为研究环下润滑结构内部油膜迁移及流动特性,针对轴心射流收油环采用VOF (Volume of fluid)方法开展了数值计算,获得了收油环端面油膜动态形成过程,在分析流场特征的基础上,讨论了收油环运转工况及结构参数对内部油膜形态、滑油体积分...为研究环下润滑结构内部油膜迁移及流动特性,针对轴心射流收油环采用VOF (Volume of fluid)方法开展了数值计算,获得了收油环端面油膜动态形成过程,在分析流场特征的基础上,讨论了收油环运转工况及结构参数对内部油膜形态、滑油体积分数、油膜速度和供油孔输油能力的影响规律。结果表明:收油环端面油膜呈圆盘状迁移,边缘破碎形成油滴、油带甩至侧壁面,在供油孔内以“月牙形”分布加速流动,收油环端面油膜厚度随主轴转速增大而减小,随喷嘴流量上升而增加;提高转速降低了供油孔内滑油含量,使孔内油膜加速流动,孔内滑油含量随喷嘴流量的上升而增大,随供油孔径的增加而下降;喷嘴流量与供油孔径的改变对孔内流速影响较小;增加孔径与提高收油环转速可加强供油孔输运能力,8 kr/min下提高喷嘴流量使无量纲输油量Cq平均降低了40.71%,提高孔径使Cq最大提高了57.14%,转速的增加使Cq平均增加25.87%。展开更多
Under-race lubrication applied to the inter-shaft bearing of aeroengine is characterized by spray oil collection and oil delivery to the bearing via flow-path structure. Droplet splashing induced by the collision betw...Under-race lubrication applied to the inter-shaft bearing of aeroengine is characterized by spray oil collection and oil delivery to the bearing via flow-path structure. Droplet splashing induced by the collision between spray oil and the scoop as well as oil flowing characteristics in the flow-path influence bearing lubrication efficiency. In previous investigations, the spray oil collection and oil delivery analysis were separated, and the effect of droplet splashing on bearing lubrication efficiency was not considered. Moreover, time-varying characteristics of oil delivered to the bearing were not accounted for. This is caused by time variations of the circumferential position of rollers and under-race feed holes. To overcome these limitations, a numerical model which integrates the spray oil collection and oil delivery analysis is proposed in this paper. The model is embedded with the function of calculating the flow rate of splashing droplets and analyzing time-varying characteristics of the oil fed to the bearing. Furthermore, the numerical model is validated by experimental investigation. The proposed numerical model facilitates the accurate calculation of bearing lubrication efficiency as well as the design of an efficient lubrication structure.展开更多
As the load and working environment temperature increasing,high efficiency oil lubrication was urgently needed for the main bearing of aeroengine.However,the low oil capture efficiency of radial oil scoop affects the ...As the load and working environment temperature increasing,high efficiency oil lubrication was urgently needed for the main bearing of aeroengine.However,the low oil capture efficiency of radial oil scoop affects the application of under-race lubrication structure with radial oil collection.In this work,a novel design of curved blade oil scoop for under-race lubrication is proposed to improve the oil capture efficiency.First of all,the principle of relative velocity optimization is proposed by analyzing the collision process between blade and oil jet for theoretical research.Then,the theoretical curve equations of blade inlet under three different oil jet incidence conditions are solved.After that,the monotonicity of the theoretical curves is analyzed.The effects of rotation speed,oil jet velocity,eccentric distance of oil jet,and include angle of curve are analyzed.The location of the collision points of proposed theoretical curves are also been optimized.Finally,a transient Computational Fluid Dynamics(CFD)simulation of the novel oil scoop design was carried out.The simulation results show that the capture efficiency of curved blade oil scoop can be improved by 30%comparing to the traditional design.展开更多
文摘为研究环下润滑结构内部油膜迁移及流动特性,针对轴心射流收油环采用VOF (Volume of fluid)方法开展了数值计算,获得了收油环端面油膜动态形成过程,在分析流场特征的基础上,讨论了收油环运转工况及结构参数对内部油膜形态、滑油体积分数、油膜速度和供油孔输油能力的影响规律。结果表明:收油环端面油膜呈圆盘状迁移,边缘破碎形成油滴、油带甩至侧壁面,在供油孔内以“月牙形”分布加速流动,收油环端面油膜厚度随主轴转速增大而减小,随喷嘴流量上升而增加;提高转速降低了供油孔内滑油含量,使孔内油膜加速流动,孔内滑油含量随喷嘴流量的上升而增大,随供油孔径的增加而下降;喷嘴流量与供油孔径的改变对孔内流速影响较小;增加孔径与提高收油环转速可加强供油孔输运能力,8 kr/min下提高喷嘴流量使无量纲输油量Cq平均降低了40.71%,提高孔径使Cq最大提高了57.14%,转速的增加使Cq平均增加25.87%。
基金supported by the National Science and Technology Major Project(No.J2019-Ⅲ-0023-0067)the National Natural Science Foundation of China(No.51975475)the Fundamental Research Funds for the Central Universities(No.31020200503002)。
文摘Under-race lubrication applied to the inter-shaft bearing of aeroengine is characterized by spray oil collection and oil delivery to the bearing via flow-path structure. Droplet splashing induced by the collision between spray oil and the scoop as well as oil flowing characteristics in the flow-path influence bearing lubrication efficiency. In previous investigations, the spray oil collection and oil delivery analysis were separated, and the effect of droplet splashing on bearing lubrication efficiency was not considered. Moreover, time-varying characteristics of oil delivered to the bearing were not accounted for. This is caused by time variations of the circumferential position of rollers and under-race feed holes. To overcome these limitations, a numerical model which integrates the spray oil collection and oil delivery analysis is proposed in this paper. The model is embedded with the function of calculating the flow rate of splashing droplets and analyzing time-varying characteristics of the oil fed to the bearing. Furthermore, the numerical model is validated by experimental investigation. The proposed numerical model facilitates the accurate calculation of bearing lubrication efficiency as well as the design of an efficient lubrication structure.
文摘As the load and working environment temperature increasing,high efficiency oil lubrication was urgently needed for the main bearing of aeroengine.However,the low oil capture efficiency of radial oil scoop affects the application of under-race lubrication structure with radial oil collection.In this work,a novel design of curved blade oil scoop for under-race lubrication is proposed to improve the oil capture efficiency.First of all,the principle of relative velocity optimization is proposed by analyzing the collision process between blade and oil jet for theoretical research.Then,the theoretical curve equations of blade inlet under three different oil jet incidence conditions are solved.After that,the monotonicity of the theoretical curves is analyzed.The effects of rotation speed,oil jet velocity,eccentric distance of oil jet,and include angle of curve are analyzed.The location of the collision points of proposed theoretical curves are also been optimized.Finally,a transient Computational Fluid Dynamics(CFD)simulation of the novel oil scoop design was carried out.The simulation results show that the capture efficiency of curved blade oil scoop can be improved by 30%comparing to the traditional design.
