Experimental Investigation of the Unsteady, Three-dimensional Fluid Cavitation in Lubricant Flow

• Applicant: Professor Dr.-Ing. Peter Reinke
• Subject Area: Fluid Mechanics ; Hydraulic and Turbo Engines and Piston Engines
• Term: from 2021 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 462581008

• Final Report Year: 2023

Final Report Abstract

This report presents current research comparing gaseous and vaporous cavitation in lubricant flows obtained by means of digital high-speed photography in un-precedented detail. Hydrodynamic journal bearings are compact and guarantee a nearly wear-resistant operation. These features make journal bearings the first choice for many applications. However, under particular operational conditions, e.g. a highly dynamic load, cavitation can occur which can lead to bearing failures. For the selected case of suction cavitation these conditions are characterized by high eccentricity combined with a rapid variation of the lubricating film thickness. The work at hand presents a new experimental approach to study suction cavitation in a scaled bearing model. Moreover, mechanical and fluid dynamic similarity laws are described which enable the transfer of bearing operation conditions into the model experiment and vice versa. An extensive literature research yields the parameters of operating conditions that are critical towards suction cavitation and puts the definition of cavitation into the particular perspective of the lubricating flow in journal bearings. The new experimental approach includes a specially designed fluid, which fulfills Reynolds and cavitation similarity and a scaled bearing model including a mechanism that re-produces the specific phases of shaft displacement which are necessary for the inception of cavitation. The experimental results include high-speed photography that captures the formation of bubbles at a rate of 10.000 frames per second (fps) which enables a detailed analysis of bubble growth yielding precise input data for an evaluation and comparison with simulation results. Numerical simulations are carried out by means of an unsteady and three-dimensional model utilizing a 2-phase code that is state-of-the-art for the bearing design process. In summary, the work at hand provides a deeper understanding of the process of suction cavitation in dynamically loaded journal bearings. The applicant succeeded in transferring the results obtained during this project and experiences with the numerical model on other applications such as squeeze film dampers. The squeeze film damper is a core component when is comes to controlling the vibrations of jet engines in aeronautical applications.

Publications

• Experimentelle Untersuchung der instationären, dreidimensionalen Flüssigkeitskavitation in der Schmierspaltströmung. 28. Fachtg. Exp. Strömungsmechanik, 25-1 – 25-8. ISBN: 978-3-9816764-7-1, 2021.
  T. Beckmann; M. Schmidt; J. Ahlrichs & P. Reinke
  
• Analyse von Hochgeschwindigkeitsaufnahmen der Flüssigkeitskavitation in der exzentrischen Schmierspaltströmung. 29. Fachtg. Exp. Strömungsmechanik, 46-1 – 46-8. ISBN: 978-3-9816764-8-8, 2022.
  T. Beckmann; M. Schmidt; J. Ahlrichs & P. Reinke
  
• High-Speed Digital Photography of Gaseous Cavitation in a Narrow Gap Flow. Fluids, 7(5), 159.
  Reinke, Peter; Ahlrichs, Jan; Beckmann, Tom & Schmidt, Marcus
  
• Analyse der Blasendynamik der Flüssigkeitskavitation im Schmierfilm eines hydrodynamischen Gleitlagers. 30. Fachtagung Experimentelle Strömungsmechanik, 10-1 – 10-8. ISBN: 978-3-9816764-9-5, 2023.
  T. Beckmann; M. Schmidt; J. Ahlrichs & P. Reinke
  
• Dampfkavitation in der Schmierspaltströmung. Vortrag FEM-Kolloquium, Universität Erlangen, 02. März 2023.
  M. Schmidt
  
• Digital High-Speed Photography of Cavitation in Journal Bearings. SAE Technical Paper Series, 1. Society of Automotive Engineers of Japan.
  Reinke, Peter; Rienaecker, Adrian; Schmidt, Marcus & Beckmann, Tom
  
• High-Speed Digital Photography of Vapor Cavitation in a Narrow Gap Flow. Fluids, 8(2), 44.
  Reinke, Peter; Beckmann, Tom; Ahlers, Caroline; Ahlrichs, Jan; Hammou, Lamyaa & Schmidt, Marcus
  
• High-speed Photography of Cavitation in Oil-filled Narrow Gaps. Eingeladener Vortrag, Seminar Nichtlineare Dynamik, Institut für Physik, Lehrstuhl Soft Matter, 20. Juni 2023 in Magdeburg.
  P. Reinke & M. Schmidt
  
• Hochgeschwindigkeitsaufnahmen von Kavitation im Schmierfilm. Eingeladener Vortrag, Ehemaligentreffen der Mechanik, Leibniz Universität Hannover, 16. Juni 2023 in Garbsen.
  P. Reinke; M. Schmidt; T. Beckmann; J. Ahlrichs & A. Rienäcker
  
• Hochgeschwindigkeitsaufnahmen von Kavitation in ölgefüllten engen Spalten. Eingeladener Vortrag, Session: Kavitation mit Schwerpunkt maritimer Kontext 2, Nr. DAGA2023/554. Jahrestagung für Akustik, DAGA 2023, 06.-09. März 2023 in Hamburg.
  P. Reinke; M. Schmidt; T. Beckmann; J. Ahlrichs & A. Rienäcker