Periodic Reporting for period 2 - ESTRO (Experimental and theoretical aSsessmenT of laminaR flow rObusteness at high mach and reynolds numbers)
Période du rapport: 2020-10-01 au 2022-12-31
The use of innovative load control & actuation devices, composite materials and natural laminar flow have been recognised as key technologies which may lead to significant improvement in aircraft performances and safety by increasing the flight envelope, lowering weights and reducing skin friction drag in cruise conditions, with the consequent reduction of pollutants emissions. ESTRO project contributed to this target by providing support to the CS2-REGIONAL domain driven by LEONARDO Aircraft with an experimental wind tunnel test campaign, at low and moderate Mach numbers, on the elastic NLF wing of the TP90 A/C equipped of morphing devices for high lift and load control and by predicting numerically the aerodynamic and laminar flow performance at flight Reynolds numbers. The outcome provides results and knowledge for future comparisons with other projects involving wind tunnel experiments, flight tests and computational results.
The objectives of ESTRO were thus twofold:
1) Design, optimise and perform the WT test campaign according to the topic requirements focusing on experimental measures of the aerodynamic loads, wing performance and laminar flow robustness
2) Perform the extrapolation of these measurements to flight conditions by using accurate and tuned numerical CFD tools.
The organisation of the project followed a specific framework where activities were grouped together into different WPs according to the specific objectives to be reached.
Figure 1 shows the work-breakdown structure of the project, which was divided into 3 Work Packages, each one dedicated to a specific action/objective. In particular WP1 was dedicated to the “Management” of the project, WP2 focused on the “Wind-Tunnel testing” activities, while WP3 was concerned with “CFD analysis”.
The objectives of ESTRO were thus twofold:
1) Design, optimise and perform the WT test campaign according to the topic requirements focusing on experimental measures of the aerodynamic loads, wing performance and laminar flow robustness
2) Perform the extrapolation of these measurements to flight conditions by using accurate and tuned numerical CFD tools.
The organisation of the project followed a specific framework where activities were grouped together into different WPs according to the specific objectives to be reached.
Figure 1 shows the work-breakdown structure of the project, which was divided into 3 Work Packages, each one dedicated to a specific action/objective. In particular WP1 was dedicated to the “Management” of the project, WP2 focused on the “Wind-Tunnel testing” activities, while WP3 was concerned with “CFD analysis”.
The final status of ESTRO activities, although not perfectly matching the original planned actions, can be considered satisfactory considering the difficulties faced by the consortium in terms of WT selection, late provision of the WT model and malfunctions of some of its components during the experimental campaign and considering the unavailability of some inputs necessary for the successful achievement of the project targets. Overall, 100% of the activities planned, revised and agreed with the PM were completed. The implemented mitigation actions, the constant interaction with PM and PO and the realignment of the activities according to the availability of data/inputs produced a positive impact with the consequent achievement of most of original objectives. Some targets could not be fully reached for the failure of the laminar-transition measurements during the WT campaign (due to a not appropriate surface preparation of the model not manufactured by ESTRO) and for the lack of a structural model of the wing for the FSI calculations. Nevertheless, once faced with the difficulties, the consortium reacted promptly, interacting with both PM and PO to recalibrate and realign the actions in relation to the achievable objectives, minimising the deviations from the original plan.
The identified solution for the WT provider, with the launch of the amendment to include DNW as new beneficiary and the realignment of the activities over 45 months, had a positive impact on the project, boosting the design and manufacturing process of the model (in charge to other consortia) and reducing risks associated with the model acceptance. The addition of the new beneficiary (DNW) to the project contributed to relieve some weakness of the initial proposal, mitigating the risks related to the launch of a European call for tender and including inside the consortium the specific knowhow necessary to design, optimise and perform an experimental campaign in a large WT facility. This positively contributed to solve several technical issues related to the functionality of the model and to the completion of the experimental campaign which was performed in the DNW LLF Wind Tunnel in December 2021 (figure 2). Numerical analysis and extrapolation of the experimental data added insights, increasing the output value of the project. In this respect, the approach chosen by ESTRO to perform the CFD campaign and the extrapolation of the experimental data to flight conditions proved its efficacy, identifying the possible reasons for the observed mismatch between the experimental and numerical data and providing a) a theoretical and quantitative explanation for the failure of the laminar-turbulent transition measurements b) a guideline on the quality of the surface finish level (in terms of surface imperfection characteristics) to achieve extended laminar flow in both WT and flight conditions, c) an extrapolation of the aerodynamic performance of the WT model to cruise conditions d) the evaluation of the robustness of CFD results with respect to the adopted turbulence model through an Uncertainty Quantification analysis (figure 3) e) a study of the effects of the Reynolds number on the extension of the laminar flow over the wing (figure 4) f) an estimation of the impact of the model deformation (figure 5) on the aerodynamic performance and g) an analysis of the detrimental effects of the propeller wake on the laminar flow extension in flight conditions (figure 6) .
The innovations and achievements of ESTRO were promoted through three main communication channels, that are: 1) the project website, 2) the participation to scientific congresses/workshops and the publication of scientific papers and 3) Consortium internal meetings. The website www.estro diin.unisa.it designed, hosted and maintained by UNISA, is available for public access, giving an overview of project objectives, significant results and main news and events. A detailed Plan for the Communications, Dissemination and Exploitation (PEDR) was designed and released by DREAM.
The spread of the Covid-19 pandemic and the compression of the efforts in the last months of the project led to a slowdown of the dissemination activities determining some changes to the original plan. Two conferences were attended (WCCM-ECCOMAS 2020 and 11th EASN Conference 2021) and two scientific papers published. The internal dissemination among the Consortium partners was guaranteed by bi-weekly informal meetings. In order to promote the dissemination and foster the collaboration of the different members of the consortium, seminars on advanced CFD techniques, were also organised at UNISA.
The identified solution for the WT provider, with the launch of the amendment to include DNW as new beneficiary and the realignment of the activities over 45 months, had a positive impact on the project, boosting the design and manufacturing process of the model (in charge to other consortia) and reducing risks associated with the model acceptance. The addition of the new beneficiary (DNW) to the project contributed to relieve some weakness of the initial proposal, mitigating the risks related to the launch of a European call for tender and including inside the consortium the specific knowhow necessary to design, optimise and perform an experimental campaign in a large WT facility. This positively contributed to solve several technical issues related to the functionality of the model and to the completion of the experimental campaign which was performed in the DNW LLF Wind Tunnel in December 2021 (figure 2). Numerical analysis and extrapolation of the experimental data added insights, increasing the output value of the project. In this respect, the approach chosen by ESTRO to perform the CFD campaign and the extrapolation of the experimental data to flight conditions proved its efficacy, identifying the possible reasons for the observed mismatch between the experimental and numerical data and providing a) a theoretical and quantitative explanation for the failure of the laminar-turbulent transition measurements b) a guideline on the quality of the surface finish level (in terms of surface imperfection characteristics) to achieve extended laminar flow in both WT and flight conditions, c) an extrapolation of the aerodynamic performance of the WT model to cruise conditions d) the evaluation of the robustness of CFD results with respect to the adopted turbulence model through an Uncertainty Quantification analysis (figure 3) e) a study of the effects of the Reynolds number on the extension of the laminar flow over the wing (figure 4) f) an estimation of the impact of the model deformation (figure 5) on the aerodynamic performance and g) an analysis of the detrimental effects of the propeller wake on the laminar flow extension in flight conditions (figure 6) .
The innovations and achievements of ESTRO were promoted through three main communication channels, that are: 1) the project website, 2) the participation to scientific congresses/workshops and the publication of scientific papers and 3) Consortium internal meetings. The website www.estro diin.unisa.it designed, hosted and maintained by UNISA, is available for public access, giving an overview of project objectives, significant results and main news and events. A detailed Plan for the Communications, Dissemination and Exploitation (PEDR) was designed and released by DREAM.
The spread of the Covid-19 pandemic and the compression of the efforts in the last months of the project led to a slowdown of the dissemination activities determining some changes to the original plan. Two conferences were attended (WCCM-ECCOMAS 2020 and 11th EASN Conference 2021) and two scientific papers published. The internal dissemination among the Consortium partners was guaranteed by bi-weekly informal meetings. In order to promote the dissemination and foster the collaboration of the different members of the consortium, seminars on advanced CFD techniques, were also organised at UNISA.
The activities (experimental and numerical) performed by the ESTRO consortium, will contribute to support the CS2-REGIONAL plan driven by LEONARDO and will find implementation in the future Regional Turboprop aircraft. The outcomes in terms of data and knowledge will serve for future comparison with other projects involving wind tunnel experiments, flight tests and computational results.
The magnitude of the expected impact is related to the envisaged, but realistic, advantages to improve the aerodynamic performances of the new regional turboprop aircraft. ESTRO project contributed to this target by performing an experimental wind tunnel test campaign and by predicting numerically the aerodynamic and laminar flow performances at flight Reynolds numbers. The outcomes of the project will help improving the procedure for the design of smart wings for the next generation turboprop aircrafts by better predicting laminar flow performance, LC&A effectiveness, loads and aerodynamics characteristics.
The magnitude of the expected impact is related to the envisaged, but realistic, advantages to improve the aerodynamic performances of the new regional turboprop aircraft. ESTRO project contributed to this target by performing an experimental wind tunnel test campaign and by predicting numerically the aerodynamic and laminar flow performances at flight Reynolds numbers. The outcomes of the project will help improving the procedure for the design of smart wings for the next generation turboprop aircrafts by better predicting laminar flow performance, LC&A effectiveness, loads and aerodynamics characteristics.