Clearance Regulation of Mechanical Gas Face Seals: Part II- Analysis and Controls


This article presents the analysis and control of noncontacting mechanical gas face seals based on the state space model developed in Part I. Methods to analyze the controllability and observability of axial and tilt modes are described. The controllability analysis determines. To what extent the dynamic response of the seal system modes can be shaped in a closed-loop feedback system, and the observability analysis determines if the seal system modes can be reconstructed from specific state measurements of the axial clearance and stator tilts. The error state-space method is employed to design a tracking controller to regulate the seal at a prescribed axial clearance. The control law is a function of all axial states; therefore, reduced order linear observers are designed to observe the unmeasured axial and tilt seal states. The axial clearance and tilt state estimates are used to reconstruct the gas film axial force and moments, which cannot be directly measured, for design and analysis. The analysis and control techniques are applied to the illustrative example presented in Part I. The results demonstrate that the gas film forces and moments can be estimated well and the seal system can be satisfactorily regulated with a sufficiently damped response that is within the bandwidth of today's electropneumatic actuators.


Mechanical and Aerospace Engineering

Keywords and Phrases

Feedback; Feedback Regulation; Tilt Angle; Actuators; Axial loads; Measurement; Modeling

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Document Type

Article - Journal

Document Version


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© 2006 Taylor & Francis Group, All rights reserved.

Publication Date

01 Jan 2006