Study of optimal performance characteristics for high speed and high load offset pressure dam bearing considering thermal and turbulent effects

Abstract

newline Application of hydrodynamic journal bearings such as pressure dam and offset in high-speed and high-power turbo machines face immense challenges to deliver optimum static and dynamic performances under various operating conditions. Stability, efficiency and oil flow are Critical to Quality (CTQ) requirements for these machines and hence the optimum design of journal bearings is required to meet all the performance requirements. For example, bearings designed for optimum static performance at full load and full speed conditions, could not deliver stable dynamic performance at no-load conditions. In this study, offset and pressure dam geometries are combined into the same bearing and analyzed if the combination can deliver the optimum performance characteristics. The governing mathematical models of Reynold s equation and energy equation include turbulent and adiabatic thermal effects. The selection of the bearing type and design would make a large difference in the performance of these machines. In summary, newline1. Offset bearing can deliver acceptable dynamic characteristics at all operating conditions with a compromise on static performance. newline2. While pressure dam bearings are good at static performance, they do not meet dynamic requirements at high-speed no-load conditions. They are most suitable for lower journal velocities. newline3. The combined offset pressure dam bearing produces optimum static and dynamic performance between pressure dam and offset bearings at all operating conditions. newline4. The combined offset pressure dam bearing consumes lesser oil flow and power loss than offset bearing and delivers stable operation at all operating conditions. newline5. Also, combined offset pressure dam bearing provides stable performance of the rotor at system level study. Hence, it can be considered as one of the optimum bearing designs for high-speed, high-load turbo machinery applications. newline6. As it is very challenging for the bearing designers to choose the best bearing type for these applications, this research will al