Development of a methodology for the simulation of oil splash in conventional and electrical powertrains using particle-based methods

In recent decades, computational simulations have played a key role in engineering. Designers and companies increasingly require software with greater precision and accuracy, able to deal with an ever-increasing spectrum of physical phenomena. This has prompted programmers not only to improve and update the already pre-existing ones but to develop new approaches and methodologies, capable of overcoming the limitations of previous technologies. In this context, SPH represents a completely alternative method to those commonly used until now, like CFD, because of its Lagrangian approach and meshless features. In particular, the most interesting aspect concerns its ability to reproduce free surface monophase and multiphase flows and high-speed dynamics. The software used for these particles-based simulations is “PreonLab”, developed by “Fifty2 Technology GmbH”. The work has been mainly divided into two parts. Since no such software had ever been used inside the company, a first part of calibration and validation was opted for. Thanks to photographic and video analyses carried out on a test bench to evaluate the piston jet cooling in a gasoline turbocharged engine, an attempt was made to replicate the fluid's behaviour under these conditions and to acquire adequate know-how. Several simulations were run, trying to achieve a good correlation between measured and simulated data. The analysis is mainly divided into two subsections: a qualitative and a quantitative one. The first concerns a visual comparison with the experimental videos and images to assess the oil behaviour at different pressures and temperatures. The second one is focused on a thermal analysis to evaluate the heat transfer between the oil and the piston, by simulating the heating-up phase of two different pistons with an oil jet. Once this validation and calibration phase was over and the main features of the software were understood, the second part of the thesis, focused on the evaluation and optimization of the lubrication inside a gearbox started. Due to the complexity of the geometries, these types of simulations were a demanding challenge for common simulation software, making mesh design problematic, but this approach can greatly simplify the model. Different design variants and boundary conditions were simulated to optimise the lubrication under all operating conditions. The simulation results were already employed to improve the design of the machine.