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Imbalance response of a rigid rotor supported on end sealed integral squeeze film dampers
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Modern turbomachinery design directs towards the ographics. generation or utilization of increasing amounts of power with the minimum engine weight. High performance turbomachinery requires of appropriate means to ensure structural isolation of components and rotor vibration limits with tolerance to sudden imbalance loads due to blade loss events, shock, and maneuver actions. Squeeze film dampers (SFDS) are an effective mean to reduce vibrations and to suppress instabilities in high performance aeroengine systems. The recently developed integral squeeze film dampers (ISFDS) offer several advantages over conventional SFDS such as reduced overall weight and length of the damper structure with less number of parts, accuracy of positioning (centering), and a split segment construction allowing easier assembly, inspection, and retrofit than with any other type of damper. The objective of the experimental program is the identification of the damping coefficients of sealed ISFDS from measurements of the imbalance response of a massive rotor supported on two (identical) integral dampers. Experiments are conducted on dampers with end plate seals of known clearance. The amplitudes of synchronous rotor response at the first critical speed, for increasing levels of imbalance, allow the determination of system amplification factors and the Measurements of oil flow rates, impact tests and imbalance response tests demonstrate that end gap seals render a substantial increase in the ISFD viscous damping coefficients and with only a small reduction on the flow through the dampers. The sealed integral dampers genemte viscous damping coefficients larger than two times the test values obtained earlier for open ended dampers. Conventional (cylindrical) sealed SFDS restrict substantially the lubricant through flow and determine minimal increments in the damping coefficients because the lubricant viscosity decreases as the operating film temperature raises. The experiments further demonstrate that the amplitudes of rotor synchronous response at the first and second critical speeds are proportional to the imbalance displacements. No subsynchronous frequencies or (nonlinear) jump phenomenon are ever observed in any of the tests. FEM predictions of the viscous damping coefficients for the end sealed ISFDS agree favorably with the identified damping coefficients when accounting for the effect of air entrainment in the squeeze film. The experimental verification and theoretical validation of the damping capability of sealed ISFDS demonstrates the benefit of this novel technology of application in high performance turbomachinery.
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Includes bibliographical references (leaves 57-59).
De Santiago Duran, Oscar Cesar (1998). Imbalance response of a rigid rotor supported on end sealed integral squeeze film dampers. Master's thesis, Texas A&M University. Available electronically from
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