A method and system for quantitative evaluation and optimization of oil return performance of an aviation speed reducer

Abstract

The present application relates to a kind of aviation retarder oil return performance quantitative evaluation and optimization method and system, the method obtains the oil return port flow time domain data under multiple preset operating conditions, inlet total flow and internal oil phase volume fraction field, and adopts sliding window double criterion to identify stable oil return stage;Calculate stable average oil return rate, space oil accumulation rate, oil return fluctuation coefficient and oil return response time and other indexes, and then calculate the comprehensive oil return performance index of each operating condition and the comprehensive oil return performance index of multiple operating conditions.Based on the above evaluation index, determine the structure optimization direction, and adjust the oil return structure parameter.The method realizes the multidimensional quantitative evaluation and multiple operating condition comprehensive diagnosis of the oil return performance of aviation retarder, can identify the main oil return performance abnormal type and clear corresponding structure optimization direction, to provide reliable basis for the adjustment of oil return structure parameter, improve the pertinence of oil return performance evaluation and structure optimization.

Description

Technical Field

[0001] This invention relates to the field of lubrication and cooling technology for aircraft transmission systems, specifically to a method and system for quantitative evaluation and optimization of oil return performance of aircraft gearboxes. Background Technology

[0002] Aircraft gearboxes are a crucial component of aircraft transmission systems, typically housing gears, bearings, and corresponding lubrication and return structures. During operation at high speeds, under heavy loads, and with changing attitudes, the lubricating oil undergoes complex flow patterns within the gearbox due to the combined effects of gear meshing, centrifugal oil ejection, gravity backflow, wall adhesion, and localized flow guidance structures. This flow includes splashing, accumulation, stagnation, and backflow. While lubricating moving parts like gears and bearings, the lubricating oil also plays a role in cooling and heat transfer. Therefore, ensuring the timely and stable discharge of lubricating oil from the return port is a critical factor to consider during the design of the gearbox's lubrication system.

[0003] Currently, for the flow process of lubricating oil inside gearboxes or aircraft reducers, numerical calculation methods such as the finite volume method, smoothed particle hydrodynamics, and lattice Boltzmann method are commonly used to establish a gas-liquid two-phase flow model to analyze the motion process of the lubricating oil inside the reducer. After completing the numerical calculation, the lubrication state and return oil state inside the reducer are generally judged by lubricating oil distribution cloud maps, return oil flow curves, or corresponding experimental observation results.

[0004] In existing oil return performance analysis processes, it is usually necessary to determine whether the reducer has entered a stable oil return state based on the curve of the return oil flow rate over time. However, the determination of the stable phase often relies on the analyst's manual observation and selection of the flow rate curve. Different analysts or different operating conditions may select different stable time intervals, resulting in a lack of unified judgment criteria for the evaluation results obtained based on the stable time interval.

[0005] Meanwhile, existing methods for evaluating oil return performance often use single parameters such as return port flow rate or return rate to characterize the overall oil return situation of the reducer. However, the lubricating oil inside the reducer may experience local accumulation or stagnation during the return flow process. Therefore, relying solely on flow rate data at the return port is insufficient to characterize the oil distribution in different areas of the reducer and the degree of internal oil accumulation. Furthermore, existing lubricating oil distribution cloud maps are typically used primarily for visualizing the internal flow state. There is a lack of unified data processing and evaluation methods between the time-domain data of the return port flow rate and the spatial distribution data of the internal lubricating oil. Consequently, it is difficult to quantitatively compare the oil return status between different structural designs or operating conditions.

[0006] Furthermore, the oil return performance of aircraft gearboxes is not only related to the amount of oil returned, but also to flow fluctuations during the stable oil return phase, oil retention inside the gearbox, and the oil return establishment process after startup or operating condition switching. Existing evaluation methods based primarily on oil return rate cannot simultaneously characterize the adequacy of oil return, the degree of internal oil accumulation, the stability of oil return flow, and the dynamic response process of oil return, thus making it difficult to form a unified evaluation result that can comprehensively characterize the oil return status under different operating conditions.

[0007] Furthermore, after obtaining the evaluation results of the reducer's oil return performance, there is usually a lack of clear correspondence between the existing evaluation results and the reducer's structural parameters. For example, when the reducer experiences insufficient oil return, internal oil accumulation, fluctuations in oil return flow, or sluggish oil return response under a certain operating condition, the existing evaluation methods cannot directly determine what adjustments should be made to the structure such as the size of the oil return port, the oil return channel, the location of the oil return port, the flow guiding structure, or the cavity wall based on the evaluation results. This results in a certain degree of disconnect between the oil return performance evaluation and subsequent structural optimization.

[0008] Therefore, it is necessary to improve the analysis and evaluation methods of the oil return performance of aircraft gearboxes, so as to establish a quantitative evaluation method that can uniformly process the stable oil return stage, internal oil distribution, oil return flow rate changes and oil return state under different operating conditions, and make the evaluation results correspond to the oil return structure design of aircraft gearboxes. Summary of the Invention

[0009] This invention provides a method and system for quantitative evaluation and optimization of the oil return performance of aircraft gearboxes. The purpose is to solve the problems of existing evaluation methods for the oil return performance of aircraft gearboxes, which rely on manual judgment, have single evaluation indicators, are difficult to take into account both internal oil accumulation and dynamic response, and lack a clear correspondence between evaluation results and structural optimization.

[0010] To achieve the above objectives, the first aspect of the present invention provides a method for quantitative evaluation and optimization of the oil return performance of an aircraft gearbox, comprising the following steps: Acquire time-domain data of return oil flow, total inlet flow, and internal oil phase volume fraction field of the aircraft gearbox under multiple preset operating conditions; Based on the time-domain data of the return oil port flow rate, a sliding window dual criterion is used to identify the stable return oil stage corresponding to each preset working condition. Based on the stable oil return stage, the total inlet flow rate, and the internal oil phase volume fraction field, calculate the oil return performance evaluation index corresponding to each preset working condition. The oil return performance evaluation index includes the stable average oil return rate, the space oil accumulation rate, the oil return fluctuation coefficient, and the oil return response time. Based on the oil return performance evaluation index corresponding to each preset working condition, calculate the comprehensive oil return performance index corresponding to each preset working condition. Based on the comprehensive oil return performance index corresponding to each preset working condition and the corresponding working condition weight, the multi-working-condition comprehensive oil return performance index of the aircraft gearbox is calculated. Based on the oil return performance evaluation indicators, the comprehensive oil return performance index, and the multi-condition comprehensive oil return performance index, the structural optimization direction of the aircraft gearbox is determined. Adjust the oil return structure parameters of the aircraft gearbox according to the aforementioned structural optimization direction.

[0011] Furthermore, methods for obtaining time-domain data of return oil flow, total inlet flow, and internal oil phase volume fraction field of an aircraft gearbox under multiple preset operating conditions include: Establish a three-dimensional model of the aircraft decelerator; Extract the internal fluid domain of the aircraft deceleration unit from the three-dimensional model; A numerical simulation model of gas-liquid two-phase flow is established based on the internal fluid domain. The gas-liquid two-phase flow numerical simulation model was used to simulate the gas-liquid two-phase flow under multiple preset working conditions, and the simulation results corresponding to each preset working condition were obtained. The time-domain data of the return oil port flow rate, the total inlet flow rate, and the internal oil phase volume fraction field are obtained from the simulation results corresponding to each preset working condition.

[0012] Furthermore, the method for identifying the stable oil return stage corresponding to each preset operating condition using a sliding window dual-criteria method includes: The time-domain data of the return oil port flow rate is divided into multiple consecutive time windows according to a preset time window length. Extract the return oil port flow data within each time window as the window return oil port flow data for the corresponding time window, and perform average processing on the window return oil port flow data to obtain the window average return oil port flow corresponding to each time window. Based on the return oil flow rate data and the average return oil flow rate of each time window, calculate the fluctuation degree of the return oil flow rate of each time window. Based on the degree of change between the average return oil flow rate of two adjacent time windows and the degree of fluctuation of the return oil flow rate of each time window, multiple time windows are screened using dual criteria. When the dual criteria are met in multiple consecutive time windows, and the return oil flow rate value in the time domain data of the return oil flow rate no longer continuously increases or decreases over time after the start time of the time window when the dual criteria are first met, the stable return oil stage is determined.

[0013] Furthermore, the method for calculating the stable average oil return rate includes: Extract the return oil port flow rate data during the stable return oil phase from the time domain data of the return oil port flow rate to obtain the stable phase return oil port flow rate data. The average flow rate of the return oil port during the stable phase is obtained by averaging the return oil port flow rate during the stable phase. The stable average return rate is calculated based on the average return flow rate at the return port during the stable phase and the total inlet flow rate.

[0014] Furthermore, the method for calculating the space oil accumulation rate includes: The internal oil volume at each storage time during the stable oil return stage is calculated based on the internal oil phase volume fraction field. The average internal oil volume at each storage time during the stable oil return phase is averaged to obtain the average internal oil accumulation volume during the stable phase. The spatial oil accumulation rate is calculated based on the average internal oil accumulation volume during the stable phase and the effective volume of the internal fluid domain.

[0015] Furthermore, the method for calculating the return oil fluctuation coefficient includes: Based on the return oil flow rate data of the stable phase and the average return oil flow rate of the stable phase, the dispersion of the return oil flow rate within the stable return oil phase is calculated. The return oil fluctuation coefficient is calculated based on the dispersion of the return oil flow rate and the average return oil flow rate during the stable phase.

[0016] Furthermore, the calculation of the oil return response time includes: The return oil response judgment criterion is determined based on the average flow rate at the return oil port during the stable phase. Compare each return oil port flow rate value in the time domain data of the return oil port flow rate with the return oil response judgment benchmark to determine the moment when the return oil port flow rate value in the time domain data of the return oil port flow rate first reaches the return oil response judgment benchmark. The time is defined as the oil return response time.

[0017] Furthermore, the method for calculating the comprehensive oil return performance index and the multi-condition comprehensive oil return performance index includes: The stable average oil return rate, spatial oil accumulation rate, oil return fluctuation coefficient and oil return response time corresponding to each preset working condition are respectively processed into dimensionless evaluation indexes corresponding to each preset working condition. The comprehensive oil return performance index corresponding to each preset working condition is obtained by weighted calculation based on the dimensionless evaluation index corresponding to each preset working condition. The weight of each preset operating condition is determined based on its importance, the proportion of flight mission duration, the proportion of speed range, or the test evaluation requirements. The multi-condition comprehensive oil return performance index is obtained by weighting the comprehensive oil return performance index corresponding to each preset working condition and the corresponding working condition weight.

[0018] Furthermore, the method for determining the structural optimization direction of the aircraft gearbox and adjusting the oil return structure parameters of the aircraft gearbox includes: Based on the comprehensive oil return performance index corresponding to each preset working condition and the comprehensive oil return performance index of the multi-working condition, the working condition to be optimized is determined. The stable average oil return rate, space oil accumulation rate, oil return fluctuation coefficient, and oil return response time corresponding to the working condition to be optimized are compared with the corresponding target oil return rate, the upper limit of the space oil accumulation rate, the upper limit of the oil return fluctuation coefficient, and the upper limit of the oil return response time, respectively, to obtain the index comparison results. The optimization conditions corresponding to the working condition to be optimized are determined based on the comparison results of the aforementioned indicators, wherein: The first optimization condition is: the stable average oil return rate is lower than the corresponding target oil return rate, and the space oil accumulation rate is higher than the corresponding upper limit of the space oil accumulation rate. The second optimization condition is: the stable average oil return rate is not lower than the corresponding target oil return rate, and the space oil accumulation rate is higher than the corresponding upper limit of the space oil accumulation rate. The third optimization condition is: the return oil fluctuation coefficient is higher than the corresponding allowable upper limit of the return oil fluctuation coefficient; The fourth optimization condition is: the oil return response time is higher than the corresponding upper limit of the allowable oil return response time; When the first optimization condition is met, at least one first oil return structure parameter to be adjusted is determined from the oil return port cross section, oil return channel cross section, local structure of oil return channel, and oil return port position. When the second optimization condition is met, at least one second oil return structure parameter to be adjusted is determined from the bottom guide structure of the cavity, the oil guide groove, the oil guide rib and the inclination angle of the cavity wall. When the third optimization condition is met, at least one third oil return structure parameter to be adjusted is determined from the oil return port cross section, the transition of the oil guide channel cross section, the cavity structure near the oil return port, and the nozzle flow distribution. When the fourth optimization condition is met, at least one fourth return oil structure parameter to be adjusted is determined from the following: the guide path from the oil collection area to the return oil port, the return oil port height, the return oil port position, and the guide structure. The oil return structure of the aircraft gearbox is adjusted according to at least one of the first, second, third, and fourth oil return structure parameters to be adjusted.

[0019] To achieve the above objectives, a second aspect of the present invention provides a quantitative evaluation and optimization system for the oil return performance of an aircraft gearbox, comprising: The data acquisition module is used to acquire time-domain data of return oil flow, total inlet flow, and internal oil phase volume fraction field of the aircraft gearbox under multiple preset operating conditions. The stable oil return stage identification module is used to identify the stable oil return stage corresponding to each preset working condition based on the time domain data of the oil return port flow rate using a sliding window dual criterion. The oil return performance evaluation index calculation module is used to calculate the oil return performance evaluation index corresponding to each preset working condition based on the stable oil return stage, the total inlet flow rate, and the internal oil phase volume fraction field. The oil return performance evaluation index includes the stable average oil return rate, the spatial oil accumulation rate, the oil return fluctuation coefficient, and the oil return response time. The comprehensive oil return performance index calculation module is used to calculate the comprehensive oil return performance index corresponding to each preset working condition based on the oil return performance evaluation index corresponding to each preset working condition. The multi-condition comprehensive oil return performance index calculation module is used to calculate the multi-condition comprehensive oil return performance index of the aircraft gearbox based on the comprehensive oil return performance index corresponding to each preset condition and the corresponding condition weight. The structural optimization direction determination module is used to determine the structural optimization direction of the aircraft gearbox based on the oil return performance evaluation index, the comprehensive oil return performance index and the multi-condition comprehensive oil return performance index corresponding to each preset working condition. The oil return structure parameter adjustment module is used to determine the oil return structure parameters to be adjusted according to the structure optimization direction.

[0020] The beneficial effects of this invention are: Compared with existing technologies, this invention provides a quantitative evaluation and optimization method and system for the oil return performance of aircraft gearboxes. It jointly analyzes the time-domain data of the oil return port flow rate and the internal oil phase volume fraction field of the aircraft gearbox. A sliding window dual-criteria approach is used to identify the stable oil return stage. Based on the stable average oil return rate, spatial oil accumulation rate, oil return fluctuation coefficient, and oil return response time, the oil return performance under different operating conditions is quantitatively characterized. Furthermore, a unified evaluation of multiple indicators and operating conditions is achieved through a comprehensive oil return performance index and a multi-condition comprehensive oil return performance index. Simultaneously, the weak links in the oil return process and the direction of structural optimization are determined based on the relationship between each evaluation indicator and its corresponding evaluation benchmark. This reduces the subjectivity caused by manually selecting the stable stage, enabling a comprehensive evaluation of oil return sufficiency, internal oil accumulation degree, oil return stability, and dynamic response. Finally, a correspondence is established between the evaluation results and the optimization of the oil return port, oil return channel, flow guiding structure, and cavity structure. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0022] Figure 1 This is a flowchart of a method for quantitative evaluation and optimization of oil return performance of an aircraft gearbox, as disclosed in an embodiment of the present invention.

[0023] Figure 2 This is a schematic diagram of a data acquisition and gas-liquid two-phase flow simulation process disclosed in an embodiment of the present invention.

[0024] Figure 3 This is a schematic diagram of a method for identifying the stable oil return stage using a sliding window dual-criteria method, as disclosed in an embodiment of the present invention.

[0025] Figure 4 This is a structural block diagram of a quantitative evaluation and optimization system for the oil return performance of an aircraft gearbox, as disclosed in an embodiment of the present invention. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0027] According to embodiments of the present invention, it should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the following methods, in some cases the steps shown or described may be executed in a different order than that shown here.

[0028] like Figure 1 As shown, this invention provides a method for quantitative evaluation and optimization of the oil return performance of aircraft gearboxes, the method comprising: Step S100: Obtain the time-domain data of the return oil port flow rate, the total inlet flow rate, and the internal oil phase volume fraction field of the aircraft reducer under multiple preset operating conditions.

[0029] Specifically, in this embodiment, such as Figure 2First, a 3D model of the aircraft gearbox is established, and the internal fluid domain is extracted based on the oil inlet, oil return port, and the main flow path of the oil within the gearbox. During modeling, the oil inlet, oil return port, gears, casing walls, and the main channels or wall structures through which the oil flows are retained. Structures such as bearings, seals, fasteners, and small chamfers and roundings, which are not directly related to the evaluation of oil return performance and would significantly increase computational load, can be simplified without altering the main flow channels. Through this process, unnecessary computational units can be reduced while retaining the main geometric boundaries affecting the oil return characteristics.

[0030] In one specific implementation, the fluid domain inside the aircraft gearbox cavity can be extracted in SolidWorks. Non-critical geometric features such as rounded corners and chamfers in the fluid domain model are deleted. The internal fluid domain is then assembled with the gears according to the actual assembly relationship and exported in STP format. This method is only an example of 3D model construction, and the present invention does not limit the specific 3D modeling software and intermediate data format.

[0031] After obtaining the internal fluid domain, a numerical simulation model of the gas-liquid two-phase flow of the aircraft gearbox is established. In one specific implementation, XFlow is used to establish an internal multiphase flow simulation project, and the three-dimensional model of the aircraft gearbox is imported; the rotation centers of the driving wheel and driven wheel and the gear angular velocities are set; the lubricating oil inlet is set as a velocity inlet and is set as a liquid phase, and the oil return port is set as a pressure outlet and the outlet pressure is set.

[0032] For the flow physics model, a multiphase flow model can be selected, and a multiphase solution method and turbulence model suitable for two-phase flow calculations can be set. For example, the flow model can be set to Multiphase, the multiphase model to Particle-based tracking, and the turbulence model to Wall-Adapting Local-Eddy (WALE). Simultaneously, external accelerations are set along the coordinate axes to represent gravity based on the actual installation attitude of the aircraft decelerator; initial liquid level conditions are set, where a zero initial liquid level function indicates no lubricating oil initially; the first phase is set as liquid lubricating oil, and the second phase is set as air, with the density, viscosity, and corresponding viscosity models for lubricating oil and air respectively set; the surface tension model is enabled, and surface tension and contact angle are set.

[0033] After completing the physical model and boundary condition settings, the total simulation time, time step mode, Courant number, overall grid size, and process file saving format and frequency are set. Gas-liquid two-phase flow simulations are then performed under various preset operating conditions. These preset operating conditions can correspond to different gear speeds, flight attitudes, inlet flow rates, or other operating states requiring evaluation; specific operating condition combinations are determined based on the design requirements of the aircraft gearbox.

[0034] After the calculation for each preset working condition is completed, export the time-domain data of the return oil port flow rate corresponding to that working condition. Total inbound traffic and the internal oil phase volume fraction field The return oil port flow rate time-domain data describes the change of return oil port flow rate over time; the inlet total flow rate represents the total flow rate of lubricating oil entering the reducer, which can be set to a constant value in this embodiment; the internal oil phase volume fraction field describes the proportion of oil phase at any spatial location and any storage time inside the reducer. For the return oil port flow rate time-domain data used to calculate the return oil response time, the start time of the corresponding process is used as the timing starting point when evaluating the start-up or acceleration process; when evaluating the process of switching from a lower stable return oil level to a higher stable return oil level, the operating condition switching time is used as the timing starting point, and the return oil port flow rate time-domain data from the timing starting point to the period when the return oil port flow rate value reaches the target stable return oil level is obtained.

[0035] In addition to the numerical simulation methods mentioned above, multiphase flow simulation can also employ the lattice Boltzmann method, the finite volume VOF method, the smooth particle hydrodynamic method, or the moving particle hydrodynamic method, etc.; the time-domain data of the return oil port flow rate can also be obtained from experimental measurements.

[0036] Step S200: Based on the time-domain data of the return oil port flow rate, a sliding window dual criterion is used to identify the stable return oil stage corresponding to each preset working condition.

[0037] Specifically, such as Figure 3 As shown, time windows are constructed by taking the time-domain data of the return oil port flow rate under each preset operating condition according to a preset time window length. These time windows are then moved sequentially along the time direction according to a preset sliding step size, resulting in multiple time windows arranged in chronological order. Adjacent time windows may partially overlap or be joined end-to-end, specifically determined by the preset sliding step size. Return oil port flow rate data is extracted from each time window as the window return oil port flow rate data for the corresponding time window. The window average return oil port flow rate and the standard deviation of the return oil port flow rate for each time window are calculated. For the first... The average return oil flow rate within a given time window is expressed as follows:

[0038] in, Indicates the first The average return oil flow rate corresponding to each time window; Indicates the first The number of return oil flow data points corresponding to each time window; Indicates the first The first time window corresponds to the first One window return oil inlet flow data point; The sequence number of the return oil flow data point in the window; This is the time window number.

[0039] Furthermore, the first The standard deviation of the return oil flow rate corresponding to each time window is expressed as follows:

[0040] in, Indicates the first The standard deviation of the return oil port flow rate corresponding to each time window; the standard deviation of the return oil port flow rate is used as the fluctuation degree of the return oil port flow rate within the time window to reflect the dispersion of the return oil port flow rate within the time window.

[0041] After obtaining the average return flow rate of adjacent time windows and the fluctuation degree of the return flow rate of each time window, a joint judgment is made using the window mean change criterion and the internal fluctuation criterion. The two criteria are as follows:

[0042]

[0043] in, Indicates the threshold for the rate of change of the window mean; Indicates the window fluctuation threshold; Indicates the previous time window The average return port flow rate within the window is used. The threshold can be preset based on the data sampling frequency, flow pulsation characteristics, and evaluation accuracy requirements. To avoid the relative change criterion being unable to be calculated due to the average return port flow rate being zero or close to zero in the initial startup phase, the dual criterion calculation is only performed when the average return port flow rate within the current time window and the previous time window are both greater than the preset non-zero flow rate judgment value; time windows that do not meet this condition are not considered candidate windows for the stable return port phase.

[0044] When the above two criteria are simultaneously met for M consecutive time windows, and the return oil flow rate value in the time domain data of the return oil flow rate no longer continuously increases or decreases over time after the start time of the time window that first meets the above two criteria, the aircraft gearbox is determined to have entered the stable return oil phase. Here, M represents the number of time windows that continuously meet the stability conditions. The start time of the first time window in the consecutive time windows that first meet the above two criteria is determined as the start time of the stable return oil phase. In this embodiment, each preset operating condition is simulated or measured independently. Therefore, under the premise of meeting the above trend conditions, the time interval between the start time of the stable return oil phase and the end time of the simulation or measurement of the corresponding preset operating condition is determined as the stable return oil phase.

[0045] Step S200, by simultaneously examining the change in the average return oil flow rate of adjacent time windows and the fluctuation in the return oil flow rate of a single time window, can avoid selecting a stable range based solely on a single flow trend or manual observation, and reduce the possibility of transient pulsations caused by gear meshing oil slinging being misidentified as a stable state, thus enabling different working conditions to adopt a unified stable stage determination logic.

[0046] Step S300: Based on the stable oil return stage, the total inlet flow rate, and the internal oil phase volume fraction field, calculate the oil return performance evaluation index corresponding to each preset working condition. The oil return performance evaluation index includes the stable average oil return rate, the spatial oil accumulation rate, the oil return fluctuation coefficient, and the oil return response time.

[0047] After determining the stable oil return stage corresponding to each preset operating condition, the stable average oil return rate, space oil accumulation rate, oil return fluctuation coefficient, and oil return response time are calculated respectively. The four indicators describe the oil return performance from the aspects of sufficient oil return, internal oil retention, flow fluctuation in the stable stage, and the oil return establishment speed after startup, acceleration, or switching from a lower stable oil return level to a higher stable oil return level.

[0048] For the stable average return oil rate: Extract the return oil inlet flow rate data within the stable return oil stage from the time-domain data of the return oil inlet flow rate to obtain the stable stage return oil inlet flow rate data, and average the stable stage return oil inlet flow rate data to obtain the average stable stage return oil inlet flow rate:

[0049] in, This represents the average flow rate at the return port during the stable phase. This indicates the number of data points representing the return oil flow rate data during the stable phase; This indicates the first of the return oil flow data in the stable phase. One return oil inlet flow data point; This indicates the data point number in the return oil flow data during the stable phase.

[0050] The steady-state average return rate is calculated based on the average return flow rate at the return port and the total inlet flow rate during the steady-state phase.

[0051] in, This indicates the stable average oil return rate; This indicates the total inlet flow rate of the aircraft speed reducer.

[0052] In this embodiment, the aircraft gearbox is equipped with a lubricating oil inlet, so the total flow rate of the inlet is used as the reference flow rate of the lubricating oil entering the aircraft gearbox. The closer the stable average oil return rate is to 1, the higher the proportion of lubricating oil entering the gearbox is discharged from the oil return port during the stable phase; when the stable average oil return rate is significantly low, it can be further combined with the space oil accumulation rate to determine whether there is internal oil accumulation or the oil return channel is restricted.

[0053] Regarding the space oil accumulation rate: In order to incorporate the information on the oil space distribution inside the reducer into the evaluation of oil return performance, the internal oil volume at each storage time is calculated based on the internal oil phase volume fraction field. For the first... At each storage time, the internal oil volume is expressed as:

[0054] in, Indicates time The corresponding internal oil volume of the aircraft gearbox; Indicates the number of computational units in the internal fluid domain; Indicates the first Each computing unit at time... The oil phase volume fraction; Indicates the first The volume of each computing unit; Indicates the calculation unit number; This indicates the sequence number of the oil phase field preservation time during the stable oil return phase.

[0055] The average internal oil volume during the stable oil return phase is obtained by averaging the internal oil volume at each storage time within the stable phase.

[0056] in, This represents the average internal oil accumulation volume during the stable phase. This indicates the number of moments in the internal oil phase volume fraction field preserved during the stable oil return phase.

[0057] The spatial oil accumulation rate is calculated based on the average internal oil accumulation volume and the effective volume of the internal fluid domain during the steady-state phase.

[0058] in, Indicates the oil accumulation rate in the space; This indicates the effective volume of the internal fluid domain of an aircraft gearbox. A higher space oil accumulation rate indicates a higher proportion of oil remaining in the internal fluid domain during the stable oil return phase; a lower space oil accumulation rate indicates a lower degree of internal oil accumulation. This indicator transforms the internal oil phase volume fraction field from qualitative cloud map information into a quantitative parameter that can be used for comparison under different operating conditions and structural schemes.

[0059] Regarding the return oil fluctuation coefficient: During the stable return oil phase, periodic pulsations may still occur due to gear oil slinging, gas-liquid entrainment, or local flow blockage. Therefore, the return oil fluctuation coefficient is calculated based on the return oil port flow rate data and the average return oil port flow rate during the stable phase.

[0060] in, This represents the return oil fluctuation coefficient; the smaller the return oil fluctuation coefficient, the lower the dispersion of each return oil port flow value in the stable phase return oil port flow data relative to the average return oil port flow value in the stable phase.

[0061] Regarding the return oil response time: For the return oil establishment process after aircraft deceleration starts, accelerates, or switches from a lower stable return oil level to a higher stable return oil level, a preset proportion of the average return oil port flow rate during the stable phase is used as the return oil response judgment benchmark. The flow rate values ​​of each return oil port in the time domain data are compared with the judgment benchmark, and the moment when the flow rate first reaches or exceeds the judgment benchmark is defined as the return oil response time.

[0062] in, Indicates the return oil response time; Indicates the time during the simulation or measurement process; This indicates the change of the return oil port flow rate value over time in the time domain data of the return oil port flow rate; This represents the response judgment ratio coefficient. The response judgment ratio coefficient can be set according to the evaluation accuracy requirements, preferably 0.90 to 0.98, for example, 0.95. In this embodiment, the starting time of the aircraft decelerator's start-up, acceleration, or switch from a lower stable oil return level to a higher stable oil return level is taken as the timing zero point, where the time is the relative time from the timing zero point; the oil return response time determination method is used for the process of establishing the oil return port flow from low to high. For the operating condition where the oil return port flow switches from a higher stable level to a lower stable level, the existing descent-type response time determination method in the art can be used to obtain the corresponding oil return response time. The smaller the oil return response time, the shorter the time required for the above-mentioned oil return establishment process to reach a near-stable oil return state.

[0063] By using the above four evaluation indicators, we can avoid evaluating the overall oil return performance solely based on the return port flow rate or a single return rate, and ensure that the degree of oil discharge during the stable phase, the oil accumulation in the internal space, the flow fluctuation during the stable phase, and the dynamic response process are all included in the same evaluation system.

[0064] Step S400: Calculate the comprehensive oil return performance index corresponding to each preset working condition based on the oil return performance evaluation index corresponding to each preset working condition.

[0065] For the same aircraft gearbox structure, the first For each preset operating condition, the stable average oil return rate, spatial oil accumulation rate, oil return fluctuation coefficient, and oil return response time obtained in step S300 are first processed to be dimensionless. The corresponding dimensionless indices can be expressed as:

[0066]

[0067]

[0068]

[0069] in, Indicates the preset operating condition sequence number; , , and They represent the first Stable average oil return rate, space oil accumulation rate, oil return fluctuation coefficient, and oil return response time under preset working conditions; , , and These represent the corresponding dimensionless indices; Indicates the first The target oil return rate for a preset working condition is preferably 1. Indicates the first The maximum allowable oil accumulation rate in a preset working condition; Indicates the first The upper limit of the allowable oil return fluctuation coefficient for a preset working condition; Indicates the first The upper limit of the allowable oil return response time for each preset operating condition. The above target value and allowable upper limit can be determined based on the gearbox design requirements, test calibration results, engineering experience, or evaluation requirements for different flight conditions.

[0070] After performing dimensionless processing, the four dimensionless indices are weighted to obtain the first... The comprehensive oil return performance index corresponding to each preset working condition:

[0071] in, Indicates the first The comprehensive oil return performance index corresponding to each preset working condition; , , and These represent the weights of the indicators corresponding to the stable average oil return rate, spatial oil accumulation rate, oil return fluctuation coefficient, and oil return response time, respectively. The weights of each indicator satisfy the following:

[0072] in, , , and The sum is 1, and the specific value can be set according to the evaluation focus of different types of aircraft gearboxes. Since the stable average oil return rate is a positive indicator, while the space oil accumulation rate, oil return fluctuation coefficient, and oil return response time are negative indicators, the corresponding negative evaluation terms are used in the comprehensive oil return performance index. According to the unified evaluation rules, when the dimensionless index corresponding to the space oil accumulation rate, oil return fluctuation coefficient, or oil return response time is not greater than 1, it is calculated according to the negative evaluation terms in the comprehensive oil return performance index formula; when any of the aforementioned dimensionless indexes is greater than 1, the negative evaluation term corresponding to that index is determined to be 0, that is, the negative evaluation term is truncated to a non-negative value and is no longer calculated according to the formula.

[0073] This step converts four types of oil return performance evaluation indicators with different physical meanings and dimensions into a single-condition comprehensive quantity under the same scale, thereby facilitating comparison of the same aircraft gearbox structure under different preset conditions.

[0074] Step S500: Calculate the multi-condition comprehensive oil return performance index of the aircraft reducer based on the comprehensive oil return performance index corresponding to each preset working condition and the corresponding working condition weight.

[0075] Assuming the same aircraft gearbox structure has a total of The preset operating conditions are determined based on their importance, the proportion of flight mission duration, the proportion of speed range, or the test evaluation requirements. Each preset working condition is assigned a corresponding working condition weight, and the comprehensive oil return performance index of each preset working condition is weighted to obtain the multi-working-condition comprehensive oil return performance index:

[0076] in, This represents the multi-condition comprehensive oil return performance index of the aforementioned aircraft gearbox structure; Indicates the total number of preset operating conditions; Indicates the preset operating condition sequence number; Indicates the first Each preset working condition corresponds to a working condition weight. The working condition weights satisfy the following:

[0077] The sum of the weights for each operating condition is 1. The multi-operating condition comprehensive oil return performance index is used to form an overall evaluation quantity for the same reducer structure while preserving the differences in the importance of each operating condition; when the comprehensive oil return performance index corresponding to a certain preset operating condition is significantly lower than that of other preset operating conditions, this operating condition can also be used as the key analysis object when determining the direction of subsequent structural optimization.

[0078] Step S600: Determine the structural optimization direction of the aircraft gearbox based on the oil return performance evaluation index, the comprehensive oil return performance index, and the multi-condition comprehensive oil return performance index.

[0079] Specifically, for the first For each preset operating condition, the stable average oil return rate, spatial oil accumulation rate, oil return fluctuation coefficient, and oil return response time are compared with the corresponding target oil return rate, spatial oil accumulation rate upper limit, oil return fluctuation coefficient upper limit, and oil return response time upper limit. Various anomaly determination relationships include:

[0080]

[0081]

[0082]

[0083] When the stable average oil return rate is lower than the target oil return rate, the condition is identified as insufficient overall oil return capacity; when the space oil accumulation rate exceeds the allowable upper limit, the condition is identified as abnormal internal oil accumulation; when the oil return fluctuation coefficient exceeds the allowable upper limit, the condition is identified as abnormal pulsation in the oil return process; when the oil return response time exceeds the allowable upper limit, the condition is identified as delayed oil return response.

[0084] Based on the comparison results of the above indicators, the direction of structural optimization is determined. In the first scenario, when the stable average oil return rate is lower than the target oil return rate and the space oil accumulation rate is higher than the allowable upper limit, it is determined that the oil return capacity is insufficient and accompanied by significant internal oil accumulation. The corresponding structural optimization directions include the oil return port cross-section, the oil return channel cross-section, the local resistance of the oil return channel, and the location of the oil return port. In the second scenario, when the stable average oil return rate is not lower than the target oil return rate but the space oil accumulation rate is higher than the allowable upper limit, it is determined that the overall oil return volume meets the target but there is still a large amount of stagnant oil inside. The corresponding structural optimization directions include the bottom guide structure of the cavity, the guide groove, the guide rib, and the cavity wall inclination angle. In the third scenario, when the oil return fluctuation coefficient is higher than the corresponding allowable upper limit, it is determined that the flow pulsation at the oil return port is too large during the stable oil return stage. The corresponding oil return structure optimization directions include the oil return port cross-section, the transition of the guide channel cross-section, and the cavity structure near the oil return port. Simultaneously, nozzle flow distribution can be used as a supply parameter related to the oil return process for collaborative optimization. In the fourth scenario, when the oil return response time is higher than the corresponding allowable upper limit, it is determined that the oil return establishment process is delayed after starting, accelerating, or switching from low to high operating conditions. The corresponding structural optimization directions include the guide path from the oil collection area to the oil return port, the height of the oil return port, the position of the oil return port, and the guide structure that is conducive to the rapid collection of oil.

[0085] Furthermore, when the stable average oil return rate is lower than the target oil return rate but the spatial oil accumulation rate does not exceed the allowable upper limit, the boundary conditions of the oil return port, the outlet pressure setting, the cross-sectional area of ​​the oil return port, and the local flow resistance near the oil return port can be prioritized as the inspection objects to distinguish between situations such as restricted outlet flow and unreasonable numerical boundary condition settings. This judgment can serve as a supplementary analysis path beyond the first scenario.

[0086] For multiple preset operating conditions of the same aircraft gearbox structure, the comprehensive oil return performance index of each preset operating condition is further compared. When the comprehensive oil return performance index of a certain preset operating condition is significantly lower than that of other operating conditions, the operating condition is identified as the key optimization operating condition, and the main sources of problems are determined by combining the stable average oil return rate, space oil accumulation rate, oil return fluctuation coefficient and oil return response time of the operating condition.

[0087] Simultaneously, a lower limit for the comprehensive oil return performance index under multiple operating conditions can be set, and the following formula can be used to determine whether the aircraft gearbox structure belongs to the overall optimization object under multiple operating conditions:

[0088] in, Indicates the comprehensive oil return performance index under multiple operating conditions; This indicates the lower limit of the allowable comprehensive oil return performance index under multiple operating conditions. The determination can be made based on design objectives, test calibration results, engineering experience, or evaluation results of similar aircraft gearbox structures. When the comprehensive oil return performance index under multiple operating conditions is lower than the aforementioned lower limit, the aircraft gearbox structure is identified as an object requiring oil return structure optimization.

[0089] This step establishes a correspondence between single-condition evaluation indicators, single-condition comprehensive oil return performance index, and multi-condition comprehensive oil return performance index and specific structural parts, so that the evaluation results can be further transformed into actionable structural optimization directions.

[0090] Step S700: Adjust the oil return structure parameters of the aircraft reducer according to the structural optimization direction.

[0091] Based on the structural optimization direction obtained in step S600, the corresponding oil return structure parameters are adjusted. In this embodiment, the adjustment of the oil return structure parameters can be completed in the three-dimensional digital model of the aircraft gearbox; the corresponding structural processing or modification of the physical aircraft gearbox can be implemented using conventional design and processing methods in the field based on the adjusted oil return structure parameters. For cases where the stable average oil return rate is lower than the target oil return rate and the spatial oil accumulation rate is higher than the allowable upper limit, the cross-sectional area of ​​the oil return port can be increased, the cross-section of the oil return channel can be optimized, the local resistance of the oil return channel can be reduced, or the position of the oil return port can be adjusted to address the situation where insufficient overall oil drainage and internal oil accumulation coexist.

[0092] For situations where the stable average oil return rate is not lower than the target oil return rate but the space oil accumulation rate is higher than the allowable upper limit, the bottom guide structure of the cavity can be optimized, oil guide grooves and oil guide ribs can be set or adjusted, and the cavity wall inclination angle can be improved so that the internal oil collection path is arranged towards the oil return port.

[0093] For cases where the return oil fluctuation coefficient exceeds the allowable upper limit, the cross-sectional area of ​​the return oil port can be adjusted, the transition of the guide oil channel section can be optimized, or the cavity structure near the return oil port can be adjusted. Simultaneously, the nozzle flow distribution can be optimized as needed. For cases where the return oil response time exceeds the allowable upper limit, the guide path from the oil collection area to the return oil port can be shortened, the height and position of the return oil port can be adjusted, or a guide structure that facilitates rapid oil collection can be added.

[0094] For cases where the stable average oil return rate is lower than the target oil return rate but the space oil accumulation rate does not exceed the allowable upper limit, the boundary conditions of the oil return port, the outlet pressure setting, the cross-sectional area of ​​the oil return port, and the local flow resistance near the oil return port can be checked first. Once it is confirmed that the problem is due to structural factors, the corresponding oil return port or local channel structure can be adjusted.

[0095] Based on the above-described implementation methods, this embodiment also provides a quantitative evaluation and optimization system for the oil return performance of aircraft gearboxes. For example... Figure 4As shown, the system includes a data acquisition module, a stable oil return stage identification module, an oil return performance evaluation index calculation module, a comprehensive oil return performance index calculation module, a multi-condition comprehensive oil return performance index calculation module, a structural optimization direction determination module, and an oil return structure parameter adjustment module.

[0096] The system comprises the following modules: a data acquisition module for step S100; a stable oil return stage identification module for step S200; an oil return performance evaluation index calculation module for step S300; a comprehensive oil return performance index calculation module for step S400; a multi-condition comprehensive oil return performance index calculation module for step S500; a structural optimization direction determination module for step S600; and an oil return structure parameter adjustment module for determining the oil return structure parameters to be adjusted based on the structural optimization direction output in step S600, and updating the corresponding parameters in the three-dimensional digital model of the aircraft gearbox. The modules sequentially call the data or evaluation results generated in the preceding steps according to the data transfer relationships from steps S100 to S700, forming a system processing flow corresponding to the above method.

[0097] The above embodiments use numerical simulation of gas-liquid two-phase flow to obtain time-domain data of return oil inlet flow rate and internal oil phase volume fraction field as the main examples, but it does not limit the data to be generated by specific software or specific numerical methods. Other multiphase flow solution methods or experimental measurement methods that can obtain the same physical quantities can be processed according to the above rules for stable return oil stage identification, evaluation index calculation, comprehensive return oil performance index calculation, and structural optimization.

[0098] The specific embodiments of the present invention have been described above. For those skilled in the art, without departing from the technical concept of the present invention, the time window, judgment threshold, target value, allowable upper limit, index weight, and operating condition weight can be set according to the specific aircraft gearbox structure, operating condition range, and evaluation requirements.

[0099] According to another aspect of the embodiments of this application, an electronic device is also provided, including a processor and a memory, wherein the processor is configured to implement the steps of the method when executing a computer program stored in the memory.

[0100] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0101] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0102] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0103] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0104] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes, characterized in that, Includes the following steps: Acquire time-domain data of return oil flow, total inlet flow, and internal oil phase volume fraction field of the aircraft gearbox under multiple preset operating conditions; Based on the time-domain data of the return oil port flow rate, a sliding window dual criterion is used to identify the stable return oil stage corresponding to each preset working condition. Based on the stable oil return stage, the total inlet flow rate, and the internal oil phase volume fraction field, calculate the oil return performance evaluation index corresponding to each preset working condition. The oil return performance evaluation index includes the stable average oil return rate, the space oil accumulation rate, the oil return fluctuation coefficient, and the oil return response time. Based on the oil return performance evaluation index corresponding to each preset working condition, calculate the comprehensive oil return performance index corresponding to each preset working condition. Based on the comprehensive oil return performance index corresponding to each preset working condition and the corresponding working condition weight, the multi-working-condition comprehensive oil return performance index of the aircraft gearbox is calculated. Based on the oil return performance evaluation indicators, the comprehensive oil return performance index, and the multi-condition comprehensive oil return performance index, the structural optimization direction of the aircraft gearbox is determined. Adjust the oil return structure parameters of the aircraft gearbox according to the aforementioned structural optimization direction.

2. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 1, characterized in that, Methods for obtaining time-domain data of return oil flow, total inlet flow, and internal oil phase volume fraction field of an aircraft gearbox under multiple preset operating conditions include: Establish a three-dimensional model of the aircraft decelerator; Extract the internal fluid domain of the aircraft deceleration unit from the three-dimensional model; A numerical simulation model of gas-liquid two-phase flow is established based on the internal fluid domain. The gas-liquid two-phase flow numerical simulation model was used to simulate the gas-liquid two-phase flow under multiple preset working conditions, and the simulation results corresponding to each preset working condition were obtained. The time-domain data of the return oil port flow rate, the total inlet flow rate, and the internal oil phase volume fraction field are obtained from the simulation results corresponding to each preset working condition.

3. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 2, characterized in that, The method for identifying the stable oil return stage corresponding to each preset operating condition using a sliding window dual-criteria method includes: The time-domain data of the return oil port flow rate is divided into multiple consecutive time windows according to a preset time window length. Extract the return oil port flow data within each time window as the window return oil port flow data for the corresponding time window, and perform average processing on the window return oil port flow data to obtain the window average return oil port flow corresponding to each time window. Based on the return oil flow rate data and the average return oil flow rate of each time window, calculate the fluctuation degree of the return oil flow rate of each time window. Based on the degree of change between the average return oil flow rate of two adjacent time windows and the degree of fluctuation of the return oil flow rate of each time window, multiple time windows are screened using dual criteria. When the dual criteria are met in multiple consecutive time windows, and the return oil flow rate value in the time domain data of the return oil flow rate no longer continuously increases or decreases over time after the start time of the time window when the dual criteria are first met, the stable return oil stage is determined.

4. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 3, characterized in that, The method for calculating the stable average oil return rate includes: Extract the return oil port flow rate data during the stable return oil phase from the time domain data of the return oil port flow rate to obtain the stable phase return oil port flow rate data. The average flow rate of the return oil port during the stable phase is obtained by averaging the return oil port flow rate during the stable phase. The stable average return rate is calculated based on the average return flow rate at the return port during the stable phase and the total inlet flow rate.

5. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 3, characterized in that, The method for calculating the space oil accumulation rate includes: The internal oil volume at each storage time during the stable oil return stage is calculated based on the internal oil phase volume fraction field. The average internal oil volume at each storage time during the stable oil return phase is averaged to obtain the average internal oil accumulation volume during the stable phase. The spatial oil accumulation rate is calculated based on the average internal oil accumulation volume during the stable phase and the effective volume of the internal fluid domain.

6. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 4, characterized in that, The calculation method for the return oil fluctuation coefficient includes: Based on the return oil flow rate data of the stable phase and the average return oil flow rate of the stable phase, the dispersion of the return oil flow rate within the stable return oil phase is calculated. The return oil fluctuation coefficient is calculated based on the dispersion of the return oil flow rate and the average return oil flow rate during the stable phase.

7. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 4, characterized in that, The calculation of the return oil response time includes: The return oil response judgment criterion is determined based on the average flow rate at the return oil port during the stable phase. Compare each return oil port flow rate value in the time domain data of the return oil port flow rate with the return oil response judgment benchmark to determine the moment when the return oil port flow rate value in the time domain data of the return oil port flow rate first reaches the return oil response judgment benchmark. The time is defined as the oil return response time.

8. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 1, characterized in that, The methods for calculating the comprehensive oil return performance index and the multi-condition comprehensive oil return performance index include: The stable average oil return rate, spatial oil accumulation rate, oil return fluctuation coefficient and oil return response time corresponding to each preset working condition are respectively processed into dimensionless evaluation indexes corresponding to each preset working condition. The comprehensive oil return performance index corresponding to each preset working condition is obtained by weighted calculation based on the dimensionless evaluation index corresponding to each preset working condition. The weight of each preset operating condition is determined based on its importance, the proportion of flight mission duration, the proportion of speed range, or the test evaluation requirements. The multi-condition comprehensive oil return performance index is obtained by weighting the comprehensive oil return performance index corresponding to each preset working condition and the corresponding working condition weight.

9. The method for quantitative evaluation and optimization of oil return performance of aircraft gearboxes as described in claim 1, characterized in that, The method for determining the structural optimization direction of the aircraft gearbox and adjusting the oil return structure parameters of the aircraft gearbox includes: Based on the comprehensive oil return performance index corresponding to each preset working condition and the comprehensive oil return performance index of the multi-working condition, the working condition to be optimized is determined. The stable average oil return rate, space oil accumulation rate, oil return fluctuation coefficient, and oil return response time corresponding to the working condition to be optimized are compared with the corresponding target oil return rate, the upper limit of the space oil accumulation rate, the upper limit of the oil return fluctuation coefficient, and the upper limit of the oil return response time, respectively, to obtain the index comparison results. The optimization conditions corresponding to the working condition to be optimized are determined based on the comparison results of the aforementioned indicators, wherein: The first optimization condition is: the stable average oil return rate is lower than the corresponding target oil return rate, and the space oil accumulation rate is higher than the corresponding upper limit of the space oil accumulation rate. The second optimization condition is: the stable average oil return rate is not lower than the corresponding target oil return rate, and the space oil accumulation rate is higher than the corresponding upper limit of the space oil accumulation rate. The third optimization condition is: the return oil fluctuation coefficient is higher than the corresponding allowable upper limit of the return oil fluctuation coefficient; The fourth optimization condition is: the oil return response time is higher than the corresponding upper limit of the allowable oil return response time; When the first optimization condition is met, at least one first oil return structure parameter to be adjusted is determined from the oil return port cross section, oil return channel cross section, local structure of oil return channel, and oil return port position. When the second optimization condition is met, at least one second oil return structure parameter to be adjusted is determined from the bottom guide structure of the cavity, the oil guide groove, the oil guide rib and the inclination angle of the cavity wall. When the third optimization condition is met, at least one third oil return structure parameter to be adjusted is determined from the oil return port cross section, the transition of the oil guide channel cross section, the cavity structure near the oil return port, and the nozzle flow distribution. When the fourth optimization condition is met, at least one fourth return oil structure parameter to be adjusted is determined from the following: the guide path from the oil collection area to the return oil port, the return oil port height, the return oil port position, and the guide structure. The oil return structure of the aircraft gearbox is adjusted according to at least one of the first, second, third, and fourth oil return structure parameters to be adjusted.

10. A quantitative evaluation and optimization system for the oil return performance of an aircraft gearbox, characterized in that, include: The data acquisition module is used to acquire time-domain data of return oil flow, total inlet flow, and internal oil phase volume fraction field of the aircraft gearbox under multiple preset operating conditions. The stable oil return stage identification module is used to identify the stable oil return stage corresponding to each preset working condition based on the time domain data of the oil return port flow rate using a sliding window dual criterion. The oil return performance evaluation index calculation module is used to calculate the oil return performance evaluation index corresponding to each preset working condition based on the stable oil return stage, the total inlet flow rate, and the internal oil phase volume fraction field. The oil return performance evaluation index includes the stable average oil return rate, the spatial oil accumulation rate, the oil return fluctuation coefficient, and the oil return response time. The comprehensive oil return performance index calculation module is used to calculate the comprehensive oil return performance index corresponding to each preset working condition based on the oil return performance evaluation index corresponding to each preset working condition. The multi-condition comprehensive oil return performance index calculation module is used to calculate the multi-condition comprehensive oil return performance index of the aircraft gearbox based on the comprehensive oil return performance index corresponding to each preset condition and the corresponding condition weight. The structural optimization direction determination module is used to determine the structural optimization direction of the aircraft gearbox based on the oil return performance evaluation index, the comprehensive oil return performance index and the multi-condition comprehensive oil return performance index corresponding to each preset working condition. The oil return structure parameter adjustment module is used to determine the oil return structure parameters to be adjusted according to the structure optimization direction.

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