a turboprop aircraft engine mounting structure. This invention reduces the number of operating conditions to be calculated without overlooking potential boundary conditions.

[0004] Technical solution. A method for calculating the operating load of a turboprop aircraft engine mounting structure, comprising: S1. Based on the engine's basic performance parameters, obtain the thrust, torque, engine speed, propeller speed, engine rotor and propeller blade moment of inertia, engine failure downtime, and maximum acceleration at the engine's rated and takeoff power. S2. Based on the typical maneuver envelope of the aircraft, the flight load coefficients at state points A, A1, and D1 are obtained, corresponding to the design maneuver speed V under a 2.5g overload. A Design speed V in 1g level flight condition A1 Design dive speed V D1 ; S3. Calculate the engine 1P load based on the angle of attack and sideslip angle parameters of the aircraft under maneuvering conditions; S4. Calculate and combine loads under various working conditions based on CCAR25.361, CCAR25.363, CCAR25.371 and CCAR25.561.

[0005] In the aforementioned principle and calculation method for the load combination of the engine suspension structure, in S4, the process of combining the load conditions and calculation items for CCAR25.361(a)(1) is as follows: From all V HA Six operating conditions were selected from the 2.5g motor balance situation and compared with T 起飞 1.25M 起飞 and 0.75F ZNCombination; the 6 operating conditions are: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP Minimum; The process of combining operating conditions and calculation items for CCAR25.361(a)(2) is as follows: From all V HA Six working conditions identical to those in 25.361(a)(1) were selected from the 2.5g dynamic balance conditions and compared with T. 连续 1.25M 连续 and F ZN combination; The process of combining the operating conditions and calculation items for CCAR25.361(a)(3) is as follows: V A and V C Six operating conditions were selected based on the 1g level flight condition, and compared with T 起飞 1.25M 起飞 and 0.75F ZN Combination; V A or V C The six operating conditions are: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP The minimum, with a total of 12 operating conditions.

[0006] In the aforementioned principle and calculation method for the load combination of the engine suspension structure, in S4, the process of combining the load conditions and calculation items for CCAR25.361(b)(1) is as follows: For all V A and V C Four operating conditions were selected from the 1g level flight conditions and compared with M. 停车 and F Z1 Combination; the four operating conditions are: V A or V C At that time, F ZA Maximum, F ZA Minimum; The process of combining operating conditions and calculation items for CCAR25.361(b)(2) is as follows: For all V A ~V D The 1g level flight condition screening operation was compared with T 起飞 M 加速 and F Z1 Combinations; operating conditions are: V A V C or V D At that time, FZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP Minimum.

[0007] In the aforementioned principle and calculation method for the combination of working loads of the engine suspension structure, in S4, the process of combining the working conditions and calculation items of CCAR25.361(c) is as follows: For piston engines with 5 or more cylinders, the coefficient 1.25 in CCAR25.361(c)(1) is replaced with 1.33; for piston engines with 4, 3, and 2 cylinders, the coefficient 1.25 is replaced with 2, 3, and 4 respectively.

[0008] In the aforementioned principles and calculation methods for the load combination of the engine mount structure, in S4, the process of combining the load conditions and calculation items for CCAR25.363 is as follows: Only the lateral inertial force F borne by the engine mount needs to be considered. YN At this time, the maximum lateral load factor n Y= ±1.33, for a total of 2 operating conditions; if the maximum lateral load factor under the maneuvering condition is greater than 1.33, the larger value shall be taken. The maximum lateral load shall not be superimposed with any other load during use.

[0009] In the aforementioned principle and calculation method for the combination of working loads of the engine suspension structure, in S4, when combining the working conditions and calculation items of CCAR25.371, the situations specified in Articles 25.331, 25.341(a), 25.349, 25.351, 25.473, 25.479, and 25.481 need to be analyzed respectively.

[0010] In the aforementioned principles and calculation methods for the load combination of the engine mounting structure, the process of combining the load conditions and calculation items for item 25.331 is as follows: Four load conditions are selected from all cruise configuration maneuver balance, non-calibration maneuver, and calibration maneuver conditions: n zE Maximum, n zE Minimum, ω y Maximum, ω y Minimum; engine pull T under these four operating conditions 连续 F ZA F ZP M ZP Take the calculated value under the corresponding operating condition flight parameters; n zE For the normal overload at the engine's center of gravity, used to calculate F ZN ;ω y Used to calculate M gZ .

[0011] In the aforementioned principle and calculation method for the load combination of the engine mounting structure, the process of combining the load conditions and calculation items for the vertical discrete gust in clause 25.341(a) is as follows: Four load conditions are selected from all cruise configurations for the vertical discrete gust: n zE Maximum, n zE Minimum, ω y Maximum, ω y Minimum; T for these 4 operating conditions 连续 F ZA F ZP M ZP Take the calculated value of 1g under the same weight, altitude, and speed during level flight, n zE Used to calculate F ZN ω y Used to calculate M gZ ; The process of combining operating conditions and calculation terms for the lateral discrete gusts in clause 25.341(a) is as follows: Four operating conditions are selected from all cruise configuration lateral discrete gust cases: n yE Maximum absolute value, ω z The absolute value is the largest, and the reverse is considered separately; T for these four working conditions. 连续 F YA or F ZA F YP or F ZP M YP Or M ZP The corresponding calculated values ​​are taken for 1g at level flight, based on the weight, altitude, and speed. yE Used to calculate F YN ω z Used to calculate M gY ; The process of combining operating conditions and calculation terms for the asymmetric discrete inrush in clause 25.341(a) is as follows: Eight operating conditions are selected from all cruise configurations for asymmetric discrete inrush conditions: n zE Maximum, n zE Minimum, ω y Maximum, ω y minimum,n yE Maximum absolute value, ω z The absolute value is maximized, where n yE and ω z Considering the reverse side separately; T for these 8 working conditions 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated values ​​of weight, altitude, and speed corresponding to 1g in level flight, n zE Used to calculate F ZNn yE Used to calculate F YN ω y Used to calculate M gZ ω z Used to calculate M gY .

[0012] In the aforementioned principles and calculation methods for the load combination of engine mounting structures, the process of combining the load conditions and calculation items for item 25.349 is as follows: Six load conditions are selected from all cruise configuration roll maneuvers: n zE Maximum, n zE Minimum, ω y Maximum, ω y minimum,n yE The absolute value is maximized, where n yE Consider the reverse; T for these 6 operating conditions 连续 F ZA F ZP M ZP Take the calculated value of the flight parameters under the corresponding operating conditions, n zE Used to calculate F ZN n yE Used to calculate F YN ω y Used to calculate M gZ .

[0013] In the aforementioned principles and calculation methods for the load combination of the engine mounting structure, the process of combining the load conditions and calculation items for item 25.351 is as follows: Four load conditions are selected from all cruise configuration yaw maneuvers: n yE Maximum absolute value, ω z The absolute value is the largest, and the reverse sides are considered separately; T for these four working conditions. 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated value of the flight parameters under the corresponding operating conditions, n yE Used to calculate F YN ω z Used to calculate M gY .

[0014] In the aforementioned principles and calculation methods for the load combination of the engine suspension structure, the process of combining the load conditions and calculation items for the landing / water landing conditions specified in 25.473, 25.479, and 25.481 is as follows: Three load conditions are selected from all static symmetrical landing conditions: n xE Maximum, n zE Maximum, ω yMinimum; thrust, engine torque, and propeller 1P load are all assumed to be zero; n xE Used to calculate F XN n zE Used to calculate F ZN ω y Used to calculate M gZ ; The combination process of load conditions and calculation terms for dynamic symmetrical landing loads is as follows: The pitch angular velocity corresponding to the vertical overload extreme value is selected to calculate the engine mount load; n xE Used to calculate F XN n yE Used to calculate F YN n zE Used to calculate F ZN ω y Used to calculate M gZ Nacelle aerodynamics F ZA Refer to the extreme values ​​of dynamic water-receiving aerodynamic loads; The process of combining load cases and calculation terms for static water-coated conditions is as follows: Four load cases are selected from all static water-coated conditions: n xE Maximum, n zE Maximum, when tilted up ω y Maximum, when head down ω y Minimum; thrust, engine torque, and propeller 1P load are all assumed to be zero; pitch angular velocity ω y Consider the maximum and minimum values ​​separately; n xE Used to calculate F XN n zE Used to calculate F ZN ω y Used to calculate M gZ ; The combination process of load cases and calculation terms for dynamic symmetrical water-coating conditions is as follows: Seven load cases are selected from all dynamic symmetrical water-coating conditions: n xE Maximum, n xE minimum,n yE Maximum, n yE minimum,n zE Maximum, n zE Minimum, when head down ω y Minimum; thrust, engine torque, and propeller 1P load are all assumed to be zero; n xE Used to calculate F XN n yE Used to calculate F YN n zE Used to calculate F ZN ω y Used to calculate M gZ .

[0015] In the aforementioned principle and calculation method for the combination of working conditions and loads of the engine suspension structure, in S4, the process of combining the working conditions and calculation items of CCAR25.561 is as follows: including 6 working conditions: upward inertial overload, forward inertial overload, positive lateral inertial overload, negative lateral inertial overload, downward inertial overload, and backward inertial overload.

[0016] Advantages of this invention: Based on CCAR-25-R4 "Civil Aviation Regulations of China, Part 25", and combined with the current research status of engine propeller loads, this invention provides a systematic and relatively complete combination and summarization method for the load conditions of turboprop aircraft engine pylon structures. It provides a reference for the airworthiness compliance of turboprop aircraft engine pylon structures and a basis for the strength design analysis, usage restrictions and flight manual compilation of related structures.

[0017] This invention, based on airworthiness regulations and current research on propeller loads, uses the aircraft's flight maneuver envelope as a foundation. It calculates and analyzes engine performance parameters, aircraft overload, angular velocity, and other parameters under various operating conditions, ultimately combining these to form a relatively complete load calculation framework for the engine pylon structure. This invention achieves the following advantages: a) Based on the original airworthiness regulations and in light of the latest load research, the physical quantities that should be additionally considered in the operating condition calculations have been expanded, namely the 1P load. b) Regulations and reference instructions are given for the calculation process and direction of 1P load; c) By comprehensively reviewing all flight and landing (water landing) scenarios of the aircraft covered by the load clauses, the occurrence of omitted conditions has been greatly reduced; d) For all the working conditions that should be considered according to the clause, the invariants and variables were fully analyzed, and the simplification process of extreme value analysis greatly reduced the number of working conditions to be calculated without omitting the possibility of boundary conditions.

[0018] In summary, this invention, based on airworthiness regulations and incorporating the latest research findings on engine loads (1P load), comprehensively reviews all possible operating conditions of turboprop aircraft engine pylons, and provides the combination principles for various loads under each operating condition, thus pointing the way and providing direction for the calculation of engine pylon structural loads for similar aircraft. Attached Figure Description

[0019] Figure 1 This is a typical engine acceleration curve; Figure 2 This represents the typical flight maneuver envelope of an aircraft. Figure 3 The load method for propeller 1P load. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0022] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] The regulations upon which this invention is based: (1) CCAR25.361 engine torque; (2) CCAR25.363 Lateral loads on engine and auxiliary power unit brackets; (3) CCAR25.371 gyroscope load; (4) CCAR25.561 General Principles.

[0024] The physical meanings of the various symbols in this invention are shown in Table 1.

[0025] Table 1 Symbol Table

[0026] Example 1. A method for calculating the operating load of a turboprop aircraft engine mounting structure, see [link to example]. Figures 1-3Based on engine performance parameters and aircraft design characteristics, the operating conditions and load combinations of the engine pylon structure under various usage scenarios are obtained. Specifically, based on the airworthiness regulation CCAR-25-R4 "Civil Aviation Regulations of China, Part 25", and combined with the current research status of propeller loads, and taking the aircraft flight maneuver envelope as a basis, the engine performance parameters, aircraft overload, angular velocity, and other parameters under various operating conditions are calculated and analyzed, and finally combined to form a relatively complete load calculation condition for the engine pylon structure. The steps are as follows: (1) Based on the engine's basic performance parameters, the thrust, torque, engine speed, propeller speed, engine rotor and propeller blade moment of inertia, engine failure shutdown time, and maximum acceleration at the engine's rated and takeoff power are obtained, see [reference]. Figure 1 ; (2) Based on the typical maneuver envelope of the aircraft, the flight load coefficients at state points A, A1, and D1 are obtained, where V A The design maneuver speed under a 2.5g overload is V. A1 V D1 These represent the design maneuver speed and design dive speed under 1g level flight conditions, respectively. See Figure 2 ; (3) Calculate the engine 1P load based on parameters such as angle of attack and sideslip angle under aircraft maneuvering conditions. The calculation method is as follows: Figure 3 ; (4) Calculate and combine the loads under various working conditions based on 25.361, 25.363, 25.371 and 25.561.

[0027] Example 2. A method for calculating the operating load of a turboprop aircraft engine mounting structure, see [link to example]. Figures 1-3 ,include: (1) The required data obtained from the engine's basic performance parameters are as follows: Maximum shaft power P during takeoff 起飞 ; Maximum shaft power P under rated conditions 额定 ; Maximum engine thrust T at takeoff power 起飞 ; Maximum pulling force T of engine at rated power 额定 ; Engine rotor moment of inertia (about the axis of rotation) I1; The engine speed ω1 at which the maximum continuous power is achieved; The propeller speed ω2 at maximum continuous power; The moment of inertia of the propeller blades (about the axis of rotation) is I2.

[0028] (2) The typical flight load envelope of an aircraft (see...) Figure 2The flight load coefficients at points A, A1, and D1 are obtained and denoted as n. A n A1 n D1 , used to calculate the inertial load in this state; (3) Calculate the propeller load 1P based on the aircraft's flight parameters under various maneuvers. The calculation method for 1P load is as follows: Figure 3 Here, we assume the propeller rotates in the direction of flight but counterclockwise, then we utilize... Figure 3 The propeller aerodynamic force (F) was calculated using the method. YP or F ZP ), propeller 1P aerodynamic torque (M YP Or M ZP The direction is explained as follows: When the aircraft's angle of attack is positive, the left blade has a larger "combined angle of attack." Its aerodynamic force components—the "thrust" component perpendicular to the rotor disk plane (forward) and the "tangential drag" component parallel to the rotor disk plane (upward)—are both greater than those of the right blade, but in opposite directions. Therefore: 1) The direction of the propeller's 1P aerodynamic torque: downward along the Z-axis, with a positive value; 2) The direction of the propeller's 1P aerodynamic force: upward along the Z-axis, with a positive value.

[0029] Conversely, when the aircraft's angle of attack is negative: 1) The direction of the propeller's 1P aerodynamic torque: upward along the Z-axis, with a negative value; 2) The direction of the propeller's 1P aerodynamic force: downward along the Z-axis, with a negative value.

[0030] When the aircraft's sideslip angle is positive, the lower blade has a larger "combined sideslip angle." Its aerodynamic force components, the "thrust" component perpendicular to the rotor disk plane (forward) and the "tangential drag" component parallel to the rotor disk plane (to the left), are both greater than those of the upper blade, but in opposite directions. Therefore: 1) Direction of the propeller's 1P aerodynamic torque: along the positive Y-axis, with a positive value; 2) Direction of propeller 1P aerodynamic force: along the negative Y-axis, with positive values.

[0031] Conversely, when the aircraft's sideslip angle is negative: 1) Direction of propeller 1P aerodynamic torque: along the negative Y-axis, with a negative value; 2) The direction of the propeller's 1P aerodynamic force: along the positive Y-axis, with a negative value.

[0032] It is important to note that using Figure 3 The 1P load calculated by the formula is the 1P load for a pair of propeller blades (this load is defined in the whole machine coordinate system). In actual use, it needs to be converted according to the number of engine blades.

[0033] (4) Calculate the limiting torque generated by sudden engine stoppage. The calculation formula is as follows:

[0034] Where: deceleration time Δt A conservative value can be selected based on the Technical Advisory Manual for Airworthiness Standards of Transport Category Aircraft.

[0035] (5) Calculate the limiting torque generated by the engine's maximum acceleration. The calculation formula is as follows:

[0036] In the formula: This is the maximum angular acceleration of the engine rotor, which is obtained from the engine acceleration performance curve. Figure 1 This is a schematic diagram of the engine speed-time curve.

[0037] (6) Combine the operating conditions and calculation items for the engine torque in CCAR25.361(a)(1). Item (a)(1) is the engine pull T. 起飞 Torque 1.25M 起飞 Inertial force 0.75F ZN Nacelle aerodynamics 0.75F ZA 1P propeller force 0.75F ZP 1P propeller with a torque of 0.75M ZP Simultaneous loading conditions. Among them, T 起飞 M 起飞 and F ZN It is a constant. Therefore, for all values ​​at V... HA The 2.5g dynamic balance condition can be used to screen out 6 working conditions, and compared with T 起飞 1.25M 起飞 and 0.75F ZN Combined, i.e.: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP The minimum operating conditions corresponding to each.

[0038] (7) CCAR25.361 (a)(2) item is engine pull T 连续 Torque 1.25M 连续 Inertial force F ZN Nacelle aerodynamics F ZA 1P force F of the propeller ZP Propeller 1P torque M ZP Simultaneous loading conditions. Among them, T 连续 (Take the maximum value), M 连续and F ZN Since it is a constant, therefore for all V HA Six operating conditions were selected based on the 2.5g motor balance (the same as those in 25.361(a)(1)), and were compared with T. 连续 1.25M 连续 and F ZN Combination, i.e.: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP The minimum corresponding working conditions; (8) CCAR25.361 (a)(3) item is engine pull T 起飞 Torque 1.25×1.6M 起飞 Inertial force F Z1 Nacelle aerodynamics F ZA Simultaneous loading conditions. Among them, T 起飞 (Take the maximum value), M 起飞 and F Z1 It is a constant. Because in all V... A and V C 1g level flight condition F ZP With M ZP Simultaneously reaching positive (negative) extreme values, therefore, for each V... A and V C Six operating conditions were selected based on the 1g level flight condition, and compared with T 起飞 1.25M 起飞 and 0.75F ZN Combination, i.e.: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP The minimum corresponding working conditions, totaling 12 working conditions; (9) CCAR25.361 (b)(1) item is torque M 停车 Inertial force F Z1 Nacelle aerodynamics F ZA Simultaneous loading conditions. Among them, M 停车 and F Z1 Since it is a constant, therefore for all V A and V C Four operating conditions were selected from the 1g level flight conditions, and compared with M shutdown and F Z1 Combination, i.e., V A or V C At that time, F ZA Maximum, F ZAThe minimum corresponding working conditions; (10) CCAR25.361 (b)(2) is the tensile force T 起飞 Torque M 加速 Inertial force F Z1 Nacelle aerodynamics F ZA 1P force F of the propeller ZP Propeller 1P torque M ZP Simultaneous loading conditions. Among them, T 起飞 M 加速 and F Z1 Since it is a constant, it should be applied to all V. A V C V D Six operating conditions were selected based on the 1g level flight condition, and compared with T 起飞 M 加速 and F Z1 Combination, i.e.: V A V C or V D F at that time ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP The minimum corresponding working conditions are 18 in total.

[0039] (11) In CCAR25.361 (c), only (c)(1), i.e., coefficient 1.25, needs to be considered for turboprop aircraft, and this coefficient has already been taken into account in the engine torque of (a)(1), (a)(2), and (a)(3); for other piston engines with 5 or more cylinders, the above 1.25 is replaced with 1.33; for piston engines with 4, 3, and 2 cylinders, 1.25 is replaced with 2, 3, and 4 respectively.

[0040] (12) The maximum lateral load factor under aircraft maneuvering conditions in CCAR 25.363 can be calculated from the total load of the aircraft's yaw maneuver. One-third of the load factor for condition A is approximately 2.5 / 3 = 0.833. Both are usually less than the 1.33 specified in 25.363(a)(1). Therefore, clause 25.363 usually only needs to consider the lateral inertial force F borne by the engine mount. YN The load is calculated in both directions, resulting in two operating conditions. If the maximum lateral load factor under the maneuvering condition is greater than 1.33, the larger value is taken. This load is not superimposed on any other load during use.

[0041] (13) CCAR 25.371 stipulates that the support structure of any engine or auxiliary power unit must be designed to withstand loads, including gyroscopic loads, generated under the conditions specified in Clauses 25.331, 25.341(a), 25.349, 25.351, 25.473, 25.479, and 25.481, and the engine or auxiliary power unit must be at the maximum speed corresponding to that condition. To comply with this clause, the pitch maneuver requirements of Clause 25.331(c)(1) must be met until a positive limiting maneuver load factor (point A2 of Clause 25.333(b)) is reached. Therefore, it is necessary to analyze the conditions specified in Clauses 25.331, 25.341(a), 25.349, 25.351, 25.473, 25.479, and 25.481 respectively. (14) 25.331 is the engine pull T 连续 Torque M 连续 Inertial force F ZN Nacelle aerodynamics F ZA 1P force F of the propeller ZP Propeller 1P torque M ZP gyro torque M gZ Simultaneous loading conditions. Among them, M 连续 For a constant value (M) 额定 Therefore, four operating conditions were selected from all cruise configuration maneuver balance, non-calibration maneuver, and calibration maneuver situations: F ZN Maximum, F ZN Minimum, M gZ Maximum, M gZ Minimum. Engine pull T under these four operating conditions. 连续 F ZA F ZP M ZP Take the calculated values ​​under the corresponding operating conditions and flight parameters.

[0042] In (15)25.341(a), the vertical discrete gust is the tension T. 连续 Torque M 连续 Inertial force F ZN Nacelle aerodynamics F ZA 1P force F of the propeller ZP Propeller 1P torque M ZP gyro torque M gZ Simultaneous loading conditions. Where M... 连续 For a constant value (M) 额定 Therefore, four operating conditions were selected for all cruise configurations under vertical discrete gust conditions: F ZN Maximum, F ZN Minimum, M gZ Maximum, MgZ Minimum. T for these four operating conditions. 连续 F ZA F ZP M ZP Take the calculated value of 1g under the same weight, altitude and speed in level flight.

[0043] The lateral discrete gust in (16)25.341(a) is the tension T. 连续 Torque M 连续 Inertial force F YN Inertial force F ZN (1g), nacelle aerodynamics F YA or F ZA 1P force F of the propeller YP or F ZP Propeller 1P torque M YP Or M ZP gyro torque M gY Simultaneous loading conditions. Where M... 连续 For a constant value (M) 额定 ), F ZN To ensure a constant value, four operating conditions were selected for all cruise configurations under lateral discrete gust conditions: F YN Maximum absolute value, M gY The absolute value is the largest, and the reverse is considered separately. The T values ​​for these four operating conditions are... 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated values ​​for the corresponding weight, altitude, and speed at 1g during level flight.

[0044] The asymmetric discrete gust load in (17)25.341(a) is the tensile force T. 连续 Torque M 连续 Inertial force F YN or F ZN Nacelle aerodynamics F YA or F ZA 1P force F of the propeller YP or F ZP Propeller 1P torque M YP Or M ZP gyro torque M gY Or M gZ Simultaneous loading conditions. Where M... 连续 For a constant value (M) 额定 Therefore, eight operating conditions were selected from all cruise configurations for asymmetric discrete inrush conditions: namely F ZN Maximum, F ZN Minimum, M gZ Maximum, MgZ Minimum, F YN Maximum absolute value, M gY The absolute value is the largest, where F YN and M gY Consider the reverse directions separately. The T values ​​for these 8 operating conditions. 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated values ​​for the corresponding weight, altitude, and speed at 1g during level flight.

[0045] (18) 25.349 is the tensile force T 连续 Torque M 连续 Inertial force F YN or F ZN Nacelle aerodynamics F ZA 1P force F of the propeller ZP Propeller 1P torque M ZP gyro torque M gZ Simultaneous loading conditions. Where M... 连续 For a constant value (M) 额定 Therefore, six operating conditions were selected from all cruise configuration roll maneuvers: F ZN Maximum, F ZN Minimum, M gZ Maximum, M gZ Minimum, F YN The absolute value is the largest, where F YN Consider the reverse. The T values ​​for these 6 operating conditions. 连续 F ZA F ZP M ZP Take the calculated values ​​under the corresponding operating conditions and flight parameters.

[0046] (19) 25.351 is the engine pull T 连续 Torque M 连续 Inertial force F YN or F Z1 (1g), nacelle aerodynamics F YA or F ZA 1P force F of the propeller YP or F ZP Propeller 1P torque M YP Or M ZP gyro torque M gY Simultaneous loading conditions. Where M... 连续 For a constant value (M) 额定 Therefore, four operating conditions were selected for all cruise configuration yaw maneuvers: F YN Maximum absolute value, MgY The absolute value is the largest, so we consider the reverse sides separately. The T values ​​for these four operating conditions are... 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated values ​​under the corresponding operating conditions and flight parameters.

[0047] (20) Landing (water landing) conditions as specified in 25.473, 25.479 and 25.481.

[0048] The static symmetrical landing load case is the inertial force F ZN Inertial force F XN Nacelle aerodynamics F ZA gyro torque M gZ Simultaneous loading conditions. Three loading conditions were selected from all static symmetrical landing scenarios: F XN Maximum, F ZN Maximum, M gZ Minimum (aircraft nose down). Since landing typically uses idle power, thrust, engine torque, and propeller 1P load can all be assumed to be zero.

[0049] The dynamic symmetrical landing load case is the inertial force F ZN Inertial force F XN Inertial force F YN Nacelle aerodynamics F ZA gyro torque M gZ Simultaneous load conditions. Typically, due to the extremely small directional and lateral overloads under dynamic symmetrical landing loads, the flight parameters corresponding to the extreme vertical overload can be selected to calculate the engine mount load. In this case, two operating conditions are selected: F... ZN Maximum, F ZN Minimum; nacelle aerodynamic force F ZA Refer to the extreme values ​​of dynamic water-receiving aerodynamic loads.

[0050] The static water-load condition (if any) is the inertial force F. ZN Inertial force F XN Nacelle aerodynamics F ZA gyro torque M gZ Simultaneous loading conditions. Therefore, four operating conditions were selected from all static water-coated conditions: namely, F... XN Maximum, F ZN Maximum, M gZ Maximum (head up), M gZ Minimum (aircraft nose down). Since water landing typically uses idle power, thrust, engine torque, and propeller 1P load can all be assumed to be zero.

[0051] The dynamic symmetrical water load condition (if present) is the inertial force F. ZN Inertial force F XN、 Inertial force F YN Nacelle aerodynamics F ZA gyro torque M gZ Simultaneous loading conditions. Seven operating conditions were selected from all dynamic symmetrical water-coated scenarios: F XN Maximum, F XN Minimum, F YN Maximum, F YN Minimum, F ZN Maximum, F ZN Minimum, M gZ Minimum (aircraft nose down). Since water landing typically uses idle power, thrust, engine torque, and propeller 1P load can all be assumed to be zero.

[0052] (21) Clause 25.561 describes the inertial load conditions for emergency landing of an aircraft, requiring that the engine be reliably fixed under the various limit inertial load coefficients specified in the regulations. The coefficients are as follows: (i) Upward, 3.0; (ii) Forward, 9.0; (iii) Lateral, 3.0 for the fuselage; (iv) Downward, 6.0; (v) Rearward, 1.5. When considering the load conditions, the lateral direction should also be considered in the opposite direction. Therefore, according to this clause, there are a total of 6 load conditions: upward inertial overload condition, forward inertial overload condition, positive lateral inertial overload condition, negative lateral inertial overload condition, downward inertial overload condition, and rearward inertial overload condition.

[0053] This invention, based on CCAR-25-R4 (Part 25 of the Civil Aviation Regulations of China) and considering the current research status of engine propeller loads, expands the calculation items for engine pylon structures of turboprop aircraft and provides detailed calculation methods and directional guidelines. Furthermore, it offers a systematic and relatively complete method for combining and summarizing operating conditions, and provides calculation methods for key items. This provides guidance and direction for load calculation of engine pylon structures in similar aircraft, offers a reference for the airworthiness compliance of load clauses for engine pylon structures, and provides a basis for strength design analysis, usage restrictions, and flight manual compilation of related structures.

[0054] The above-described embodiments merely illustrate the implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A method for calculating the operating load of a turboprop aircraft engine suspension structure, characterized in that, include: S1. Based on the engine's basic performance parameters, obtain the thrust, torque, engine speed, propeller speed, engine rotor and propeller blade moment of inertia, engine failure downtime, and maximum acceleration at the engine's rated and takeoff power. S2. Based on the typical maneuver envelope of the aircraft, the flight load coefficients at state points A, A1, and D1 are obtained, corresponding to the design maneuver speed V under a 2.5g overload. A Design speed V in 1g level flight condition A1 Design dive speed V D1 ; S3. Calculate the engine 1P load based on the angle of attack and sideslip angle parameters of the aircraft under maneuvering conditions; S4. Calculate and combine loads under various working conditions based on CCAR25.361, CCAR25.363, CCAR25.371 and CCAR25.

561.

2. The method for calculating the working load of the turboprop aircraft engine mounting structure according to claim 1, characterized in that: In S4, the process of combining the working conditions and calculation items for CCAR25.361(a)(1) is as follows: From all V HA Six operating conditions were selected from the 2.5g motor balance situation and compared with T 起飞 1.25M 起飞 and 0.75F ZN Combination; the 6 operating conditions are: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP Minimum; The process of combining operating conditions and calculation items for CCAR25.361(a)(2) is as follows: From all V HA Six working conditions identical to those in 25.361(a)(1) were selected from the 2.5g dynamic balance conditions and compared with T. 连续 1.25M 连续 and F ZN combination; The process of combining the operating conditions and calculation items for CCAR25.361(a)(3) is as follows: V A and V C Six operating conditions were selected based on the 1g level flight condition, and compared with T 起飞 1.25M 起飞 and 0.75F ZN Combination; V A or V C The six operating conditions are: F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP The minimum, with a total of 12 operating conditions.

3. The working load combination principle and calculation method of the engine suspension structure according to claim 1, characterized in that, In S4, the process of combining the working conditions and calculation items for CCAR25.361(b)(1) is as follows: For all V A and V C Four operating conditions were selected from the 1g level flight conditions and compared with M. 停车 and F Z1 Combination; the four operating conditions are: V A or V C At that time, F ZA Maximum, F ZA Minimum; The process of combining operating conditions and calculation items for CCAR25.361(b)(2) is as follows: For all V A ~V D The 1g level flight condition screening working condition, and compared with T 起飞 M 加速 and F Z1 Combinations; operating conditions are: V A V C or V D At that time, F ZA Maximum, F ZA Minimum, F ZP Maximum, F ZP Minimum, M ZP Maximum, M ZP Minimum.

4. The working load combination principle and calculation method of the engine suspension structure according to claim 1, characterized in that, In S4, the process of combining the operating conditions and calculation items of CCAR25.361(c) is as follows: For piston engines with 5 or more cylinders, the coefficient 1.25 in CCAR25.361(c)(1) is replaced with 1.33; for piston engines with 4, 3, and 2 cylinders, the coefficient 1.25 is replaced with 2, 3, and 4 respectively.

5. The working load combination principle and calculation method of the engine suspension structure according to claim 1, characterized in that, In S4, the process of combining the operating conditions and calculation terms for CCAR25.363 is as follows: Only the lateral inertial force F borne by the engine mount needs to be considered. YN At this time, the maximum lateral load factor n Y= ±1.33, for a total of 2 operating conditions; if the maximum lateral load factor under the maneuvering condition is greater than 1.33, the larger value shall be taken. The maximum lateral load shall not be superimposed with any other load during use.

6. The working load combination principle and calculation method of the engine suspension structure according to claim 1, characterized in that, In S4, when combining operating conditions and calculation items for CCAR25.371, the situations specified in Clauses 25.331, 25.341(a), 25.349, 25.351, 25.473, 25.479, and 25.481 must be analyzed respectively.

7. The working load combination principle and calculation method of the engine suspension structure according to claim 6, characterized in that, The process of combining operating conditions and calculation items for item 25.331 is as follows: Four operating conditions are selected from all cruise configuration maneuver balance, non-verification maneuver, and verification maneuver cases: n zE Maximum, n zE Minimum, ω y Maximum, ω y Minimum; engine pull T under these four operating conditions 连续 F ZA F ZP M ZP Take the calculated value under the corresponding operating condition flight parameters; n zE For the normal overload at the engine's center of gravity, used to calculate F ZN ;ω y Used to calculate M gZ .

8. The working load combination principle and calculation method of the engine suspension structure according to claim 6, characterized in that, The process of combining the operating conditions and calculation terms for the vertical discrete gusts in clause 25.341(a) is as follows: Four operating conditions are selected from all cruise configurations for vertical discrete gusts: n zE Maximum, n zE Minimum, ω y Maximum, ω y Minimum; T for these 4 operating conditions 连续 F ZA F ZP M ZP Take the calculated value of 1g under the same weight, altitude, and speed during level flight, n zE Used to calculate F ZN ω y Used to calculate M gZ ; The process of combining operating conditions and calculation terms for the lateral discrete gusts in clause 25.341(a) is as follows: Four operating conditions are selected from all cruise configuration lateral discrete gust cases: n yE Maximum absolute value, ω z The absolute value is the largest, and the reverse is considered separately; T for these four working conditions. 连续 F YA or F ZA F YP or F ZP M YP Or M ZP The corresponding calculated values ​​are taken for 1g at level flight, based on the weight, altitude, and speed. yE Used to calculate F YN ω z Used to calculate M gY ; The process of combining operating conditions and calculation terms for the asymmetric discrete inrush in clause 25.341(a) is as follows: Eight operating conditions are selected from all cruise configurations for asymmetric discrete inrush: n zE Maximum, n zE Minimum, ω y Maximum, ω y minimum,n yE Maximum absolute value, ω z The absolute value is maximized, where n yE and ω z Considering the reverse side separately; T for these 8 working conditions 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated values ​​of weight, altitude, and speed corresponding to 1g in level flight, n zE Used to calculate F ZN n yE Used to calculate F YN ω y Used to calculate M gZ ω z Used to calculate M gY .

9. The working load combination principle and calculation method of the engine suspension structure according to claim 6, characterized in that, The process of combining the operating conditions and calculation items for item 25.349 is as follows: Six operating conditions are selected from all cruise configuration roll maneuvers: n zE Maximum, n zE Minimum, ω y Maximum, ω y minimum,n yE The absolute value is maximized, where n yE Consider the reverse; T for these 6 operating conditions 连续 F ZA F ZP M ZP Take the calculated value of the flight parameters under the corresponding operating conditions, n zE Used to calculate F ZN n yE Used to calculate F YN ω y Used to calculate M gZ .

10. The working load combination principle and calculation method of the engine suspension structure according to claim 6, characterized in that, The process of combining operating conditions and calculation items for item 25.351 is as follows: Four operating conditions are selected from all cruise configuration yaw maneuvers: n yE Maximum absolute value, ω z The absolute value is the largest, and the reverse sides are considered separately; T for these four working conditions. 连续 F YA or F ZA F YP or F ZP M YP Or M ZP Take the calculated value of the flight parameters under the corresponding operating conditions, n yE Used to calculate F YN ω z Used to calculate M gY .

Images