Comparison of single- vs. multi-phase simulations of a gearbox and importance of windage effects

摘要

Computational Fluid Dynamics (CFD) has accustomed itself as one of the most important Computer Aided Engineering (CAE) tools in the modern industry. Its reach covers a wide spectrum of areas ranging from external aerodynamics to polymer flows in electronic nano-components. Despite the widespread use of classical Finite Volume (FV) method of CFD, it still fails to provide satisfactory solutions to some industrial problems. More specifically it clearly shows its deficiencies in the area of power-train and gear-train related flow simulations. For these purposes the cumbersome pre-processing requirements, and computationally expensive numerical methods are negatively influencing the desired design turn-around time. In order to at least partially mitigate the computational cost, many codes attempt to use single phase simulations. In this work we show the importance of windage effects for a generic gearbox, and demonstrate that air phase cannot be left out and that its presence is crucial for accurate representation of the flow field, especially at higher RPM. We perform the simulations using the nanoFluidX SPH code, developed by FluiDyna GmbH. The main advantage of nanoFluidX over the more classic FV CFD methods is that the SPH method it uses is Lagrangian in nature, therefore eliminating the need for meshes and associated time consuming efforts on both user and computational sides. nanoFluidX allows for truly multi-phase simulations, capturing all the relevant physics of the flow, at a fraction of a time required for a classic FV CFD approach.