The Experts below are selected from a list of 39 Experts worldwide ranked by ideXlab platform

Matteo Nuti - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic Identification of 280mm Diameter Tilting Pad Journal Bearings: Test Results and Measurement Uncertainties Assessment of Different Designs
    Volume 10A: Structures and Dynamics, 2020
    Co-Authors: Riccardo Ferraro, Alice Innocenti, Mirko Libraschi, Michele Barsanti, Enrico Ciulli, Paola Forte, Matteo Nuti
    Abstract:

    Abstract Tilting pad journal bearings (TPJBs) are crucial elements in turbomachinery applications providing stiffness and damping characteristics that determine rotor system dynamic behavior. Hence, a correct design and an accurate dynamic properties prediction is fundamental for the successful industrial operation of rotating machinery. Current design trends in turbomachinery aiming at Higher efficiency and power through weight optimization and Higher operating Speeds determine the development of large flexible rotors that are particularly important from the rotordynamic standpoint. The dynamic feasibility of this type of machine relies on bearing stiffness and damping characteristics that must be predicted with a certain level of confidence in order to increase the accuracy of the expected rotordynamic behaviour and avoid unpredicted vibration issues when rotors are operated. Furthermore, large centrifugal compressors commonly used in Liquified Natural Gas (LNG) applications make the bearings operate at very High Peripheral Speed where the transition from laminar to turbulent regime occurs, increasing the necessity of predictions accuracy. In this paper a test campaign on different large TPJB solutions operating in turbulent lubrication regime has been performed on a dedicated test rig designed for investigations on large size High-performance oil bearings. In the present work both static performance and dynamic identification of the tested TPJB solutions are presented and compared to numerical model predictions. The results of an uncertainty quantification, performed to validate the experimental results, are also shown.

Baldassarre Leonardo - One of the best experts on this subject based on the ideXlab platform.

  • An Efficient Iterative Coupled Model for the Study of the Insurgence of the Morton Effect in Tilting Pad Journal Bearings
    'ASME International', 2019
    Co-Authors: Griffini Duccio, Salvadori Simone, Meli Enrico, Panconi Simone, Ridolfi Alessandro, Rindi Andrea, Martelli Francesco, Panara Daniele, Baldassarre Leonardo
    Abstract:

    The introduction of the tilting pad journal bearing (TPJB) technology has allowed the achievement of important goals regarding turbomachinery efficiency in terms of High Peripheral Speed, enhanced power density, Higher efficiency, and tolerated loads. That kind of technology overcomes the typical dynamic instability problem that affects fixed geometry bearings but, under certain working conditions, can be subjected to thermal instability phenomena, which are particularly significant at High Peripheral Speeds. In this work, the authors propose an innovative iterative procedure to forecast the thermal instability onset by using two coupled models, a thermo-structural one and a fluid dynamic one. The first one calculates the vibrations and the deformations due both to the external forces and to the temperature distribution applied on the rotor. The fluid dynamic model calculates the temperature profile by using as inputs the characteristics of the rotor, of the bearing and of the orbits, obtained by the thermos-structural code. After a general description of the iterative procedure is given, details of each tool are provided. Code validation is presented by means of comparison with available experimental and numerical data. Finally, the results of the iterative procedure are shown to prove its potential in forecasting instability thresholds. The model has shown a good trade-off between accuracy and efficiency, which is very critical when dealing with the extended time windows characterizing thermal instabilities. This research activity is in cooperation with the industrial partner Baker Hughes, a GE company, which provided the experimental data obtained thorough a dedicated experimental campaign

Hitoshi Hata - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of Property Difference between Traction Oil and Traction Grease
    Journal of Advanced Mechanical Design Systems and Manufacturing, 2009
    Co-Authors: Masashi Yamanaka, Kouji Kumagai, Katsumi Inoue, Hitoshi Hata
    Abstract:

    In this paper, the characteristics of traction grease are evaluated. The difference in film formation ability between traction oil and traction grease is focused on, and the state of film formation and the traction coefficient of traction oil and two types of traction grease with different consistencies are measured simultaneously while varying temperature, Hertzian pressure and rolling Speed. The traction coefficient of traction grease at a low temperature, a low pressure and a High Peripheral Speed shows a value larger than that of traction oil. The film thickness of traction grease is measured by the contact ratio method and decreases markedly at a low temperature and a High Peripheral Speed compared with that of traction oil. An estimation formula for traction grease considering film thickness is developed. These results lead to the conclusion that the property change between traction oil and traction grease is caused by the change of the film formation state.

Riccardo Ferraro - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic Identification of 280mm Diameter Tilting Pad Journal Bearings: Test Results and Measurement Uncertainties Assessment of Different Designs
    Volume 10A: Structures and Dynamics, 2020
    Co-Authors: Riccardo Ferraro, Alice Innocenti, Mirko Libraschi, Michele Barsanti, Enrico Ciulli, Paola Forte, Matteo Nuti
    Abstract:

    Abstract Tilting pad journal bearings (TPJBs) are crucial elements in turbomachinery applications providing stiffness and damping characteristics that determine rotor system dynamic behavior. Hence, a correct design and an accurate dynamic properties prediction is fundamental for the successful industrial operation of rotating machinery. Current design trends in turbomachinery aiming at Higher efficiency and power through weight optimization and Higher operating Speeds determine the development of large flexible rotors that are particularly important from the rotordynamic standpoint. The dynamic feasibility of this type of machine relies on bearing stiffness and damping characteristics that must be predicted with a certain level of confidence in order to increase the accuracy of the expected rotordynamic behaviour and avoid unpredicted vibration issues when rotors are operated. Furthermore, large centrifugal compressors commonly used in Liquified Natural Gas (LNG) applications make the bearings operate at very High Peripheral Speed where the transition from laminar to turbulent regime occurs, increasing the necessity of predictions accuracy. In this paper a test campaign on different large TPJB solutions operating in turbulent lubrication regime has been performed on a dedicated test rig designed for investigations on large size High-performance oil bearings. In the present work both static performance and dynamic identification of the tested TPJB solutions are presented and compared to numerical model predictions. The results of an uncertainty quantification, performed to validate the experimental results, are also shown.

Griffini Duccio - One of the best experts on this subject based on the ideXlab platform.

  • An Efficient Iterative Coupled Model for the Study of the Insurgence of the Morton Effect in Tilting Pad Journal Bearings
    'ASME International', 2019
    Co-Authors: Griffini Duccio, Salvadori Simone, Meli Enrico, Panconi Simone, Ridolfi Alessandro, Rindi Andrea, Martelli Francesco, Panara Daniele, Baldassarre Leonardo
    Abstract:

    The introduction of the tilting pad journal bearing (TPJB) technology has allowed the achievement of important goals regarding turbomachinery efficiency in terms of High Peripheral Speed, enhanced power density, Higher efficiency, and tolerated loads. That kind of technology overcomes the typical dynamic instability problem that affects fixed geometry bearings but, under certain working conditions, can be subjected to thermal instability phenomena, which are particularly significant at High Peripheral Speeds. In this work, the authors propose an innovative iterative procedure to forecast the thermal instability onset by using two coupled models, a thermo-structural one and a fluid dynamic one. The first one calculates the vibrations and the deformations due both to the external forces and to the temperature distribution applied on the rotor. The fluid dynamic model calculates the temperature profile by using as inputs the characteristics of the rotor, of the bearing and of the orbits, obtained by the thermos-structural code. After a general description of the iterative procedure is given, details of each tool are provided. Code validation is presented by means of comparison with available experimental and numerical data. Finally, the results of the iterative procedure are shown to prove its potential in forecasting instability thresholds. The model has shown a good trade-off between accuracy and efficiency, which is very critical when dealing with the extended time windows characterizing thermal instabilities. This research activity is in cooperation with the industrial partner Baker Hughes, a GE company, which provided the experimental data obtained thorough a dedicated experimental campaign