微型高速驱动系统气体轴承的织构动力润滑及主动控制研究

Some requirements of micro high-speed drive systems include high load-carrying capacity, low friction, and high stability for self-acting gas-lubricated bearings; and therefore macro/micro multi-scale texture dynamic lubrication and active control of the bearing components of next generation drive systems will be thoroughly investigated. A self-adaptive multi-objective optimization method will be proposed to implement 3D optimization of the textured structure of macro/micro multi-scale self-acting gas-lubricated bearings, and consequently the optimal design parameters of the texturing will be obtained. The optimization problem of multi-objective characteristics, with special attention to the power loss and stability, will be modeled. As a result, the design criteria of macro/micro multi-scale optimization for self-acting gas-lubricated bearings will be presented. Special attention will be given to the rarefaction and interface effect for micro-scale gas-lubricated bearings. The lubrication performance of macro/micro multi-scale self-acting bearings with 3D textured surfaces will be investigated by hybrid modeling of modifying molecule gas film lubrication and micro-scale gas dynamics. The model for solving the complete dynamic coefficients of nonlinear characteristics of optimized multi-scale self-acting bearings will be established by considering the compliance of pivot of tilting pad, and the corresponding numerical method will be proposed. As a result, the law of enhancing nonlinear stability of self-acting compressible gas-lubricated bearings will be revealed. The valuable control strategy for the textured bearings will be proposed based on the working principle of piezoelectric actuators. As well, hybrid control law for time delay control of the textured bearings is presented. Experiments will be conducted to validate the theoretical model of lubrication between textured rotors and textured stators and hybrid contol law. The present research will provide valuable fundamental theory and key technical issues to the design of the key component in micro high-speed drive systems.

本项目围绕作为新一代微型高速驱动系统支承部件的气体轴承，针对其承载力高、摩擦小和高稳定性的要求，进行宏、微尺度织构动力润滑及主动控制研究。针对可压缩气体润滑的自作用动压轴承，提出一种自适应变步长多目标优化方法，进行3D宏、微尺度气体轴承的织构优化，得到最优的织构设计参数，在综合考虑系统功耗和稳定性的基础上，提出自作用气体轴承的优化设计准则；通过考虑微尺度时的气体稀薄和界面效应，采用修正气体分子薄膜润滑模型的方法并结合微观气体动力学，研究宏、微尺度的3D织构化轴承的动力润滑机理；计入可倾瓦支点的顺应性，提出织构化气体轴承完整非线性动力学特性系数的模型化描述及求解方法，揭示自作用气体轴承的非线性稳定性规律；提出压电作动器驱动的动压气体轴承的有效控制策略，构建织构化轴承时滞控制的复合控制律，通过实验验证织构动力润滑模型和复合控制律，为微型高速驱动系统支承部件的设计提供有价值的基础理论和核心技术。

本项目围绕作为新一代微型高速/超高速驱动系统支承部件的气体轴承，针对其承载力高、摩擦小和高稳定性的要求，对高速/超高速工况下微型驱动系统中高速支承部件的织构优化、宏微尺度动力润滑与主动控制进行了研究。主要内容包括：（1）建立了具有球形凹坑织构的固定瓦-可倾瓦组合气体轴承润滑模型，以承载力最大和摩擦力最小作为优化目标函数，通过对最大深度、单元面积率和周向织构率等优化变量进行优化，实现了织构几何参数的优选。（2）针对微型高速气体轴承，基于Galerkin加权余量法，研究了具有稀薄效应的微气体轴承的静态特性，以及努森数、轴承数、偏心率等参数对微气体轴承静态特性的影响规律。（3）将动态偏心率和动态偏位角表示为含周期性扰动的复数形式，得到了在复平面内动态气膜压力及动态气膜厚度表达式，在此基础上运用偏导数法，研究了稀薄效应对动态刚度和动态阻尼的影响规律。（4）考虑到温度和压力对气膜粘度、密度、比热容、热传导率和气流速度的影响，构建了微气体轴承的热润滑模型，研究了环境温度、转速、偏心率和间隙等对微型气体轴承气膜三维温度分布和静态性能的影响规律。（5）针对微型涡轮发动机工作中典型的温度环境，给出了考虑热蠕动时的一阶滑移边界条件，研究了在极大温差下微气体轴承的热蠕动效应。（6）基于精细积分法，构造了求解含双时滞的轴向槽动压气体轴承-柔性转子系统非线性动力响应的求解方法，研究了时滞量对轴向槽动压气体轴承-转子系统动力学行为的影响规律。（7）基于压电作动器和比例-微分控制，建立了具有主动润滑的气体轴承-转子系统动力学模型，在此基础上，通过主动控制策略有效地减小了系统的非线性响应幅值。（8）在100 kW微型燃气轮机模拟转子试验台上开展了试验研究，试验结果可用于评估微型燃气轮机真实轴承-转子系统在额定转速范围内工作的多项性能指标。本项目开展的研究具有重要的科学意义和广阔的军民两用应用前景。