ELUBSYS

Work Packages

WP1 will address the sealing element of bearing chambers. The objectives of WP1 are threefold:

• To investigate the performance of advanced brush seals for bearing chamber sealing. This work will test the endurance of the seals and measure frictional heat under different overlap conditions as well as rotational speeds. It will also study the impact of oil coking on the stiffness and efficiency of the seals. Performance testing will also include the measurement of air flow through the seals and their ability to prevent/reduce oil leakages from the chamber (via a leakage test involving the reversal of pressure difference).
• To study the two-phase flow behaviour, heat transfer and pressure loss in the scavenge pipe when brush seals are used and the vent pipes removed. In addition high speed camera techniques will be used to assess the flow pattern in the scavenge pipe. The impact on the flow and heat transfer will be assessed when the scavenge pipe is alternatively connected to a scavenge pump and to an ejector.
• To investigate the effect on bearing chamber thermal behaviour of the reduced air flow anticipated through brush seals compared to labyrinth and optimise the bearing chamber thermal design. Two case studies will take place, applying the modelling techniques developed in WP2. In the first, a CFD model of the bearing chamber investigated under the first objective will be created and the data compared to experimental data. This case study will verify the performance of the CFD code developed in WP2. In the second case study, a design optimisation will be performed with a CFD model and also a thermomechanical model of a real engine Tail Bearing Housing (TBH). Through a sensitivity analysis the benefits of advance sealing technologies when applied to a real component will be evaluated.

The underlying aims for this WP are to determine the suitability of brush seals as a replacement for labyrinth seals in bearing chambers, measure the reduction in deflected compressor air they can achieve and also to evaluate whether they can lead to the elimination of the vent pipes in bearing chambers.

This work package aims at better understanding and modelling the complex two-phase flows in bearing chambers, scavenge and vent ports, and adjacent pipes. It intends to establish CFD capability for realistic geometries typical for lubrication systems in gas turbines and produce new design rules which will enable lubrication systems that are better adapted to handle the new challenges of modern gas turbine engines.

The objectives can be summarised as follows:

• Improve scavenge and vent port performance.
• Develop and optimise CFD modelling strategy for two-phase flows in bearing chambers.
• Improve understanding of heat transfer in bearing chamber walls.
• Predict heat transfer in bearings during oil flow interruption.

The expected results will allow both, a more detailed understanding of flow and heat transfer phenomena and two-phase flow prediction capability. Correlations will be developed based on test results and CFD predictions to support the engine design process. The derived design guidelines for chamber ports are expected to support the engine design process to account for advanced technologies such as contra-rotating shafts for improved turbine performance, less fuel burn and green house gases. The methods developed in this WP will improve the prediction of oil content in bearing chamber outlet pipes. This will enable the design of innovative bearing chambers that deliver acceptable performance whether they are un-vented and use with tight seals (carbon or brush) or whether they are conventionally vented.

Externals mean here "elements of the oil system out of bearing chambers". This includes supply and scavenge systems and all the related components. The objective of this WP is to produce rules for these three different parts of the oil system in order to improve or optimise their performances and adapt them to the advanced bearing chamber architectures proposed in WP 1 and 2. These rules will be built through computational analysis and validated through test campaigns. The knowledge of supply systems is needed to deliver the exact oil flow under the best conditions (i.e. pressure, temperature, and flow) to the bearing chamber. Air concentration in inlet oil, supply pump and inlet circuit pressure drop can deeply influence the accuracy of the flow delivered in the engine bearings chambers which is conflicting with the engine manufacturers' expectations. The quantification and the modelling of this phenomenon will allow for a better delivered flow prediction in the whole range of engine operation and consequently respond with an improved precision to the new & more important heat management needs, e.g. higher flow, faster speed…

Further to the improvement that will be proposed by WP1, the scavenge system can also be reviewed and simplified. Heat management (WP2) will also drive the modification of the scavenge design and lead to new scavenge architectures. Several prototypes will be tested under real conditions to demonstrate the feasibility and the advantages of the improved scavenge systems.

Two new designs will be tested, driven by the main goal of mass reduction :

• A light and reliable scavenge system that allows evacuation of oil by single pumping element from two separate bearing chambers simultaneously.
• An ejector pump to replace the set of volumetric pumps.

The new designs proposed for the external oil system will be consistent with the overall project objectives. Each study will then be lead with the aim of:

• Reducing mass of simplified design.
• Decreasing SFC by using advanced sealing.

The objective of this WP is to:

• Develop and validate numerical methods of characterising and predicting oil ageing and degradation in complex aero-transmission systems.
• Develop a method and a device to monitor oil health in the engine.
• Develop an anti-coking coating.

• To coordinate all scientific and technical aspects of the project.
• To develop an overall global 0D Model for the lubrication system as evaluation tool.
• To optimise the gains achieved by ELUBSYS through a systematic evaluation of the results achieved in the WPs 1-4.

Dissemination:

• To demonstrate added value of the project to aeronautics industry (European and non-European aircraft and engine manufacturers).
• To promote standards and best practice in lubrication systems.
• To prepare aeronautics industry (including supply chain) to the integration of the technologies developed by ELUBSYS.
• To establish an efficient link with the ACARE Technology Platform and its objectives.

Exploitation:

• At global level: To ensure that the goals, results and achievements of ELUBSYS are in line with EU initiatives responsible for the strategic direction of the European aeronautics industry.
• At the project level: To develop exploitation plans for partners which will enable the technologies developed by ELUBSYS to be used outside of the laboratories and to reach higher TRL levels.