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Performance and qualification tests of lubrication system equipment

Final Report Summary - LUBEST (Performance and qualification tests of lubrication system equipment)

Executive Summary:
The global objective of LuBest is to upgrade the aero-engine lubrication test bench ATM-01 of ULB to an oil pressure of 27 bar and an oil temperature of at least 200°C with a standard engine oil Jet Oil Type II or an upgraded oil called HTS (High Thermal Stability). This should first be done for pure oil flow conditions but also, after that, for air-oil (2-phase) flow conditions that are representative of real lubrication systems of new and future turbofans and turboprops (as the Open Rotor Engines, UHBPR or Geared Turbofans GTF). This upgrade of the ULB lubrication test bench must be validated with tests of oil pumps in test conditions that are representatives of modern and future aero-engines.
Phase 1 of the project is with pure lubrication oil and must be validated through characterization and endurance testing of typical aero-engine lubrication feed pumps in unpreceeded working conditions (for oil pressure, temperature and mass flow rate).
Phase 2 of the project is with two-phase flow conditions (oil and air in various mixture ratio's) and must be validated through characterization and endurance testing of typical aero-engine oil scavenge pumps. Innovative oil pump configurations must also be tested in the frame of this LuBest project.
Project Context and Objectives:
Through the whole project, the objectives for the LuBest project between TM (Topic Manager) and ULB-ATM have regularly been reviewed and finally approved between the different parties. All objectives are fully reached at the end of the project, even if with some delay compared with the original timetable of the complete project. The project duration had been finally fixed at 51 months with an end date on 30 June 2015.
The main achievement is the availability of an updated test bench (called ATM-01) with a capacity for pure oil testing and a capacity for two-phase air-oil flow testing at a TRL5 / TRL6 level, depending on the lubrication system components to be tested.
The global objective of LuBest was to evaluate the technical feasibility of an upgrade of the oil flow test bench ATM-01 of ULB to an oil pressure of 27 bar and an oil temperature of at least 200°C with the standard Jet Oil Type II or an upgraded oil standard.
This had to be done for pure oil flow conditions and also for the challenging air-oil (two-phase) flow conditions representative of real aero-engine lubrication systems of new and future turbofans, turboprops and turboshafts. This final report relates the upgrades done for the ATM-01 test bench and the validation results obtained in the LuBest project.
The basic document for the LuBest project description is the technical specification document « 57DV184795.9003 » issued by the TM to the attention of ULB-ATM.

In the two first reporting periods, the following tasks have been performed:
- New design of the test bench and selection of the components to increase the capabilities (oil pressure and temperature) of the test bench ATM-01 in order to run tests with a higher level of the oil (counter) pressure to mimic the behavior of the recent aero-engine developments in pure oil conditions.
- Implementation of this 1st upgrade in order to run some characterization tests and some endurance tests of aero-engine oil pumps in these updated pure oil conditions. All hardware and software modifications of this phase of LuBest have been implemented by ULB-ATM, after formal approval by TM. First real characterization tests in these updated working conditions have been successfully run on the upgraded ATM-01 test bench.
- Preparation of the 2nd update of the ULB test bench for an air-oil mixture at the entrance of the pump (type “scavenge pumps”) instead of pure oil (type “feed pumps”) in a large range of well-controlled air-oil ratio hot mixtures. This has been discussed between the TM and ULB-ATM, the technical specifications fixed, the test plan discussed, fixed and approved and all technical upgrades proposed by ULB-ATM have been approved by the TM.
During th least reporting period until month 51, we finalized the project by doing:
- Complete implementation of this 2nd update of the ATM-01 test bench for two-phase flow working conditions. This 2nd upgrade of the ULB ATM-01 test bench is intended to perform characterization and endurance testing of any type of new / innovative aero-engine scavenge oil pumps with a well controlled two-phase flow at the entrance of the pump.
- Extensive validation tests in two-phase flow working conditions at high oil temperature and counter-pressure with current state-of-the-art aero-engine lubrication pumps have also been performed during this final period of the project.
Project Results:
The test bench is fully operational for pure oil and two-phase flow working conditions for the increased temperature, pressure and mass flow rates that were given as objective at the beginning of the project. That makes the test bench of ULB a candidate to test any new and future aero-engine lubrication component in any new development of turbofans and turboprops.
To test the quality and in accordance with the TM specifications of the new ULB ATM-01 test set-up, an extended test campaign has been realized at the end of the final reporting period by ULB in the upgraded two-phase flow conditions.
The main parameter to characterize a pump is its efficiency, defined as the ratio of the measured flow rate over its theoretical flow rate.
During the characterization tests of the pump in the new two-phase flow conditions, on top of these volumetric pump efficiency measurements, a check was done, at the same time, to observe:
- The stability of the operating conditions;
- The accuracy and reproducibility of the measurements;
- The feasibility to obtain the right mixture of oil and air flow;
- The feasibility to control a fixed ratio air/oil;
- And the feasibility to warm up the mixture of oil and air.
These validation tests were performed for two different values of the rotation speed of the pump, for a fixed oil temperature and a fixed air/oil ratio. The oil pressure at the inlet and outlet of the pump were variable parameters. These tests were performed several times to test the reproducibility of the measurements.
These validation tests have been performed very successfully and without any technical problems on the ULB-ATM test bench in these new two-phase flow conditions. This means a quite significant upgrade for the ATM-01 test bench of ULB and mainly for its industrial users who want to characterize state-of-the-art and innovative lubrication system components and to accelerate their process in qualifying and certifying these products for aero-engine manufacturers. These two-phase flow test results are further described in the technical deliverables.

Potential Impact:
Thanks to the LuBest project, ULB-ATM developed and made available an upgraded oil test bench that is able to test all lubrication system components of any modern and future aero-engine in the most challenging working conditions using pure oil flows or using air-oil two-phase flows.
This test bench is available for the aero-engine manufacturers and their suppliers to test oil system components for characterization testing of endurance testing.
This has been extensively disseminated through conference papers, journal papers and oral presentations by the ULB-ATM research team.
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