PROJECT “Mechanisms of stability loss in high-speed foil bearings – modeling and experimental validation of thermomechanical couplings” 2018-2022.
No. 2017/27/B/ST8/01822 financed by the National Science Center, Poland.
RESEARCH TEAM:
AGH University of Science and Technology, Faculty of Mechanical Engineering and Robotics, Department of Robotics and Mechatronics, al. A. Mickiewicza 30, 30-059 Krakow, Poland:
Adam Martowicz, PhD, DSc
Jakub Roemer, PhD
Paweł Zdziebko, PhD
Jakub Bryła, PhD student
Sławomir Kantor, PhD student
Jan Pawlik, PhD student
Institute of Fluid Flow Machinery, Polish Academy of Sciences, Department of Turbine Dynamics and Diagnostics, ul. Fiszera 14, 80-231 Gdańsk, Poland:
Grzegorz Zywica, PhD, DSc
Pawel Baginski, PhD
CONTACT:
adam.martowicz@agh.edu.pl
Significance of the undertaken research
The growing consumer demands and global competition require machine and device manufacturers to continuously improve their products. As a consequence, their attention is focused on improving the quality, operational parameters and reliability of the manufactured goods, as well as on reducing energy consumption and miniaturization of the technical solutions, newly introduced to the market. In order to achieve higher power and efficiency of the manufactured devices exhibiting smaller dimensions, it is necessary to use ever higher speeds of working elements. This also applies to various types of turbomachines with the rotors reaching higher and higher rotational speeds. As a result, there is an increase in demand for new, unconventional methods of bearing the high-speed machines. The project proposed a new method for testing radial gas foil bearings.
The conducted research follows the currently observed trend of developing highly efficient and environmentally friendly technical solutions. As part of the project, new knowledge was gained in the scope of interactions between the thermal and mechanical parameters for all the phases of bearing’s operation and on their dynamic properties, including the case of use of the selected types of smart materials. Moreover, the new results were presented regarding the possibility of geometry improvement for the structural part of the suspension layer and there was proposed the innovative construction of specialized top foils performing measurement and control tasks. As a consequence, it is expected that the knowledge gained during the project will allow for the development of more effective technical solutions, e.g., microturbines and other various types of drives and generators. The investigators presented the possibilities of improving and controlling the properties of the tested type of bearings and indicated potential directions for the development of new technologies with the use of innovative design solutions, new materials as well as control and measurement components.
Overview on the project's outcomes
Despite the significant advantages of gas foil bearings, it is difficult to maintain the conditions of their stable operation, i.e., to maintain a gas film of an appropriate thickness. These conditions depend, among other factors, on the temperature distribution in the foils. An unfavorable spatial temperature distribution may result in damage of a bearing node, which, in the case of gas foil bearings, has a rapid course and lacks of earlier symptoms. In reference to the existing deficiency of knowledge regarding the comprehensive understanding of the behavior of gas foil bearings, especially during the formation and loss of the air film, the project’s investigators undertook the task of identifying the phenomena accompanying the subsequent phases of the operation of the above-mentioned bearings, i.e., during run-up, stable operation and run-out. In order to obtain new results of the experimental research, not yet reported in the literature, a unique measurement technique was proposed and successfully verified in laboratory conditions as part of the project, enabling identification of the temperature and strain fields in a top foil. The knowledge on the thermal and mechanical properties of the foil enabled the characterization of the lubricating film, and thus the assessment of the possibility of maintaining stable operation of the bearing. Simultaneous measurement of temperature and strain was feasible thanks to the innovative approach that integrated thermocouple sensors and strain gauges with a top foil.