Analytical and experimental evaluation of the leakage and stiffness characteristics of high pressure pocket damper seals

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Title: Analytical and experimental evaluation of the leakage and stiffness characteristics of high pressure pocket damper seals
Author: Gamal Eldin, Ahmed Mohamed
Abstract: This thesis presents numerical predictions for the leakage and direct stiffness coefficients of pocket damper seals . Modifications made to earlier flow -prediction models are discussed . Leakage and static pressure measurements on straight -through and diverging configurations of eight -bladed and twelve -bladed seals were used for code validation and for calculation of seal discharge coefficients . Higher than expected leakage rates were measured in the case of the twelve -bladed seal , while the leakage rates for the eight -bladed seals were predicted reasonably accurately . Results are presented for shake tests conducted on the seals at pressures of up to 1000 Psi (6 .90 MPa ) . Test variables included pressure drop across the seals and rotor speed . The experimentally obtained stiffness coefficients are compared to results of a rotordynamic damper seal code , which uses the corrected mass flow -rate calculation method . Results show that the code under -predicts the magnitude of the seal's stiffness for most test cases . However , general trends in the frequency dependency of the direct stiffness are more accurately predicted . The expectation of high values of negative stiffness in diverging seals is confirmed by the results , but the frequency at which the sign of the stiffness becomes positive is considerably lower than is predicted . In addition to presenting high -pressure test data , this thesis also attempts to provide some insight into how seal parameters can be modified to obtain desired changes in seal stiffness .
URI: http : / /hdl .handle .net /1969 .1 /16
Date: 2004-09-30

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Analytical and experimental evaluation of the leakage and stiffness characteristics of high pressure pocket damper seals. Available electronically from http : / /hdl .handle .net /1969 .1 /16 .

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