CFD-simulation of no-load power losses and the oil distribution of spur gears
Final Report Abstract
The performed investigations show the complexity of the gearbox fluid flow and no-load loss torque emergence. By means of CFD, a detailed analysis of the interaction between gears and oil in a gearbox is possible. A suitable simulation methodology is required with focus on the CFD model and setup. Within the FVM, a discretization with element lengths of 1 mm enables a precise calculation of characteristic structures within the gearbox oil flow. The sliding mesh method allows to model the rotation of single disks and gears. The remeshing method is able to consider the gear mesh and is suitable to calculate gear pairs. The remeshing method shows higher calculation effort compared to the sliding mesh method. The compressive VoF approach is suitable for multiphase gearbox oil flow simulations. An acceleration ramp provides numerical stability and aids the quick formation of a resilient quasi-stationary simulation state. Hereby the acceleration value in the magnitude of a = 40 m/s² was tested successfully. The SPH-based simulations showed strong fluctuations with amplitudes on the order of the target values at high rotational velocities. During the project the focus was directed towards the development of a simple, but robust and accurate SPH model for quantitative predictions of churning gear power losses. Artificial numerical stabilization techniques like density-diffusion terms, artificial viscosity or the usage of more dissipative Riemann solver were omitted on purpose. Nonetheless, a new multiphase formulation was developed and implemented in a new optimized GPU-based simulation framework. This model allowed for stable simulations of gear-lubricant interactions at moderate rotational speeds and showed much improved capabilities for high rotational speeds. Additionally, the performance gain of the raw simulations enables much longer physical simulation times to level out the highly transient initial ramp-up phase. Together with latest hardware this approach shows very promising results for the prediction of churning losses at circumferential speeds above 10 m/s, i.e. 1736 rotations per minute for the investigated geometry. To the best knowledge of the authors, no other comparably simple SPH method is available in literature that reaches stable multiphase interface simulations for such violent configurations. Therefore, we continue exploring the achievements in terms of quantitative comparisons for the churning losses and more general multiphase simulation capabilities.
Publications
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Determination of oil distribution and churning power loss of gearboxes by finite volume CFD method. Tribology International, 109, 346-354.
Liu, Hua; Jurkschat, Thomas; Lohner, Thomas & Stahl, Karsten
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Detailed Investigations on the Oil Flow in Dip-Lubricated Gearboxes by the Finite Volume CFD Method. Lubricants, 6(2), 47.
Liu, Hua; Jurkschat, Thomas; Lohner, Thomas & Stahl, Karsten
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Efficient CFD Simulation Model for a Planetary Gearbox. Forschung im Ingenieurwesen, 82(4), 319-330.
Liu, Hua; Standl, Philipp; Sedlmair, Martin; Lohner, Thomas & Stahl, Karsten
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Numerical modelling of oil distribution and churning gear power losses of gearboxes by smoothed particle hydrodynamics. Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, 233(1), 74-86.
Liu, Hua; Arfaoui, Ghaith; Stanic, Milos; Montigny, Laurent; Jurkschat, Thomas; Lohner, Thomas & Stahl, Karsten
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Computational fluid dynamics simulation of geared transmissions with injection lubrication. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 233(21-22), 7412-7422.
Liu, H.; Link, F.; Lohner, T. & Stahl, K.
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A partitioned continuous surface stress model for multiphase smoothed particle hydrodynamics. Journal of Computational Physics, 472, 111716.
Zöller, C.; Adams, N.A. & Adami, S.
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Numerical Visualization of Grease Flow in a Gearbox. Chinese Journal of Mechanical Engineering, 36(1).
Liu, Hua; Dangl, Florian; Lohner, Thomas & Stahl, Karsten
