Numerical modeling of the power losses in geared transmissions: Windage, churning and cavitation simulations with a new integrated approach that drastically reduces the computational effort

Self Cite

Many researches were conducted in the past in order to maximise the efficiency of gearboxes, and for many of the sources of power loss, very effective models and tools are already available and can significantly help to optimise the design. Nevertheless, for the load‐independent power losses of gears only in the recent years some progress has been made. Concerning these losses, numerical simulations can help the designers in optimising the internal shape of the casing, thus ensuring the proper lubrication of all the components and reducing the undesired splashing losses. The amount of lubricant plays a fundamental role: A reduction of the lubricant can be critical from the point of view of adequate lubrication and of failures of the system due to wear, scuffing, and pitting but, on the other side, an excessive amount of lubricant leads to additional power dissipation and could even determine an overheating of the system. Another possibility to improve efficiency could be represented by the reduction of the pressure inside the housing: in this paper, the effect of the static pressure on the load‐independent power losses both for complete‐ and dip‐lubrication has been deeply studied. The numerical results, validated by experimental data, show that a reduction up to 15% of the churning losses can be achieved without reducing the amount of lubricant, that is, without increasing the risk of failures related to lubrication. Based on the results obtained, the reduction of the pressure of the housing proves to be a way to improve the efficiency, provided the related engineering issues are also addressed.

Section: Modelling Approachmentioning

confidence: 87%

“…In Concli and Gorla, the techniques used to adapt the model to both conditions of complete‐ and dip‐lubrication are also described.…”

Section: Modelling Approachmentioning

confidence: 99%

See 1 more Smart Citation

Effect of the static pressure on the power dissipation of gearboxes

Concli

Gorla

Rosa

et al. 2019

Self Cite

“…The solution of the system of equation is performed with numerical techniques based on a PIMPLE (merged PISO‐SIMPLE) algorithm …”

Section: Introductionmentioning

confidence: 99%

“…While the fluid dynamic solver was already available, the algorithm for the boundary motion, the automatization of the mesh generation and update, as well as the assembly of the different partitions was newly developed. As accurately described in Concli and Gorla, before each time step, all the dictionaries that control the simulation were automatically modified. The fluid dynamic is solved upon a prescribed time for which the mesh reaches the maximum acceptable distortion.…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of the churning power losses in planetary gearboxes: An innovative partitioning‐based meshing methodology for the application of a computational effort reduction strategy to complex gearbox configurations

Concli

Gorla

2017

Self Cite

Thanks to the recent developments in the computer science, simulations are becoming an increasingly widespread approach that can help the designers in the development of new products. In the specific field of gearboxes, simulations are used mainly for structural evaluations. However, while for the structural design beside the simulations, many analytical methods and international standard are available; for the prediction of the power losses and the efficiency of gears, neither accurate analytical methods nor automated simulation tools are available. The authors work on this topic since years and have developed new methodologies based on computational fluid dynamics. With respect to general purpose commercial software, these techniques allow a significant reduction of the computational effort and have the capability to take into account particular physical phenomena that occurs in gears, such as cavitation, and for which no information are available in literature. The purpose of this paper is to introduce a new automated mesh‐partitioning strategy implemented to extend the applicability of the previously developed computational effort reduction method to complex gearboxes getting over the geometrical limitations adopted in the past. To show the capabilities of this new strategy, we simulated a planetary gearbox that represents at the same time one of the most complicated kinematic arrangements of gears and the configuration for which the numerical fluid dynamics simulation can give the major contribution both with planar simplified models as well as with complete 3D models.

Research on characteristics of splash lubrication and power losses of reducer based on MPS method

Liu

Tao

Zhou

et al. 2023

The distribution of lubricant flow field inside the two‐stage transmission reducer is very complicated during splash lubrication, which is difficult to be visually simulated and analysed using traditional finite element methods (FEM). There are many problems in model processing, algorithm selection, mesh division, and computational workload. Through sufficient investigation and experimental validation based on literature, the moving particle semi‐implicit (MPS) method is proposed to study the splash lubrication characteristics of a rail vehicle reducer. Through this method, the visual simulation calculation of multiple working conditions of reducer with complex structure is realised, and the unreasonable structure of the gearbox body is optimised. The model of oil supply demand in the Hertz contact zone of gear transmission is established, and the time‐domain variation law of oil particles number in the contact zone and oil supply state are analysed. It is found that the optimised reducer model can meet the demand of oil supply under the four typical working conditions of the rail vehicle. The higher the initial oil volume is, the more sufficient the oil supply is. Compared with the working temperature conditions of 20 and 80 °C, the lubrication effect is better at 40 and 60 °C. By analysing the power loss proportion of each gear, it is found that the sum of power loss of gear 1 and gear 2 is dominant under different working conditions, reaching 76%–99.5% of the total churning power losses.