Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators
Based on experimental pieces of evidence collected in a set of twenty healthy large hydrogenerators, this article shows that the operating conditions of the tilting pad journal bearings of these machines may have unpredictable and significant changes. This behavior prevents the theoretical determina...
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| Format: | Article |
| Language: | English |
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Wiley
2017-01-01
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| Series: | Shock and Vibration |
| Online Access: | http://dx.doi.org/10.1155/2017/4647868 |
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| _version_ | 1849408460810092544 |
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| author | Geraldo Carvalho Brito Roberto Dalledone Machado Anselmo Chaves Neto |
| author_facet | Geraldo Carvalho Brito Roberto Dalledone Machado Anselmo Chaves Neto |
| author_sort | Geraldo Carvalho Brito |
| collection | DOAJ |
| description | Based on experimental pieces of evidence collected in a set of twenty healthy large hydrogenerators, this article shows that the operating conditions of the tilting pad journal bearings of these machines may have unpredictable and significant changes. This behavior prevents the theoretical determination of bearing stiffness and damping coefficients with an adequate accuracy and makes damage detection difficult. Considering that dynamic coefficients have similar sensitivity to damage and considering that it is easier to monitor bearing stiffness than bearing damping, this article discusses a method to estimate experimentally the effective stiffness coefficients of hydrogenerators journal bearings, using only the usually monitored vibrations, with damage detection purposes. Validated using vibration signals synthesized by a simplified mathematical model that simulates the dynamic behavior of large hydrogenerators, the method was applied to a journal bearing of a 700 MW hydrogenerator, using two different excitations, the generator rotor unbalance and the vortices formed in the turbine rotor when this machine operates at partial loads. The experimental bearing stiffnesses obtained using both excitations were similar, but they were also much lower than the theoretical predictions. The article briefly discusses the causes of these discrepancies, the method’s uncertainties, and the possible improvements in its application. |
| format | Article |
| id | doaj-art-79da8cd65d274cf1ae5e29434348c4f2 |
| institution | Kabale University |
| issn | 1070-9622 1875-9203 |
| language | English |
| publishDate | 2017-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Shock and Vibration |
| spelling | doaj-art-79da8cd65d274cf1ae5e29434348c4f22025-08-20T03:35:47ZengWileyShock and Vibration1070-96221875-92032017-01-01201710.1155/2017/46478684647868Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large HydrogeneratorsGeraldo Carvalho Brito0Roberto Dalledone Machado1Anselmo Chaves Neto2Center for Engineering and Exact Sciences, Western Paraná State University (UNIOESTE), Foz do Iguaçu, PR, BrazilNumerical Methods for Engineering Graduate Program, Federal University of Paraná (UFPR), Curitiba, PR, BrazilNumerical Methods for Engineering Graduate Program, Federal University of Paraná (UFPR), Curitiba, PR, BrazilBased on experimental pieces of evidence collected in a set of twenty healthy large hydrogenerators, this article shows that the operating conditions of the tilting pad journal bearings of these machines may have unpredictable and significant changes. This behavior prevents the theoretical determination of bearing stiffness and damping coefficients with an adequate accuracy and makes damage detection difficult. Considering that dynamic coefficients have similar sensitivity to damage and considering that it is easier to monitor bearing stiffness than bearing damping, this article discusses a method to estimate experimentally the effective stiffness coefficients of hydrogenerators journal bearings, using only the usually monitored vibrations, with damage detection purposes. Validated using vibration signals synthesized by a simplified mathematical model that simulates the dynamic behavior of large hydrogenerators, the method was applied to a journal bearing of a 700 MW hydrogenerator, using two different excitations, the generator rotor unbalance and the vortices formed in the turbine rotor when this machine operates at partial loads. The experimental bearing stiffnesses obtained using both excitations were similar, but they were also much lower than the theoretical predictions. The article briefly discusses the causes of these discrepancies, the method’s uncertainties, and the possible improvements in its application.http://dx.doi.org/10.1155/2017/4647868 |
| spellingShingle | Geraldo Carvalho Brito Roberto Dalledone Machado Anselmo Chaves Neto Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators Shock and Vibration |
| title | Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators |
| title_full | Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators |
| title_fullStr | Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators |
| title_full_unstemmed | Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators |
| title_short | Experimental Estimation of Journal Bearing Stiffness for Damage Detection in Large Hydrogenerators |
| title_sort | experimental estimation of journal bearing stiffness for damage detection in large hydrogenerators |
| url | http://dx.doi.org/10.1155/2017/4647868 |
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