Effects of fluid inertia and cavitation on the force coefficients of a squeeze film damper /
| Main Author: | |
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| Other Authors: | , , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
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| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | Squeeze film dampers are used to provide the required damping to high speed rotating machinery with rolling-element bearings. Accurate evaluation of the damper performance requires accurate prediction of the pressure distribution around the journal for a given motion. However, the pressure distribution is affected by many factors; geometry of the squeeze film region, fluid inertia, cavitations, etc. The short open ended squeeze film damper executing circular centered orbits is studied here. A modified Reynolds equation is used to find the effects of finite length and fluid inertia on the force coefficients of the damper. The viscous solution is found first by a regular perturbation including a finite length correction factor. The correction factor employed here is an improvement over previous work, as it avoids singularity for large orbit radius and increases the accuracy of predicted force coefficients. Considering the effects of fluid inertia, the analysis shows that both the damping and inertia force coefficients increase as the squeeze film Reynolds number increases. The effect of vapor cavitation on the pressure distribution and the force coefficients of a long squeeze film damper executing circular centered orbits is also studied in association with the Swift-Stieber cavitation boundary conditions. The existence of vapor cavitation significantly decreases the whole of the pressure distribution. A modified Reynolds equation is solved analytically for a long squeeze film damper to investigate the effect of fluid inertia on cavitated pressure profiles. Increasing fluid inertia tends to extend the region of cavitation to the minimum film gap and to reduce the pressure. The corresponding damping and inertia force coefficients are presented for varying positions of cavitation inception and termination. A solution of the cavitated long squeeze film damper is modified considering side leakage of end seals. The Swift-Stieber conditions and leakage factor used can improve the prediction of cavitation effects and end leakage effects on the performance of a squeeze film damper. Experimental tests were performed on a squeeze film damper test rig to measure the dynamic pressure distribution and force coefficients with large orbit radius equal to 0.8. The L/D ratio is 0.188. Two types of configurations are tested; fully open ended and partially sealed configurations. In the past, most measurements of a squeeze film damper have been carried out at Reynolds number not exceeding 10, but in practical applications the squeeze film damper Reynolds number actually ranges from 10 to 50. The measurements in this study completely cover the practical range of Reynolds number. The experimental results reported here show the significance of fluid inertia and cavitation in the analysis of the damper performance. |
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| Item Description: | Typescript (photocopy). Vita. "Major subject: Mechanical engineering." |
| Physical Description: | xviii, 178 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |