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NONLINEAR DYNAMIC ANALYSIS OF OIL-FREE TURBOMACHINERY

无油涡轮机非线性动态分析

基本信息

批准号：
EP/I029184/1
负责人：
Philip Bonello
金额：
$ 36.91万
依托单位：
University of Manchester
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FI029184%2F1
关键词：
NONLINEAR DYNAMIC ANALYSIS OIL FREE

项目摘要

Oil-free turbomachinery is an emerging technology defined as high speed rotating machinery that operates without oil-lubricated rotor supports. The term is generally understood to refer to gas-bearing technology, in particular, foil-air bearings. Such bearings support the shaft by means of an air cushion bounded by a flexible foil structure. The introduction of the foil structure resolves the problems associated with the very tight radial clearance required by a plain air bearing. With a foil-air bearing, while the shaft is stationary, there is either a slight clearance or a preload between shaft and bearing. As the shaft turns, a pressure is generated, which pushes the foil boundary away, allowing the shaft to become completely airborne. A solid lubricant coating on the shaft and/or top foil allows for the brief rubbing interval during start-up and shutdown. Recent technological breakthroughs in the USA in solid lubricant technology will enable the widespread use of such bearings in turbomachinery, particularly gas turbine machinery. This has resulted in intensive research in oil-free turbomachinery motivated by its technological and environmental benefits for both military and civil applications (e.g. turbochargers that run up to 180,000rpm and engines for small aircraft). As stated by NASA, the foremost challenge for this technology is the design of an oil-free turbine engine to power 21st century aircraft .Foil-air bearings, like conventional oil bearings, are nonlinear elements that are capable of introducing undesirable nonlinear effects into the dynamic response of the system. These effects may involve sudden jumps in the vibration amplitude, non-synchronous vibration and self-excited vibration. These effects exacerbate vibration and introduce fatigue. Hence, to guarantee structural integrity, the deployment of these bearings in practical machinery necessitates rotordynamic analysis that takes account of the bearing nonlinearity. The ability to make reliable quantitative predictions of such effects enables the engineer to account for/mitigate them in the design. Moreover, such analysis provides the basis of a much-needed knowledge database for in-service monitoring. However, such calculations are hampered by the prohibitive computational cost introduced by the complexity of the bearing model. Consequently, dynamic analysis has so far been restricted to a highly simplified rotordynamic system. The proposed project researches novel methods that enable the efficient nonlinear dynamic analysis of practical oil-free turbomachinery. These methods will be experimentally validated in a study that provides a much-needed insight into the nonlinear dynamics of such systems. The deliverables of this project will be:i. A suite of computer software algorithms for efficient nonlinear dynamic analysis based on three novel approaches (Galerkin reduction, Harmonic Balance, System Identification). ii. An original-design test-rig for experimental validation of the computational methods.iii. A report on the validation of the methods, focussing on both computational and experimental issues.The proposed research is novel since: (a) It will give the UK a foothold in oil-free turbomachinery technology, raising the UK's scientific profile - such research has to date been confined mainly to the US; (b) It will research the prediction of the nonlinear dynamics of practical oil-free turbomachinery (e.g. an oil-free turbocharger); (c) It will do so through the three novel approaches mentioned above; (d) It will produce an original-design test-rig for the validation of the methods developed and investigation of nonlinear phenomena.The work will be carried out by a post-doctoral researcher over a period of three years.

无油透平机械是一种新兴技术，其定义为无油润滑转子支承的高速旋转机械。该术语通常被理解为指气体轴承技术，特别是箔式空气轴承。这种轴承通过由柔性箔结构约束的气垫来支撑轴。箔片结构的引入解决了与平坦空气轴承所需的非常紧密的径向游隙相关的问题。对于铝箔空气轴承，当轴是静止的时，轴和轴承之间要么有微小的间隙，要么有预紧力。当轴转动时，会产生一个压力，将箔片边界推开，使轴完全悬浮在空中。轴和/或顶箔上的固体润滑剂涂层允许在启动和关闭期间有短暂的摩擦间隔。美国最近在固体润滑剂技术方面的技术突破将使这种轴承在透平机械，特别是燃气轮机机械中得到广泛使用。这导致了对无油涡轮机械的密集研究，其动机是军事和民用应用的技术和环境效益(例如，高达18万转/分的涡轮增压机和小型飞机的发动机)。根据NASA的说法，这项技术面临的最大挑战是设计一种为21世纪的飞机提供动力的无油涡轮发动机。油气轴承和传统的石油轴承一样，都是非线性元件，能够在系统的动态响应中引入不良的非线性效应。这些影响可能涉及振动幅度的突然跳跃、非同步振动和自激振动。这些影响会加剧振动，并导致疲劳。因此，为了保证结构的完整性，在实际机械中部署这些轴承时，必须进行考虑轴承非线性的转子动力学分析。对这些影响做出可靠的定量预测的能力使工程师能够在设计中考虑/缓解这些影响。此外，这种分析为在职监测提供了急需的知识数据库的基础。然而，轴承模型的复杂性带来了高昂的计算成本，阻碍了这样的计算。因此，到目前为止，动力学分析仅限于高度简化的转子动力学系统。该项目研究的新方法能够对实用的无油透平机械进行有效的非线性动力学分析。这些方法将在一项研究中得到实验验证，该研究为此类系统的非线性动力学提供了亟需的洞察力。这个项目的成果将是：i.一套基于三种新方法(伽辽金约化、谐波平衡、系统辨识)的高效非线性动力学分析的计算机软件算法。二、用于对计算方法进行实验验证的原始设计的试验台。一份关于方法验证的报告，重点关注计算和实验问题。拟议的研究是新颖的，因为：(A)它将使英国在无油涡轮机械技术方面站稳脚跟，提高英国的科学形象--此类研究迄今主要局限于美国；(B)它将研究实用无油涡轮机械(例如，无油涡轮增压器)的非线性动力学预测；(C)它将通过上述三种新方法做到这一点；(D)它将制作一个原始设计的试验台，用于验证所开发的方法和研究非线性现象。这项工作将由一名博士后研究员进行，为期三年。