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

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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.