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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - INAFLOWT (INnovative Actuation Concepts for Engine/Pylon/Wing Separation FLOw Control (Design, Build and Wind Tunnel Test))

Teaser

Summary

Engines with high bypass ratio are more efficient than those with a smaller bypass ratio. However, the increasing nacelle diameter going along with this modification poses challenges for aircraft designers, as compliant with ground clearance regulations requires a close wing-engine coupling.
To avoid collision with the engine nacelle during take-off and landing a partial cut-back of the leading edge devices of a commercial passenger airplane wing is inevitable.
The problem being addressed in the INAFLOWT project is the local flow separation (and hence local lift reduction) due to the close coupling of the promising ultra high-bypass ratio engine to the wing.

This project is important to society since the local flow separation reduces the overall efficiency of the airplane. As a result, the fuel consumption is higher and therefore the cost of flying and the effects on the environment are harsh.
Alternative:
This project is important to society since the local flow separation reduces the overall efficiency of the airplane in the takeoff and landing phase. On the other hand, the use of ultra-high-bypass-ratio engine is a promising way for reduction of fuel consumption and reduction of environmental footprint of air transportation.

The overall objectives of the project are to overcome the local flow separation by means of applying innovative active flow control technology. This technology, developed by the 5 teams of researchers and validated by both extensive computational fluid mechanics and wind tunnel testing at two scales, is aimed to solve the local boundary layer separation at low energetic cost and low mass flow.

Work performed

List of objectives for the project as described in the DoA is provided. The achievement of which is described in breif.
1. Achieve in a small scale wind tunnel model similar flow conditions as in the baseline full scale model. Design, build and aerodynamically characterize an equivalent generic small scale baseline configuration without flow control through numerical analysis and WT test. Extensive computational studies, validated by wind tunnel data, enabled a detailed characterization of the flow topologies of the two experiments scales. The identification of similarities made it possible to investigate small scale model and to transfer the knowledge to full scale model case.
2. Overcome local flow separation using innovative AFC concept.
Design innovative actuation concepts to overcome the local flow separation. that will postpone the stall angle, increase the maximum lift and the maximum L/D as the benchmark AFC technology. This task was achieved by combined computational fluid dynamics (CFD) and small scale wind tunnel testing. Numerical and experimental parametric studies are ongoing to further improve the efficiency of the flow control devices.
3. Improve flow physics understanding. Validation of numerical results and synergistic analysis with simplified geometry test results to improve flow physics understanding of the proposed innovative actuation concept. The data from dedicated wind tunnel tests were used for validation of CFD computational results. High level of detail was considered. Validation of CFD results allowed to adapt the numerical setup toward best compromise between computational costs and physical accuracy.
4. Reach figure of merit greater than unity for innovative AFC configuration. Optimize effectiveness while maximizing efficiency through small scale WT testing of the innovative actuation concept. To be achieved in the second half of the project.
5. Provide near full-scale prototype innovative AFC hardware. Develop and manufacture hardware of the optimized actuation configuration for the large scale WT test. This is work in progress.
6. Reach TRL3 with innovative AFC system. Provide an aerodynamic proof of concept (TRL 3) of the innovative AFC concept at industrially relevant flow conditions through large scale WT tests. To be achieved in the second half of the project.
7. Benchmark other AFC concepts. Benchmark and validate potential improvements gained from on-going optimization processes of matured actuators already under development in Clean Sky 2, LPA, Platform 1, through large scale WT tests. To be achieved in the second half of the project.

Final results

The main innovation in the INAFLOWT project is the use of steady suction in addition to the already used pulsed blowing to achieve boundary layer attached flow. Steady suction is considered extremely effective flow control tool and its use is expected to significantly reduce the mass flow requirement from the pulsed blowing used further downstream.

The expected result until the end of the project is to experimentally demonstrate the innovative flow control concept in large scale wind tunnel testing and, in parallel, validate the numerical approach to enable further implementation of the technique to flight tests.

The potential impacts on aviation are huge, since the concept will allow optimization of the wing design for cruise flight with the knowledge that local problems such as ours could be handled with flow control without penalizing the cruise performance.