Advances and applications in comprehensive Gearbox Aero-thermodynamics and tribology simulation

The current status of an ongoing effort to develop a comprehensive gearbox aero-thermodynamics and tribology simulation tool, named PSULOL, applicable to both well-lubricated and loss-of-lubrication operation is presented. PSULOL employs a multi-scale approach, wherein various physical effects including: meshing tribology, convection heat transfer within the system and to the environment, high-frequency thermodynamic effects induced by the gear meshing frequency, and the long-time response of the overall gearbox temperature to a net imbalance of heat generation and transfer to the environment are simulated separately and coupled with one another iteratively through appropriate boundary and initial conditions. As established in 2014, the first-generation version of PSULOL was the first computational fluid dynamics-based (CFD-based) tool coupled with an all-lubrication regime tribology model capable of simulating transient loss-of-lubrication failure of high-speed gearboxes. This first version was built on an in-house research CFD code, NPHASE-PSU, and relied on a number of physical simplifications, particularly with regard to the geometric configuration of the housing, and to the effects of the coupling between multiphase flow within the system (retained lubricant dynamics) and meshing tribology. Here, present efforts underway to increase the physical fidelity and ease-of-use of PSULOL are outlined, and progress toward simulating physically-realistic gearbox configurations is shown. This includes modeling the disperse multiphase flow of lubricant droplets and film within the system, and transitioning from NPHASE-PSU, an in-house research CFD code, to Star- CCM+, a commercial code that is more user-friendly and features additional geometry-handling capabilities.