CAREER: Flow-Induced Instability in Rotating Machines: A Nonlinear Systems & Control Perspective

摘要：基于液膜滑动轴承的旋转机械由于转子-轴承系统中的机械-流体动力相互作用而引起的流致不稳定是非常敏感的。虽然流致不稳定性在80年前就已被发现，但它仍然是一个悬而未决的问题。这表明，两个最基本的问题仍然没有确定的答案：能否准确预测导致流动诱导不稳定的运行条件？如何减轻流动引起的不稳定性？问题的根本难点在于流动诱导的不稳定性是一种高度非线性、耦合的现象。该协会相信，系统与控制研究人员可以通过基于系统论的方法，为这个问题带来新的视角。为此，该项目的研究目标是：i)开发预测非线性机械-流体流动动态相互作用的模型；ii)开发非线性系统的稳定性分析工具以更好地表征流动诱导的不稳定性；iii)构思一种创新的传感器/执行器范例来控制不稳定性；以及iv)综合非线性反馈控制器。然而，路易斯安那州立大学的独特之处在于，它的数学系是全国为数不多的以数学控制理论为主要研究领域的系之一。为了利用这一优势，路易斯安那州立大学正在创建一个系统与控制小组，该小组将由四个工程部和数学系组成。该项目的教育计划将是这一努力的关键组成部分。该计划将包括四项活动，旨在吸引不同的学生群体，促进跨学科互动，并增加该领域吸引的学生的种族/种族多样性：i)开发急需的控制实验室课程，ii)为研究生开发系统与控制“调整”工作坊，iii)通过与当地HBCU的合作参与和指导少数族裔学生，以及iv)为初中生开发系统与控制夏令营。这项研究将吸引流体力学、摩擦学和系统与控制等领域的研究人员的兴趣。拟议的活动将通过为不确定的非线性系统和无限维系统引入创新的轴承概念和新的控制设计工具，促进这些领域内和跨领域的知识状况。更广泛的影响包括为少数族裔学生提供机会；扩大中学教育的覆盖面；扩大校园和全州学生获得系统和控制的机会；以及通过路易斯安那州立大学旋转机械中心的活动和行业合作伙伴关系进行传播和技术转让。

Abstract:Rotating machines based on fluid-film journal bearings are susceptible to flow-induced instability, which are caused by the mechanical-fluid flow dynamic interaction in the rotor-bearing system. Although flow-induced instability was discovered 80 years ago, it still remains an unsolved problem. This is indicative that the two most fundamental questions remain without definite answers: Can operating conditions that cause flow-induced instability be accurately predicted? How can flow-induced instability be mitigated? The essential difficulty of the problem is flow-induced instability is a highly nonlinear, coupled phenomenon. The PI believes systems & control researchers can bring a fresh perspective to the problem through a systems theory-based approach. To that end, the research objectives of this project are: i) develop models that predict the nonlinear mechanical-fluid flow dynamic interactions, ii) exploit stability analysis tools for nonlinear systems to better characterize flow-induced instability, iii) conceive an innovative sensor/actuator paradigm for controlling the instability, and iv) synthesize nonlinear feedback controllers.LSU, like many schools, has systems & control faculty and students throughout several engineering departments. However, LSU is unique in that its Math Department is one of the few in the nation whose main focus area is mathematical control theory. To take advantage of this strength, LSU is in the process of creating a Systems & Control Group that will comprise four Engineering departments and the Math Department. The educational plan of this project will be a key component in this effort. The plan will include four activities aimed at engaging a diverse community of students, promoting cross-disciplinary interactions, and increasing the ethnic/racial diversity of students attracted to the field: i) development of a much-needed control laboratory course, ii) development of a systems & control "tune-up" workshop for graduate students, iii) involvement and mentoring of minority students through collaborations with a local HBCU, and iv) development of a systems & control summer camp for middle and high school students.This research will attract the interest of researchers in the areas of fluid mechanics, tribology, and systems & control alike. The proposed activities will advance the state-of-knowledge within and across these fields by introducing innovative bearing concepts and new control design tools for uncertain nonlinear systems and infinite-dimensional systems. The broader impacts include opportunities for minority students; outreach towards secondary education; broadening the accessibility of systems & control to students across campus and across the state; and dissemination and technology transfer via the activities and industrial partnerships of the Center for Rotating Machinery under establishment at LSU.