基于非线性刚度和平箔片凹陷的止推箔片轴承承载力优化

With the application of gas foil bearings in the field of micro turbomachinery more and more widely, high speed, single impeller and other work conditions ask higher and higher requirements of gas foil bearings performance. Nowadays, the limitation of wide application for gas foil bearings in high-speed micro turbomachinery filed is mainly focus on thrust bearing load capacity. The limitations of the existing bearing characteristics analysis model and algorithm are the main factors that affect the bearing maximum capacity design. Therefore, this aim of this project is to optimize the load capacity of gas thrust foil bearing based on structural non-linear stiffness and top foil sagging effect. First, a nonlinear stiffness model of bump foil and geometric model of tape region are derived with the consideration of bump foil real-time deformation. Based on this, a numerical model for foil thrust bearing performance calculation are established via coupling bump foil nonlinear stiffness model, tape height variation, top foil sagging and air film pressure, and the calculation method is studied. And then the low of bearing load capacity optimization design is obtained by studying the above factors on the bearing performance. Finally, the accuracy of the bearing model, and load capacity optimization design method are verified by experiments. This study will provide theoretical guidance for further industry application of gas thrust foil bearing.

随着气体箔片轴承在微型涡轮机械领域的应用越来越广泛，高转速、单叶轮等工作环境对气体箔片轴承的性能提出了越来越高的要求，目前制约气体箔片在高速微型涡轮机械的广泛应用主要集中在止推轴承的承载力上，而现有的轴承特性分析模型和算法的局限性是影响轴承最大承载力设计的主要因素。为此本项目拟开展气基于结构非线性刚度和平箔片凹陷效应的气体止推箔片轴承承载力优化研究。首先，建立轴承箔波纹非线性刚度数学模型和考虑波纹箔片变形的轴承楔形区域几何模型，并在此基础上进行考虑波纹箔片非线性刚度、楔形区域入口高度实时变化、平箔片凹陷和气膜压力耦合作用的轴承特性求解模型和相应的模型求解算法研究，然后通过研究上述因素对轴承特性的影响规律来指导轴承承载力优化设计方法。最后通过试验对来验证模型算法和承载力优化设计方法的准确性，为气体止推箔片轴承的进一步工程应用提供理论指导。

随着气体箔片轴承在微型涡轮机械领域的应用越来越广泛，高转速、单叶轮等工作环境对气体箔片轴承的性能提出了越来越高的要求，目前制约气体箔片在高速微型涡轮机械的广泛应用主要集中在止推轴承的承载力上，而影响推力轴承承载性能的因素不仅局限于轴承楔形区域入口高度、波纹箔片刚度设计、平箔片厚度等结构因素，还受到现有轴承特性分析模型和算法的局限性的制约。因此研究波纹箔片刚度特性，完善轴承建模分析和数值求解方法，揭示轴承承载性能随其结构参数变化规律，对提高轴承承载力性能具有重要意义。.本项目首先建立通过对单个波纹箔片进行刚度试验获得了轴承波纹箔片非线性刚度数学模型，并在此基础上进行考虑波纹箔片非线性刚度、楔形区域入口高度实时变化、平箔片凹陷和气膜压力耦合作用的轴承特性求解模型和相应的模型求解算法研究，然后通过研究上述因素对轴承特性的影响规律来指导轴承承载力优化设计方法。随后进行相关试验验证，结果表明：波纹箔片非线性刚度模型较经典恒定刚度模型更接近试验结果。此外，存在一个最佳轴承楔形区域入口高度，低于或者高于该高度，轴承的承载力都会下降，并且伴随着轴承摩擦功耗的上升。最后通过对平箔片凹陷特性仿真和试验研究发现，平箔片厚度较低会造成轴承楔形区域平箔片发生明显凹陷，导致轴承表面气膜压力分布不均，使得轴承承载力下降，造成摩擦功耗上升。.综上所述，通过本项目的研究，获得了较为精确的轴承建模和仿真分析方法，同时为获得最大轴承承载力，需要选取合适的轴承楔形区域入口高度和平箔片厚度。.