CFD Evaluation and Optimization of Oil Tank Fluid Dynamics For Turbomachinery Lubrication System

The modern turbo-machinery market sets constantly new challenges for manufacturers to be competitive, pushing the need to introduce new technological solutions or optimize the existing ones at their maximum level. Each sub-system that sustains the turbomachinery train operation, such as the Lube Oil system, has its own peculiarities and constraints. In particular, the industrial market requires a strong reduction of cost and lead time, maintaining the same main functionalities and possibly simplifying the configuration layout and the maintenance procedure. When designing a Lube Oil Console, one of the main requirements is given in the form of minimum retention time, which is normally estimated simply by dividing the tank volume by the design flow rate. This parameter should synthetically ensure a proper degassing effectiveness of the system, in order to avoid cavitation issues on the oil pumps. However, a more detailed study on this topic is beneficial to understand the real behavior of the oil flow inside the Lube Oil tank and to assess its capability to remove air bubbles within the entire volume. For this reason, a dedicated series of CFD analyses was performed to study the flow structure, to estimate the real retention time and the related degassing effectiveness. In order to save time and cost, a simplified numerical approach was used, developing a fast method to perform the assessment in all projects. This approach required a fine-tuning of the computational parameters, comparing the results with available experimental data that were used for the validation of the methodology. The analysis results showed that the real traveling time of the oil is lower than the theoretical retention time, but the related degassing capability is sufficient, leaving space for potential future alternative conceptual configurations.