Computer-aided engineering (CAE) refers to software applications aimed at helping solve technological problems through numerical methods. Exploiting CAE, it is possible to evaluate determined systems through virtual models rather than physical prototypes. By doing so, useful information on the system’s performance can be gathered at the beginning of the design phase, when the modifications to the project cost less. In the field of lubrication and efficiency, computational fluid dynamics (CFD) has been applied to geared transmissions, leading to an important step forward in the understanding of multiphase physics and the optimization of the systems’ layout. Being the simulations of gears non-stationary, the topological changes of the domain require the adoption of mesh-handling strategies capable of accomplishing the boundaries’ rotation. In this analysis, the Global Remeshing Algorithm with Mesh Clustering (GRAMC), previously developed by the authors to reduce the computational time associated with the remeshing process, is applied to study dip and injection lubrication in helical and spur gearboxes. The results suggest that this methodology is an effective and efficient solution to analyse the lubrication and the efficiency even for complex kinematics. The investigation was conducted in the OpenFOAM framework.
CFD, efficiency, gears, lubrication, mesh handling, OpenFOAM, power losses
 Liu, H., Jurkschat, T., Lohner, T. & Stahl, K., Determination of oil distribution and churning power loss of gearboxes by finite volume CFD method. Tribol. Int., vol. 109, pp. 346–354, 2017. https://doi.org/10.1016/j.triboint.2016.12.042
 Mastrone, M.N., Hartono, E.A., Chernoray, V. & Concli, F., Oil distribution and churning losses of gearboxes: Experimental and numerical analysis. Tribol. Int., 151, 2020. https://doi.org/10.1016/j.triboint.2020.106496
 Concli, F., Maccioni, L. & Gorla, C., Lubrication of gearboxes: CFD analysis of a cycloidal gear set. In WIT Transactions on Engineering Sciences, 123, pp. 101–112, 2019. https://doi.org/10.2495/MPF190101
 Liu, H., Jurkschat, T., Lohner, T. & Stahl, K., Detailed investigations on the oil flow in dip-lubricated gearboxes by the finite volume CFD method. Lubricants, 6(2), 2018. https://doi.org/10.3390/lubricants6020047
 Mastrone, M.N. & Concli, F., CFD simulation of grease lubrication: Analysis of the power losses and lubricant flows inside a back-to-back test rig gearbox. J. Nonnewton. Fluid Mech., 297, 2021. https://doi.org/10.1016/j.jnnfm.2021.104652
 Burberi, E., Fondelli, T., Andreini, A., Facchini, B. & Cipolla, L., CFD simulations of a meshing gear pair. In Proceedings of the ASME Turbo Expo, 5A-2016, 2016. https://doi.org/10.1115/GT2016-57454
 Hildebrand, L., Dangl, F., Sedlmair, M., Lohner, T. & Stahl, K., CFD analysis on the oil flow of a gear stage with guide plate. Eng. Res., 2021. https://doi.org/10.1007/s10010-021-00523-5
 Concli, F. & Gorla, C., A CFD analysis of the oil squeezing power losses of a gear pair. Int. J. Comput. Methods Exp. Meas., 2(2), pp. 157–167, 2014. https://doi.org/10.2495/CMEM-V2-N2-157-167
 Bianchini, C., Da Soghe, R., Errico, J.D. & Tarchi, L., Computational analysis of windage losses in an epicyclic gear train. In Proceedings of the ASME Turbo Expo, 5B-2017, 2017. https://doi.org/10.1115/GT2017-64917
 Bianchini, C., et al., Load independent losses of an aeroengine epicyclic power gear train: Numerical investigation. In Proceedings of the ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition, 2019. https://doi.org/10.1115/GT2019-91309
 Concli, F., Gorla, C., Della Torre, A. & Montenegro, G., Windage power losses of ordinary gears: different CFD approaches aimed to the reduction of the computational effort. Lubricants, 2(4), pp. 162–176, 2014. https://doi.org/10.3390/lubricants2040162
 Mastrone, M.N. & Concli, F., Power losses of spiral bevel gears: an analysis based on computational fluid dynamics. Front. Mech. Eng., 7, 2021. https://doi.org/10.3389/fmech.2021.655266
 Dai, Y., Ma, F., Zhu, X., Su, Q., & Hu, X., Evaluation and optimization of the oil jet lubrication performance for orthogonal face gear drive: Modelling, simulation and experimental validation. Energies, 12(10), 2019. https://doi.org/10.3390/en12101935
 Ferrari, C. & Marani, P., Study of air inclusion in lubrication system of CVT gearbox transmission with biphasic CFD simulation, 2016.
 Hu, X., Jiang, Y., Luo, C., Feng, L. & Dai, Y., Churning power losses of a gearbox with spiral bevel geared transmission. Tribol. Int., 129, pp. 398–406, 2019. https://doi. org/10.1016/j.triboint.2018.08.041
 Peng, Q., Zhou, C., Gui, L. & Fan, Z., Investigation of the lubrication system in a vehicle axle: Numerical model and experimental validation. Proc. Inst. Mech. Eng. Part D J. Automob. Eng., 233(5), pp. 1232–1244, 2019. https://doi.org/10.1177/0954407018766128
 Peng, Q., Gui, L. & Fan, Z., Numerical and experimental investigation of splashing oil flow in a hypoid gearbox. Eng. Appl. Comput. Fluid Mech., 12(1), pp. 324–333, 2018. https://doi.org/10.1080/19942060.2018.1432506
 Dai, Y., Jia, J., Ouyang, B. & Bian, J., Determination of an optimal oil jet nozzle layout for helical gear lubrication: Mathematical modeling, numerical simulation, and experimental validation. Complexity, 2020, 2020. https://doi.org/10.1155/2020/2187027
 Santra, T.S., Raju, K., Deshmukh, R., Gopinathan, N., Paradarami, U. & Agrawal, A., Prediction of oil flow inside tractor transmission for splash type lubrication. SAE Tech. Pap., 2019. https://doi.org/10.4271/2019-26-0082
 Lu, F., Wang, M., Bao, H., Huang, W. & Zhu, R., Churning power loss of the intermediate gearbox in a helicopter under splash lubrication. Proc. Inst. Mech. Eng. Part J J. Eng. Tribol., 2021. https://doi.org/10.1177/13506501211010030
 Deng, X., et al., Lubrication mechanism in gearbox of high-speed railway trains. J. Adv. Mech. Des. Syst. Manuf., 14(4), 2020. https://doi.org/10.1299/jamdsm.2020jamdsm0054
 Deng, X., Wang, S., Hammi, Y., Qian, L. & Liu, Y., A combined experimental and computational study of lubrication mechanism of high precision reducer adopting a worm gear drive with complicated space surface contact. Tribol. Int., 146, 2020. https://doi. org/10.1016/j.triboint.2020.106261
 Morhard, B., Schweigert, D., Mileti, M., Sedlmair, M., Lohner, T. & Stahl, K., Efficient lubrication of a high-speed electromechanical powertrain with holistic thermal management. Eng. Res., 2020. https://doi.org/10.1007/s10010-020-00423-0
 Ji, Z., Stanic, M., Hartono, E.A. & Chernoray, V., Numerical simulations of oil flow inside a gearbox by Smoothed Particle Hydrodynamics (SPH) method. Tribol. Int., 127, pp. 47–58, 2018. https://doi.org/10.1016/j.triboint.2018.05.034
 Liu, H., et al., Numerical modelling of oil distribution and churning gear power losses of gearboxes by smoothed particle hydrodynamics. Proc. Inst. Mech. Eng. Part J J. Eng. Tribol., 233(1), pp. 74–86, 2019. https://doi.org/10.1177/1350650118760626
 Legrady, B., Taesch, M., Tschirschnitz, G. & Mieth, C.F., Prediction of churning losses in an industrial gear box with spiral bevel gears using the smoothed particle hydrodynamic method. Eng. Res., 2021. https://doi.org/10.1007/s10010-021-00514-6
 Mastrone, M.N. & Concli, F., Development of a mesh clustering algorithm aimed at reducing the computational effort of gearboxes’ CFD simulations. Boundary Elements and other Mesh Reduction Methods XLIV, 131, pp. 59–69, 2021. https://doi. org/10.2495/be440051
 Mastrone, M.N. & Concli, F., CFD simulations of gearboxes: implementation of a mesh clustering algorithm for efficient simulations of complex system’s architectures. Int. J. Mech. Mater. Eng., 16(12), 2021. https://doi.org/10.1186/s40712-021-00134-6
 Mastrone, M. N. & Concli, F., A multi domain modeling approach for the CFD simulation of multi-stage gearboxes. Energies, 15(3), p. 837, 2022. https://doi.org/10.3390/en15030837
 “OpenFOAM.” http://www.openfoam.com.
 “SALOME.” http://www.salome-platform.org.
 “Bash.” www.gnu.org/software/bash.
 Hirt, C. W. & Nichols, B.D., Volume of fluid (VOF) method for the dynamics of free boundaries. J Comput Phys, 39(1), pp. 201–225, 1981.
 Rusche, H., Computational Fluid Dynamics of Dispersed Two-Phase Flows at High Phase Fractions. Imperial College of Science, Technology and Medicine, London, 2002.
 Kunz, R.F., et al., Preconditioned Navier-Stokes method for two-phase flows with application to cavitation prediction. Comput. Fluids, 29(8), pp. 849–875.
 Höhn, B.R., Michaelis, K. & Otto, H.P., Influences on no-load gear losses. 3rd European Conference on Tribology, pp. 639–644, 2011.