Planet ROlling Bearing with Advanced TEchnologies

Informations projet

PROBATE

N° de convention de subvention: 738029

DOI

10.3030/738029

Projet clôturé

Date de signature de la CE 16 Decembre 2016

Date de début 1 Janvier 2017

Date de fin 31 Decembre 2022

Financé au titre de

• SOCIETAL CHALLENGES - Smart, Green And Integrated Transport

Coût total

€ 771 615,00

Contribution de l’UE

€ 498 246,00

Coordonné par

SKF AEROSPACE FRANCE
France

Periodic Reporting for period 4 - PROBATE (Planet ROlling Bearing with Advanced TEchnologies)

Période du rapport: 2021-07-01 au 2022-12-31

Résumé du contexte et des objectifs généraux du projet

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.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The PROBATE project focused on a design of a planet bearing for Power gearbox application.

In this project frame, a Hybrid Spherical Roller bearing design solution was developed. Well-known design criteria are currently challenged in order to reach the space envelop and loading conditions targeted.
For such purpose, activities on numerical modelling was performed implicating SKF simulation tools and a CFD (Computational Fluid Dynamic) tool. The complementary of tools allowed the evaluation of the bearing dynamic, lubricant and thermal behavior supporting the development of the detailed bearing design.

On the bearing technologies side, the new technologies development reached the adequate maturity level for the implementation in the bearing demonstrators.
For that purpose, a focus has been put on ceramic rolling elements introduction and on the bearing rings material processes setup up definition.

Some bearing prototypes were manufactured and the testing evaluation could be prepared.
The testing campaign was put in place in SKF testing facilities in the last part of the project in order to assess the planet bearing design and technologies.
It could put in evidence the good behavior of the designed bearing and confirm the the performance advantage of hybrid technologies compared to a full steel version.
The testing data could also be used to validate the methodology and the models used for the simulation approach.
And finally, with the deployed testing campaign, degradation mode of the hybrid bearing prototypes could be evaluated.

The simulation approach implicated the CFD and the challenges encountered were reported and disseminated.
The results of the testing campaign correlated to simulation data will be exploited for other research activities regarding power loss assessment, contributing to continuous improvement of assessment methodology.
And finally, the developed planet bearing corresponds to maturity milestone for this type of design and for the corresponding Power gearbox architecture.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The main impact of this project is to be able to propose a hybrid planet bearing design and the corresponding technologies for the development of Power gearboxes.

The main objective and results concern first of all the direct exploitation of cutting edge rolling bearing technologies (newly developed materials ceramics rolling elements) and performance/design possibilities
The testing campaign on prototypes demonstrated good behavior of this type of bearing in normal and degraded conditions.
Such bearing with lower power losses will directly contribute to engine efficiency with a reduction of fuel consumption and CO2/NOX emissions.
More resistant bearings to harsh environment, such as particle contaminated oil, will be also more reliable. They could become a contributor to the improvement of engine maintenance interval providing positive environmental and economic impacts.

In addition, continuous improvement in terms of planet bearing numerical model able to predict heat generation and transfer considering interactions between dynamics, lubricant and thermal behaviors, directly contribute more efficient bearing design and finally to engine efficiency with a reduction of fuel consumption and CO2/NOX emissions.

The above characteristics could therefore bring some competitive advantages for planet bearing applications where this type of bearing is needed.
It is also possible to note that the developed technologies in this project (material and numerical models) can be transferred, like elementary bricks, to improve design and performances for other applications, for which efficiency and resistance to harsh environment are also key factors.