The development of Ultra High Propulsive Efficiency (UHPE) engine is a key factor to fulfil the main milestones of the Engine ITD program. From an engineering point of view, the significant environmental benefits of this new engine are synonymous with the introduction of the Ultra High Bypass Ratio (UHBR) technology. Current engine designs are indeed reaching their limits in terms of efficiency. This is why innovative architectures like the geared turbofan concept that decouples fan and turbine speeds by means of a high- Power GearBox (PGB) are the promising enablers for UHPE engine success.
This PGB introduction raises different technological challenges at the system and component scales: PROBATE project will focus on the planet bearing component, the central module of the transmission system of the gearbox.
In terms of engine performance, the design, sizing and capacities of the planet rolling bearings can affect the whole engine architecture. The rolling bearings have been clearly identified as crucial components with respect to reliability.
Nowadays, new engine architecture developments are possible only if they take into account new technologies and developments for engine’s component parts.
The main scope of PROBATE project is “to predict bearing behavior (through dynamic, lubrication & thermal modelling) and develop planet rolling bearing technologies, overcoming current design rules of aero-engine bearings enabling the development of a UHPE engine (or other high performance architectures)”.
PROBATE project also contributes to the raising of the TRL of the proposed bearing technologies, meaning that the overall whole engine system reaching TRL6.
PROBATE is full in line with the Clean Sky 2 program, since it will support the key Societal Challenge. It will enable cutting edge bearing solutions for further gains in decreasing fuel burn, CO2, NOX, noise emissions and strongly contribute to the renewed ACARE SRIA. PROBATE proposers are committed to support future global leadership of the European aeronautical industry supply chain, creating jobs through and reinforced competitiveness.
The new bearing technologies to be developed in PROBATE had the following specific objectives:
- To develop and provide a new numerical model able to predict heat generation and transfer in the planet bearing taking into account interactions between dynamics, lubricant and thermal behaviors.
- To demonstrate a -30% in power loss & oil flow and a -15% of the bearing weight in comparison to a baseline solution.
- To develop and provide an optimized rolling element profile, an optimized lubrication solution as well as their integration in the new planet bearing.
For such objectives, a Hybrid Spherical Roller bearing design was developed, manufactured and tested providing a development maturity milestone for this type of bearing for PGB application.
Two complementary numerical models were put in place with SKF BEAST, bearing dynamic simulation tool, and with a CFD (Computational Fluid Dynamics) tool and a testing campaign was put in place to evaluate the performance in two conditions.:
- In normal operating conditions in which performances are assessed and correlated to simulation results
- In degraded conditions in which bearings prototypes are pre-damaged in order to analyze bearing degradations.
