Elliptical gears are widely used in the fields of aerospace and automation equipment due to their excellent variable speed characteristics and compact structure. To reveal the control mechanism of phase angle on the motion characteristics of two-stage elliptical gear transmission system (TSEGTS) and improve its stability under variable speed loading, this paper proposes a modeling method that integrates two-dimensional tooth profile envelope method and image processing technology to extract tooth profile and analyze system motion characteristics. By introducing the fluctuation coefficient as a stability indicator, the system studied the effects of phase angle, input speed, and load torque on angular velocity, angular acceleration, and torque. The results indicate that the phase angle has a significant periodic modulation effect on the motion characteristics of the system. The angular velocity and acceleration of intermediate shaft B and output shaft C, as well as the torque of output shaft C, exhibit a distribution with 90 degrees as the axis of symmetry within the range of 0 degrees-180 degrees. The average torque fluctuation coefficients of input shaft A and intermediate shaft B in the range of 0 degrees-90 degrees are 4.02 and 3.03, respectively, which are significantly higher than the 3.46 and 1.99 coefficients in the range of 90 degrees-180 degrees. As the input speed increases from 5 pi to 20 pi rad/s, the torque fluctuation coefficients of shafts A, B, and C increase from 2.87, 1.37, and 0.53 to 22.54, 14.19, and 8.43, respectively. When the load torque increases from 2 to 8 Nm, the fluctuation coefficients of the three axes decrease from 11.33, 7.12, and 4.22 to 3.51, 1.91, and 1.05, respectively. The increase in load torque effectively suppresses fluctuations and improves meshing stability. The experimental and simulation results are consistent, verifying the effectiveness of the model. The research results can provide theoretical basis for parameter optimization and dynamic performance control of TSEGTS.

Gas-bearing-supported gear–rotor systems are widely used in precision measurement equipment, where vibration performance is critically influenced by the bearing support characteristics. In this study, a nonlinear dynamic model of a gear–rotor system supported by gas bearings is established, in which the bending–torsional coupling effect and the bearing support stiffness are explicitly taken into account. Based on isothermal compressible gas lubrication theory, the Reynolds equation is solved using a finite difference scheme to obtain the gas film pressure distribution of the gas bearing. The influences of rotational speed from 500 to 1500 r·min−1 and gas film clearance from 7 to 11 μm on the gas film pressure characteristics and the equivalent support stiffness are investigated. The equivalent stiffness is subsequently incorporated into the dynamic equations of the gear–rotor system to analyze its vibration responses. The results show that increasing rotational speed significantly enhances the gas film pressure and enlarges the high-pressure region along the circumferential direction due to strengthened hydrodynamic effects. In contrast, an increase in gas film clearance leads to a pronounced reduction in pressure magnitude and load-carrying capacity, resulting in a nonlinear decrease in the equivalent support stiffness. Dynamic analysis indicates that rotational speed plays a dominant role in the vibration behavior of the gas-bearing-supported gear–rotor system, while variations in gas bearing stiffness substantially affect the vibration response characteristics.

To systematically clarify the migration and evolution mechanisms of metallic particles in the solid-liquid-gas three-phase flow field of a helicopter intermediate reducer under splash lubrication, this study innovatively develops a three-phase numerical model based on the CFD-DPM framework, and establishes a high-precision oil-churning visualization test rig for experimental validation via high-speed imaging technology. Under the baseline operating condition (gear rotational speed of 1500 r/min, dimensionless oil immersion depth lambda(h) = 6.78), the effects of multiple hydrodynamic forces (gravity, pressure gradient force, virtual mass force, Magnus lift, and Saffman lift) on particle trajectories and dynamic responses are comprehensively evaluated. Meanwhile, comparative analyses are conducted to quantify the regulatory effects of particle density (intrinsic property variation) and initial release location (meshing region, spallation region, sidewall/bottom) on migration behavior. Numerical results reveal that the pressure gradient force and virtual mass force dominate macroscopic particle transport: the former prolongs the quasi-steady stage by 40%-50%, while the latter accelerates particle velocity decay to near-zero within 0.3-0.5 s. In contrast, the Saffman lift and Magnus lift play secondary roles, mainly inducing high-frequency velocity fluctuations (velocity perturbation amplitude <= 15% for Saffman lift) and exhibiting strong medium dependence (Magnus lift doubles particle migration distance in the gas phase but is negligible in the oil phase). Increasing particle inertia significantly weakens flow-following capability, and the particle velocity response intensity follows the order: meshing region > spallation region > sidewall/bottom. Visualization experiments verify a complete particle transport cycle inside the gearbox (extrusion from the meshing region-airborne flight-wall collision-gravity-driven return), which is in good agreement with numerical predictions. Further experimental results show that increasing the rotational speed from 100 to 400 r/min significantly enhances oil splash height and particle adhesion on the top and side walls. At a high immersion depth (lambda(h) = 11.86), intense turbulent splashing leads to global dispersion of the oil-particle mixture; at a low immersion depth (lambda(h) = 1.70), particle motion is dominated by local entrainment with weak wall retention. Additionally, as the particle volume fraction increases from 0.1%, 0.5%, 1.0%, the oil-particle mixture exhibits a pronounced thickening effect, suppressing oil splashing and enhancing particle deposition. These findings provide robust theoretical support and technical guidance for the optimization of splash lubrication design and reliability assessment of helicopter transmission systems.

This article investigates the multiphysics coupling mechanism among Dynamic Thermal Elastohydrodynamic Lubrication (DTEHL), Load Tooth Contact Analysis (LTCA), and system dynamics in a Closed Differential Herringbone Gear Transmission System (CDHGTS). Based on gear meshing theory, ring gear flexibility, and rough surface contact, a dynamic contact lubrication model is developed using thermoelastic fluid dynamic lubrication theory. A gear heat transfer model integrating heat transfer and flexible deformation is established to capture dynamic thermal variations at each ring gear node. By coupling the DTEHL model, heat transfer model, and LTCA model, a nonlinear dynamic model incorporating flexible-tribo coupling is constructed. The nonlinear dynamic response of the CDHGTS under DTEHL conditions is analyzed, focusing on the influence of ring gear flexibility on system vibration. Furthermore, nonlinear dynamic behavior induced by ring gear flexibility, friction coefficient, and damping coefficient is examined. The proposed model is validated through bench vibration experiments. The study refines dynamic modeling and analysis methods for herringbone gears, offering theoretical guidance for evaluating the impact of coupled engineering factors on gear dynamics.

Non-circular planetary gear systems exhibit significant time-varying transmission characteristics, which can easily trigger complex nonlinear dynamic responses during operation, adversely affecting vibration stability. This paper develops a 36-degree-of-freedom bending-torsional coupling nonlinear dynamic model for 4-6 order non-circular planetary gear systems, incorporating multiple excitation factors, including time-varying mesh stiffness (TVMS), meshing damping, backlash, friction, and comprehensive transmission error. A TVMS calculation method applicable to both internal and external meshing pairs is proposed based on curvature radius theory. The system's nonlinear dynamic equations are solved numerically using the Runge-Kutta method. Nonlinear dynamic analyses, including bifurcation diagrams, time histories, phase diagrams, and Poincare sections, were employed to systematically investigate the influence of key parameters-rotational speed, eccentricity, damping, and backlash on the system response. Multiscale methods were further used to examine their effects on main resonance characteristics. Quantitative results show that the system transitions from periodic motion to 2-periodic and chaotic states as rotational speed increases, with peak vibration amplitudes rising from 1.12 m/s 2 to over 5.6 m/s 2 across tested speeds. Eccentricity critically affects dynamic behavior: under identical speed conditions, the external meshing pair enters a quasi-periodic state at an eccentricity of 0.22, earlier than the internal pair at 0.32. Increasing tooth flank clearance can trigger chaotic responses, whereas enhancing system damping reduces peak amplitudes by up to 32%45%, significantly improving operational stability at medium to high speeds. Finally, a prototype test platform was established to validate the model. Experimental results and theoretical predictions show good agreement, peak to peak comparison has good consistency, confirming that the model effectively captures the system's main dynamic behavior. These findings elucidate the unique nonlinear dynamics of non-circular planetary gear systems, providing a quantifiable theoretical basis for structural optimization and engineering applications.

To elucidate the energy dissipation mechanism of a Standard straight bevel gear transmission system under splash lubrication, this article proposes a churning power loss prediction model tailored to such systems. This model decomposes the total power loss into three parts, namely circumferential resistance, end face stirring, and extrusion loss in the meshing area, and combines the control volume method with the bevel gear slicing method to achieve an engineering approximate quasi analytical model of stirring power loss. A transparent visualization test rig for churning power loss was developed, and systematic experiments were conducted over a range of rotational speeds (1,000-4,000 r/min), the dimensionless immersion depth (defined as the ratio between oil level and gear pitch radius) (0.5-1.5), and lubricant dynamic viscosities (0.0085-0.21228 Pa & centerdot;s). The results show that, as the speed increases from 1,000 r/min to 4,000 r/min, the total churning power loss rises from 135 W to 5524 W; meanwhile, the proportion of end-face drag loss decreases from 51.6% to 38.7%, whereas the contribution of squeeze loss in the meshing region increases from 48.2% to 61.3%. At 2,000 r/min, when the dimensionless immersion depth increases from 0.5 to 1.5, the total power loss increases from 283 W to 1559 W, and the share of mesh-region squeeze loss rises from 44.5% to 58%, becoming the dominant dissipation component. Under high-speed conditions of 4,000 r/min and dimensionless immersion depth of 1.0, increasing the lubricant viscosity from 0.0085 to 0.21228 Pa & centerdot;s causes the total power loss to increase from 774 W to 8176 W, with the dominant loss mechanism gradually transitioning from viscous shear to hydrodynamic squeeze. The theoretical predictions and experimental data trends are roughly consistent, confirming the accuracy and applicability of the proposed model under a wide range of operating conditions, and providing a quantitative basis for energy optimization of high-performance bevel gear transmission systems.

Aerospace cylindrical roller bearings often operate under high-speed and heavy-load conditions. Its dynamic behavior has a significant impact on bearing performance. Previous dynamic studies have focused mainly on individual cylindrical roller bearings, neglecting the dynamic performance and mechanical properties within the bearing tester system environment. This paper establishes a dynamic finite element simulation model using ANSYS/LS-DYNA under the operating conditions of a bearing tester. Considering bearing speeds and radial loads, explicit dynamic finite element simulations of cylindrical roller bearings are conducted under bearing tester conditions to study the variation rule of contact stress and vibration acceleration. The feasibility of the simulation is verified through theoretical calculations. The simulation results indicate that bearing speed and radial load have a significant impact on the dynamic characteristics of cylindrical roller bearings. As the bearing speed increases, the mean contact stress and roller vibration acceleration of the rollers and components increase accordingly. The mean equivalent stress in the bearing outer ring’s load-bearing area increases by 21.2

Three-point contact ball bearings, due to its high stability in high-speed and heavy-load environments, are widely used in aerospace transmission systems. Under different working conditions, the dynamic characteristics of the bearing can change significantly, which directly affect the accuracy and service life of the bearing. Therefore, the dynamic performance of three-point contact ball bearings were discussed considering the impact of different working conditions. A simulation mesh model was established using Hypermesh software then the finite element method based on explicit dynamics was used for dynamic simulation. The influence factors like working speed, axial load, and cage pocket clearance on the dynamic performance were simulated, in which the rules of roller speed, contact stress of various components, and roller vibration acceleration, were analyzed. Through comparative analysis of the simulation results, the following conclusions were drawn: Axial load has a significant effect on the stress changes in the components of the three-point contact ball bearing. As the axial load increases, the maximum stress in the inner and outer rings increases by approximately 180

Fiber-reinforced composites have excellent mechanical properties, like high specific strength and specific modulus, etc. Laminates made from a combination of single-layer materials have a wide range of applications in aerospace transmission components because of the ability to meet the design requirement of lightweight. Conventional strength theories tend to predict laminates strength by establishing strength criterion from tensile, compression and shear strengths obtained from unidirectional slab tests. However, due to the significant anisotropy of the composites, in-situ effects indicate that sublayers of the same thickness and layup angle exhibit different matrix strengths in unidirectional slabs and in laminates, which resulting in errors of laminates strength between calculated and tested values. Moreover, it is costly and complex to test the laminates for each lay-up option to obtain its strength parameters. In response to the above issues, T800/WC502 material laminate with lay-up method of [0/45/90/-45/0]7 which is for the use of aero-engine case, was taken as an example to analyze the mechanical properties. The impact of in-situ effect was taken into account when establishing strength criterion. The mechanical properties and strength of this laminate were analyzed using macro-mechanical methods and finite element methods. Then the laminate was subjected to tensile tests in accordance with the test standards. Results of finite element analysis (FEA) were compared with the test data to analyze the accuracy of calculation. The results show that the FEA results have less error with the test data after taking into account the in-situ strength. This method provides a reference for subsequent research on the mechanical properties of aero-engine case.

The design process for bearings typically involves design, simulation and testing. However, the influence of paired bearings and actual support is not considered during the design process, which results in an incomplete match between design parameter considerations and tester parameters. This, in turn, reduces the efficiency of the design process. In addressing these issues, this paper focuses on cylindrical roller bearings as the research object, conducting dynamics investigation and comparison under single bearing and tester systems. Utilising the theory of finite element analysis, finite element dynamics models of cylindrical roller bearings under single bearing and tester systems are established, respectively. The dynamic characteristic parameters of stress, contact force, roller deflection angle and vibration acceleration are extracted to obtain the vibration characteristics of the bearings. The differences in the dynamic characteristics of cylindrical roller bearings under the same load and rotational speed in the two working conditions are then compared. The results demonstrate that with an increase in load and rotational speed, there is an increase in stress, contact force, vibration acceleration and maximum deflection angle of cylindrical roller bearing. Besides, it is evident that the dynamic parameters in the tester system are larger than those in the single-bearing system. However, the average deflection angle shows a decreasing trend with the increase of rotational speed and an increasing trend with the increase of load.

Study on the effects of backlash, friction, and rotational speed on the nonlinear bifurcation characteristics of Non-Orthogonal Misaligned Face Gear Power Split-Flow Transmission System (NOMFGPSFTS), aiming to provide theoretical basis and technical guidance for improving power to weight ratio, prolonging service life, and ensuring the reliability of the power transmission mechanism of innovative helicopters, ships and automobiles. An 11 degree of freedom (DOF), bending, torsion and axis coupling nonlinear dynamic model is established by using the lumped mass method. The model uses Load Tooth Contact Analysis(LTCA) method to calculate the meshing stiffness of Non-Orthogonal Misaligned Face Gear (NOMFG), and combines the key nonlinear elements, including gear tooth surface friction, backlash, support stiffness and transmission error, to facilitate an accurate representation of the system dynamics. The system's dynamic differential equations are solved using the RungeKutta algorithm, and the system's nonlinear characteristics are demonstrated through time domain diagrams, Fast Fourier Transform (FFT) spectrograms, phase plane diagrams, Poincare maps and Maximum Lyapunov Exponent diagrams. Bifurcation diagrams are used to further reveal the effects of backlash, rotational speed, and friction coefficient on the system's nonlinear behavior. The study finds that with the increase of dimensionless backlash, the system transits from periodic-1 motion to chaotic motion, and may evolve into periodic-2 motion, showing obvious nonlinear vibrations. With the increase of rotating speed, the system transits from periodic-2 motion to chaotic motion, and finally realizes periodic-1 motion. With the increase of friction coefficient, the chaotic region of the system decreases. Finally, the correctness of the theoretical model is verified by experiments, which provides a theoretical basis for the stability study of the system.

Due to factors such as eccentric load and error, the gear will produce cracks and pitting corrosion and other failure modes, resulting in the change of the dynamic characteristics of the two-stage herringbone gear transmission system (TSHBGTS), which will have a serious impact on the stability of the operation of the high-torque engine. To investigate the impact of crack-pitting coupling on the vibration characteristics of the TVMS, a dynamic model with 48 degrees of freedom was developed. This model considers various factors such as errors, time-varying meshing stiffness (TVMS), torsional stiffness, support stiffness, tooth friction, and repulsion slot variations. The potential energy method is employed to calculate the TVMS for each herringbone gear pair in the system, accounting for the effects of crack-pitting coupling and changes in the retractor slot parameter. The dynamic model is solved using the Runge–Kutta numerical integration method, enabling the analysis of the system’s time-domain and frequency-domain responses under varying degrees of crack-pitting coupling. The vibration testing explores how different degrees of crack-pitting coupling affect the system’s time-frequency response characteristics. The results reveal that the system’s stiffness decreases with an increasing degree of crack-pitting coupling, initially dominated by pitting and eventually by crack influence. The time-domain response characteristics exhibit shock behavior that varies with the meshing cycle, becoming more pronounced with increased crack-pitting coupling. Additionally, the frequency-domain response is characterized by side frequency signals near the octave frequency, indicative of crack-pitting coupling effects. This behavior exacerbates as the crack-pitting coupling intensifies, leading to deteriorating vibration stability. Comparative analysis of test and theoretical data demonstrates consistency in trends, affirming the model’s accuracy. The research results are of great significance for the dynamic stability and quality evaluation of TVMS.

To investigate the vibration characteristics of the herringbone gear planetary transmission system (HGPTS) with crack-pitting coupling factors, a 55-DOF bending-torsion-axle-pendulum (BTAP) coupled dynamics model of the drive system is established. This model accounts for the effects of errors, time-varying mesh stiffness (TVMS), torsional stiffness, support stiffness, and retract groove. In the model, the TVMS of the sun and planetary herringbone gear pair is calculated, considering crack-pitting coupling using the potential energy method and the slicing method. The dynamics model is solved using the Runge-Kutta numerical integration method, yielding the time-domain and frequency-domain responses of the drive system under different degrees of crack-pitting coupling. The analysis focuses on the vibration response of the system due to changes in crack-pitting coupling. Additionally, vibration tests are performed to assess the impact of different crack-pitting parameters on the system's time-frequency response characteristics. The results show that the time-domain response of the system, influenced by crack-pitting coupling, is characterized by periodic impact behavior, which becomes more pronounced as the degree of crack-pitting coupling increases. In the frequency domain, the system's response exhibits failure frequency phenomena, with noticeable side-frequency signals near the octave frequency. These signals worsen as crack-pitting coupling increases, leading to a deterioration in the vibration stability of the system. A comparison between experimental data and theoretical results shows good consistency, validating the correctness of the model. This research provides a theoretical foundation for fault diagnosis as well as the operation and maintenance of the system.

The lubrication performance of cylindrical roller bearings is directly linked to their operational accuracy and lifespan. Therefore, experimental testing is essential before deployment. However, lubrication analysis is often carried out on individual cylindrical roller bearings, ignoring the effect of the tester. Therefore, based on computational fluid dynamics (CFD), a simulation model for oil jet lubrication of cylindrical roller bearings is established in single bearing system and tester system. The effects of different oil supply speeds, rotational speeds, and radial loads on the lubrication characteristics of bearings in the two systems are investigated in this paper. The accuracy of the simulation method is verified by comparison to the experiment. The research shows that when the oil supply speed increases, the average oil volume fraction inside the bearings in the tester system is higher than that in the single bearing system. The bearing temperature shows a linear decrease in the two systems. As the speed increases, the decreasing trend of the average oil volume fraction in the tester system differs from that in the single bearing system. The bearing temperature rises and exceeds that of the single bearing system. When the load increases, the temperature rise of the cylindrical roller bearings in the tester system is greater than that in the single bearing system.

To extend the time between the overhauls of helicopters, a novel collaborative methodology that takes into account uncertain misalignment errors by considering the shape and performance of the gear is built. Firstly, the digital characteristics of contact patterns, such as the reference point and direction angle, are extracted. Secondly, an optimization model calculates the equivalent misalignment by minimizing deviations in the reference point and direction angle between two contact patterns. This equivalent misalignment accounts for uncertainty misalignment errors introduced by complex gear support deformation. Thirdly, the ease-off is utilized to derive the pinion target surface that can sustain meshing performance under an equivalent misalignment, similar to the original gear in real conditions. This way it integrates with the optimization theory for flank reconstruction to redesign the pinion surface. Simulations reveal that the critical digital characteristics of the contact path on the original gear under the equivalent misalignment mirror those of the original gear in real conditions. Moreover, the surface parameters of the redesigned pinion result in an identical surface under a different equivalent misalignment, maintaining similar contact and dynamic performance. This proposed collaborative design approach, considering the shape and performance while accounting for uncertain misalignment errors through ease-off, greatly improves the gear transmission behavior.

The gear components are among the core fundamental parts of wind turbine gearboxes, and their operating condition significantly affects the performance of the gearbox transmission chain and even the entire wind turbine. This article derives the calculation method for the time-varying mesh stiffness (TVMS) of cracked herringbone gears based on the slice method. Additionally, a dynamic model with multiple degrees of freedom, considering factors such as relief grooves and errors, is established for the cracked herringbone gear planetary system (HGPS) with a bending-torsion-axis pendulum (BTAP) based on the lumped parameter method. The vibration curves of the system with varying cracks are obtained by solving the model using the Runge-Kutta method. Furthermore, a test rig is set up, and vibration tests are conducted. The results show that when cracks appear in the sun gear, the TVMS of the meshing pairs, both inside and outside the system, decreases. As the crack worsens, the fluctuation of the TVMS diminishes. Cracks induce periodic impact behaviors in the system, with an impact time of the fault cycle of T = 0.012 s. Significant sidebands appear near the mesh harmonic frequency, fm = 750 Hz, and the vibration trajectory of the gear becomes chaotic. As the cracks intensify, the vibration of the system becomes more pronounced. Experimental results are consistent with the theoretical results, verifying the accuracy of the established model and the feasibility of the simulation.

To reduce the vibration of the Coaxial Helicopter Main Transmission System(CHMTS)considering both level and vertical flight conditions,a vibration evaluation and optimization model for the CHMTS was built.The vibration simulation model of the CHMTS was set up by gear dynamics theory and loaded contact analysis.For better evaluation of the system vibration,a vibra-tion evaluation method for the CHMTS was established by the G1 method-variation coefficient method.A hybrid Gravitational Search Algorithm-Simulated Annealing(GSA-SA)algorithm was combined to balance convergence speed and searching accuracy.The principle test was con-ducted to prove the accuracy of theoretical method,in which the maximum relative error is 16.26％.The optional results show that the vibration of the optimized transmission system decreases significantly,in which the maximum reduction of key vibration indicators reaches more than 20％.The theoretical results have been compared to the experiment to verify the effectiveness of the vibration optimization method.The proposed method could be extended to other fields.

This research delved into the effects of topological modification on the nonlinear bifurcation properties of herringbone gear transmission system (HGTS). A model utilizing the potential energy method was initially developed to analyze the time-varying meshing stiffness (TVMS) of a herringbone gear following topological modification. Additionally, a dynamic model of a bending-torsion-axis-pendulum (BTAP) coupling of HGTS with 24 degrees of freedom (DOF) was established, which took into account various factors such as topological modification, meshing errors, TVMS, damping, backlash, and bearing clearance. The model employed the Runge-Kutta method to assess the pre-topological and post-topological modification nonlinear vibration responses and bifurcation characteristic, with a specific emphasis on backlash, and speed variations. The bifurcation diagram and maximum lyapunov exponent (MLE) graph were employed to elucidate these changes. Supplementary studies utilizing time domain diagram, frequency domain diagram, phase plane diagram, poincaré map analyses provided a comprehensive understanding of the HGTS’s nonlinear dynamics. The findings indicate that while the fundamental vibration and bifurcation trends persist post-topological modification, local bifurcation and vibration responses exhibit improvements. Specifically, an increase in backlash leads to a transition from single-periodic to multi-periodic, and then to chaotic regimes, the topological modification improves in reverting some chaotic behaviors to periodic, thereby reducing the extent of chaos. Increased rotational speeds result in periodic-chaotic-periodic sequences, but topological modification shifts bifurcation points, reducing chaos. Comparisons of experimental and theoretical data corroborate the model’s accuracy, demonstrating consistent trends.

The complex flow field in the high-speed gearbox affects the transmission efficiency and perfor-mance of the transmission system by affecting the gear oil injection lubrication characteristics.Therefore,it is necessary to carry out research on the two-phase flow field and lubrication characteristics of high-speed gear oil injection considering the complex flow field of high-speed gear box and the baffle structure.Based on the com-putational fluid dynamics method,a two-phase flow field analysis model of high-speed helical gear oil injection lubrication is established,and the two-phase flow field distribution characteristics are analyzed.On this basis,the effects of injection parameters such as injection speed,injection angle,axial injection angle,and gear baffle on the injection lubrication characteristics are further studied.The results show that the oil on the surface of high-speed helical gear inclines to one side.By increasing the injection speed or adding the positive axial angle,the oil deflection and the lubrication effect can be improved.The gear baffle plays a role in guiding the oil,and the setting of axial baffle is conducive to increasing the oil on the tooth surface.This study provides a basis for the study of two-phase flow field distribution characteristics of high-speed gearboxes and the optimization de-sign of oil injection lubrication.

High-speed gears are crucial transmission components found in airplanes and other systems, and they are maintained primarily through oil injection. However, due to their high operating speeds and the influence of oil injection settings, gear surface lubrication efficacy is frequently insufficient, compromising the transmission system’s precision, durability, and safety. Currently, the parameter choices for oil injection in high-speed gears mostly rely on empirical judgment, which results in significant time and resource expenses. This study focuses on one pair of internal meshing gears within a specific aircraft gearbox, establishing an oil injection lubrication model for high-speed internal meshing gears using the computational fluid dynamics (CFD) approach. This research provides insights and references for optimizing oil injection parameters and improving lubrication efficiency in high-speed internal meshing gear systems by examining the dynamic characteristics of internal meshing wind resistance in addition to the effects of injection tube position, angle, and speed on lubrication performance.