Periodic Reporting for period 3 - BISANCE (Biphasic Heat Transport integration for efficient heat exchange within Composite materials Nacelle)
Reporting period: 2022-04-01 to 2023-05-31
The project intends to test in icing wind tunnel (IWT) one demonstrator of engine air intake integrated in a nacelle and equipped with an innovative biphasic heat transport system for regenerating the energy from the oil of the engine. The objective, by testing the technology in a representative environment, is to reach TRL5. At the end of the project the technology will be able to be further developed towards TRL6 to 9 with the final aim to be transferred to the aeronautic value chain.
The ambition of the project is to demonstrate the possibility to use the energy from the engine oil for protecting the engine air intake against the ice accretion. To make sure that the oil is sufficiently cooled down in all the environmental conditions, even the warmest ones, aircraft on the ground for example, a significant area of the nacelle will be used as a heat exchange surface additionally to the ice protected surface.
The perspective of this heat exchange concept is to optimize the existing system architecture by removing the active cooling system for the oil, removing the active ice protection system, and to harvest the energy from the oil to regenerate it for the ice protection purpose.
The project has concluded with a partial success. The capillary jet loop was manufactured, tested within a reduced scale specimen and finally tested in a full scale specimen in icing wind tunnel. The results have shown than passive ice protection was feasible. The analysis of the test results of the project combined with the numerical investigations have highlighted that removing the active oil cooling system was not possible but a capillary jet loop could help reducing the size and weight of the current active systems.
The ambition of the project is to demonstrate the possibility to use the energy from the engine oil for protecting the engine air intake against the ice accretion. To make sure that the oil is sufficiently cooled down in all the environmental conditions, even the warmest ones, aircraft on the ground for example, a significant area of the nacelle will be used as a heat exchange surface additionally to the ice protected surface.
The perspective of this heat exchange concept is to optimize the existing system architecture by removing the active cooling system for the oil, removing the active ice protection system, and to harvest the energy from the oil to regenerate it for the ice protection purpose.
The project has concluded with a partial success. The capillary jet loop was manufactured, tested within a reduced scale specimen and finally tested in a full scale specimen in icing wind tunnel. The results have shown than passive ice protection was feasible. The analysis of the test results of the project combined with the numerical investigations have highlighted that removing the active oil cooling system was not possible but a capillary jet loop could help reducing the size and weight of the current active systems.
Conceptual, preliminary, detailed and testing phases were completed on the system and its integration into the engine nacelle structure. For the final selection of the system concepts integration, various specimens were manufactured and analyzed. Finally, tests on reduced scale specimens were performed for the assessment of the system prior to the final test done on a full-scale specimen in early 2023.
Along the first phase of the project, various system integration concepts into the structure were proposed.
Three integration concepts were proposed:
✓ Metallic panels
✓ Metallic additive manufacturing process
✓ Composite
Several biphasic system architectures were proposed and a trade off was done. The needed heat transfer to comply with both functions of the biphasic system was widely investigated (oil cooling and ice protection). All the flight phases were considered and the most critical conditions for both functions were highlighted.
One of the main conclusions on the power analysis is that the current active oil cooling system cannot be fully removed because the amount of heat to be extracted is too significant.
Reduced scale tests were prepared to anticipate the behaviour of the complete biphasic loop and to limit the risk of failure during the final demonstration in icing wind tunnel. The system loop was tested on a bench and the amount of heat exchanged was measured. Also, the system loop was qualified to check its adequate operation like simulating the rolling and the pitching effects of the aircraft.
Following the preliminary analysis and the reduced scale tests, the detailed design of the full-scale specimen was completed. The test article was manufactured featuring both ALM metallic and composite heat exchangers. The system loop was fully integrated into the mock-up nacelle, featuring the lines, for the fluid transportation as well as the heat exchanger between the oil and the fluid inside the loop. Outside of the test article, an oil test bench was manufactured to reproduce the engine hot oil of an operating engine. The oil was used as the hot source of the system. The equipment was sent to the icing wind tunnel where the specimen was confronted to extreme icing conditions down to -30°C and strong winds of 350 km/h.
The analysis of all tests and investigations concluded that the ice protection of the engine inlet using the developed passive system loop is efficient and that the use of the system to cool down the engine oil is efficient but does not allow to remove completely the existing active cooling system. Beyond the test analysis, the project was concluded with the establishment of a final system design as well as a thermal model. The promising results have conducted to a new project to test the integration of such a system into a real engine environment that will allow to increase even more the maturity level of the capillary loop. The interesting results and analysis done along the project were disseminated to a targeted audience through various conferences (ILA Berlin, IHPC conference or the Coock fighting icing project).
Along the first phase of the project, various system integration concepts into the structure were proposed.
Three integration concepts were proposed:
✓ Metallic panels
✓ Metallic additive manufacturing process
✓ Composite
Several biphasic system architectures were proposed and a trade off was done. The needed heat transfer to comply with both functions of the biphasic system was widely investigated (oil cooling and ice protection). All the flight phases were considered and the most critical conditions for both functions were highlighted.
One of the main conclusions on the power analysis is that the current active oil cooling system cannot be fully removed because the amount of heat to be extracted is too significant.
Reduced scale tests were prepared to anticipate the behaviour of the complete biphasic loop and to limit the risk of failure during the final demonstration in icing wind tunnel. The system loop was tested on a bench and the amount of heat exchanged was measured. Also, the system loop was qualified to check its adequate operation like simulating the rolling and the pitching effects of the aircraft.
Following the preliminary analysis and the reduced scale tests, the detailed design of the full-scale specimen was completed. The test article was manufactured featuring both ALM metallic and composite heat exchangers. The system loop was fully integrated into the mock-up nacelle, featuring the lines, for the fluid transportation as well as the heat exchanger between the oil and the fluid inside the loop. Outside of the test article, an oil test bench was manufactured to reproduce the engine hot oil of an operating engine. The oil was used as the hot source of the system. The equipment was sent to the icing wind tunnel where the specimen was confronted to extreme icing conditions down to -30°C and strong winds of 350 km/h.
The analysis of all tests and investigations concluded that the ice protection of the engine inlet using the developed passive system loop is efficient and that the use of the system to cool down the engine oil is efficient but does not allow to remove completely the existing active cooling system. Beyond the test analysis, the project was concluded with the establishment of a final system design as well as a thermal model. The promising results have conducted to a new project to test the integration of such a system into a real engine environment that will allow to increase even more the maturity level of the capillary loop. The interesting results and analysis done along the project were disseminated to a targeted audience through various conferences (ILA Berlin, IHPC conference or the Coock fighting icing project).
The biphasic system developed proposes a unique passive solution in terms of ice protection of the air intake.
The investigations carried out as well as the test characterization done on simplified coupons, reduced-scale specimens and full-scale test articles have shown that the current active oil cooler system could be significantly downsized using a biphasic system resulting in valuable power savings.
Also, a huge effort has been brought to the integration of the system into the structure of the nacelle. Three concepts of integration have been investigated:
- An additive manufacturing process, allowing a full integration of the system tubing within the inlet structure. Such a technology enables the optimisation of the system integration design leading to the realization of complex architecture and the optimization of the overall weight. The results have demonstrated that an ALM part can be manufactured with a high level of quality, showing no leakage (below 10^-8 mbar.L/s ), surface accuracy of 0.5mm and tremendous possibilities for a complex design and optimized weight.
- An advanced metallic structure, featuring channels for the fluid circulation. The metallic sheets were chemically machined to create the channels. To ensure the airtightness of the channels, the metallic sheets were welded together. Even if the small coupons showed promising results, trials on larger specimens were more difficult. The welding process on large scale components should be more investigated in the future.
- A composite structure. Aluminum tubes were cured together with carbons fiber plies. The composite heat exchanger showed very good quality, the shape of the final part showed no distortion with a surface accuracy of +/- 0.5mm.
Modifying an aluminium structure into a composite nacelle would decrease the weight by 50% for a similar structural resistance.
Replacing the classical Air Cooling Oil Cooled System and the active ice protection system will lead to another weight saving.
Substituting the active systems (oil cooling and ice protection systems) by the biphasic passive system will permit to save around 100kW of power per A/C.
Globally, combining all the above effects, the objective is to save 25kg and 889 000kg of CO2 emissions per A/C along its life.
Also, the fuel saving will decrease the operational costs by 200 000$ for each A/C compared to a similar A/C with current technologies.
The investigations carried out as well as the test characterization done on simplified coupons, reduced-scale specimens and full-scale test articles have shown that the current active oil cooler system could be significantly downsized using a biphasic system resulting in valuable power savings.
Also, a huge effort has been brought to the integration of the system into the structure of the nacelle. Three concepts of integration have been investigated:
- An additive manufacturing process, allowing a full integration of the system tubing within the inlet structure. Such a technology enables the optimisation of the system integration design leading to the realization of complex architecture and the optimization of the overall weight. The results have demonstrated that an ALM part can be manufactured with a high level of quality, showing no leakage (below 10^-8 mbar.L/s ), surface accuracy of 0.5mm and tremendous possibilities for a complex design and optimized weight.
- An advanced metallic structure, featuring channels for the fluid circulation. The metallic sheets were chemically machined to create the channels. To ensure the airtightness of the channels, the metallic sheets were welded together. Even if the small coupons showed promising results, trials on larger specimens were more difficult. The welding process on large scale components should be more investigated in the future.
- A composite structure. Aluminum tubes were cured together with carbons fiber plies. The composite heat exchanger showed very good quality, the shape of the final part showed no distortion with a surface accuracy of +/- 0.5mm.
Modifying an aluminium structure into a composite nacelle would decrease the weight by 50% for a similar structural resistance.
Replacing the classical Air Cooling Oil Cooled System and the active ice protection system will lead to another weight saving.
Substituting the active systems (oil cooling and ice protection systems) by the biphasic passive system will permit to save around 100kW of power per A/C.
Globally, combining all the above effects, the objective is to save 25kg and 889 000kg of CO2 emissions per A/C along its life.
Also, the fuel saving will decrease the operational costs by 200 000$ for each A/C compared to a similar A/C with current technologies.