基于可控电磁支承的水下航行器推进轴系-壳体系统振动控制方法研究

Water lubricated rubber bearings are commonly used in the shafting system of underwater vehicles in order to reduce vibration transmission. However, lubrication of rubber bearings at low speeds is usually inadequate, which will deteriorate vibration of shafting systems and even generate high frequency noises with standing features. Consequently, sound quality or stealth of underwater vehicles is severely affected. In this investigation, the controllable electromagnetic shaft support (CESS) is proposed to replace the intermediate water lubricated rubber bearing. Introducing noncontact shaft support to eliminate abnormal noises as well as reduce shaft vibrations is the need of engineering applications and it is hence of real significance. Three aspects are considered to investigate associated theoretical problems: (1) The role of CESS in the control of the impedance of shaft support. The aim is to clarify the influence of stiffness and damping of CESS on the vibration characteristics of the coupled system as well as the shafting support impedance, vibration transmission and hull responses; (2) The role of CESS in the control of friction induced shaft vibrations. The aim is to clarify the influence of electromagnetic force control of CESS on the rubber bearing friction force and its induced vibration responses; (3) The role of CESS in the control of transmission of propeller vibrations. The aim is to clarify the influence of the interface force control of CESS on the vibration responses of the shaft and hull structures as well as the redistribution characteristics of propeller vibration transmission. In addition, theoretical results and control effectiveness will be verified through an experimental system to exhibit the feasibility of the proposed scenario in reducing shafting noises and to establish new methods for the design of low-noise propulsion shafting systems.

水下航行器的推进轴系常用水润滑橡胶轴承减小振动传递，然而橡胶轴承在低速运行条件下由于润滑不良会导致轴系振动加剧或产生特征稳定的高频噪声，严重影响水下航行器的声品质或声隐身性能。本项目针对实际需求，考虑以可控电磁支承代替部分橡胶轴承，通过引入非接触轴系支承减小轴系-壳体振动，消除异常噪声，研究具有现实意义。项目拟从三个方面研究基本理论问题：①电磁支承对轴系支承阻抗的控制作用，明确电磁支承刚度和阻尼对耦合系统振动特征、轴系支承阻抗、轴系振动传递以及壳体振动响应的影响规律；②电磁支承对轴系摩擦诱导响应的控制作用，明确电磁力控制对橡胶轴承摩擦力及其诱导响应的影响规律；③电磁支承对螺旋桨振动传递的控制作用，研究轴系支承力控制对螺旋桨振动传递的再分配特性，获得电磁支承动态力控制对轴系及壳体振动的影响规律。同时，结合实验平台，验证理论方法和控制效果，明确方案的可行性，为低噪声推进轴系设计提供新方法。

本项目针对水下航行器螺旋桨推进系统噪声，研究轴系横向振动传递控制方法，为有效衰减螺旋桨激励通过轴系支承向壳体传递提供新的途径。项目首次在螺旋桨-轴系-壳体系统中引入可控电磁支承，建立了耦合系统动力学模型及主动控制方法，明确了电磁力控制对轴承支承面阻抗及界面摩擦力的影响规律，在大尺度螺旋桨-轴系-壳体实验系统中验证了可控电磁支承的有效性，结果表明中高频振动特征可衰减50%以上；首次提出并联杆式主动支承及相应的多通道控制方法，将传统支承的面传递降为并联杆的有限点传递，抑制螺旋桨激励通过轴系艉支承向壳体的传递，并大尺度螺旋桨-轴系-壳体实验系统中验证其有效性，结果表明线谱特征衰减可达80%以上；从全局控制角度出发，为同时考虑轴向、横向振动传递控制以及轴系动力学时变特性，提出基于动力学在线建模的自适应振动控制新算法，使控制性能更加稳定，实用性更强。大尺度螺旋桨-轴系-壳体系统的实验结果表明，在不同转速下，控制算法均能显著降低线谱特征，幅值衰减50%-90%。本项目的理论和技术成果可应用于实际系统的振动控制，为水下航行器振动噪声控制提供支撑。

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