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Powered, modular Wind-Tunnel model for low and high Reynolds tests

Periodic Reporting for period 3 - POLITE (Powered, modular Wind-Tunnel model for low and high Reynolds tests)

Reporting period: 2019-01-01 to 2019-12-31

POLITE focuses on designing and building a WT-model for delivering aerodynamic data that allows to analyse the aerodynamic performance of innovative control surfaces and high-lift devices.
The model built in POLITE has been used in a low-Re WT. This first test-campaign delivered aerodynamic data of the baseline solution and already included the innovative control devices. Following the results from this first campaign a second campaign in a high-Re WT will be performed, in the framework of subsequent actions.
Indeed, the wind tunnel tests are not within the scope of POLITE but the model has been designed so that testing in the chosen test facilities can be performed. Therefore, shortly summarizing, POLITE:
• designed a WT-model that is powered and usable in both low and high-Reynolds test-campaigns
• developed solutions that increase test-efficiency
• manufactured the model
• prepare the WT-test campaign by planning the integration of the models into the WT and delivering solutions for the interfaces

POLITE contributed to validate the feasibility of an aerodynamic improved design developed by the JTI-CS2-REG consortium. It will therefore support the development of methods to increase aerodynamic performance and efficiency, resulting in a positive ecological impact. This helps fulfilling the ACARE goals and will support the competitiveness of the European aeronautic industry.
The magnitude of the expected impact can be appreciated considering the envisaged advantages to improve aerodynamic efficiency of small aircraft both in cruise and in High Lift Conditions. These aspects have a reasonable impact in terms of direct and indirect costs, making the aircraft of new generation a competitive product. Technical solutions regarding new movable surfaces' design here implemented, tested and validated are suitable and profitable for other business areas (aeronautical and non). It is therefore expected that this project will contribute to the development of European technical leadership in aircraft manufacturing and will increase competitiveness of EU companies on a worldwide market, helping in the realization of more efficient and less expensive aircraft.
Project partners IBK and DREAM are also supporting Universities by giving lectures. This impact goes beyond technical benefits/ impacts and produces social benefits by transferring knowledge to next generations of engineers.
The design for low-Re tests has been completed.
The designs of flap and flap-tab mechanisms have been completed. Laboratory tests demonstrated the design concept of inboard flap mechanism in CS2 configuration, while the final inboard flap design in LEGACY configuration has been demonstrated in the WT in October 2018.
The design of model components for high-Re tests is complete, including the integration of the pneumatic propulsion system. Notwithstanding a partial non-compliance of the material used to manufacture the wing, not ductile enough to fulfill all the requirements set out in the European regulations for components under pressure, wing panels and nacelle parts have been manufactured and assembled on time. Recovery actions to be implemented after the project closure have been discussed with JU and TM.
After the development of first design concepts, and review meetings with TM and WT, the final design and manufacture of the support system for high-Re tests has been subcontracted to a specialized company as a risk mitigation measure to ensure a successful high-Re test campaign, since the identified subcontractor developed a very similar system in the past. Activities were completed at the end of 2019. Interfaces with WT have been agreed, with new lower strut and connecting plate designed by POLITE.
Correction factors to account for the strut interference during WT tests have been calculated in low- and high-Re conditions. Data have been released to TM and included in project deliverables. First batch of results has been published at the ECCOMAS2018 in open access. The second batch of results was submitted for publication at the ECCOMAS2020, cancelled for the COVID-19 crisis.
The WT model for low-Re power-on tests has been completely manufactured, assembled, instrumented and installed in the WT (RUAG LWTE) for power-on WT tests. The three-week WT test campaign has been successfully completed in June 2019. News about the successful completion of the test campaign have been published on IBK and CS2JU websites.
Concerning exploitable results, the developed solutions for increasing WT test productiveness have a huge exploitation potential. Indeed, the developed solutions for flap actuation are very promising and have been already demonstrated in the WT, and results presented at the AERODAYS 2019, session A6. The presentation is accessible on the internet in open access.
Furthermore, the determination of strut influence corrections for powered configurations in both low and high Re conditions is playing a crucial role for the development of skills and the triggering of new business opportunities for the SMEs involved.
Beyond relevant progress with respect to the current state of art, POLITE designed and manufactured a model that is able to deliver aero-data in subsequent test-activities in two different Wind-Tunnels, one of them being a low-Re solution, one a high-Re solution. This requirement is sensible and not common especially in the case of the two WT used here (RUAG LWTE in combination with ONERA-F1). The technically ambitious part required here is that the model itself is powered and equipped with two different engines due to the existing infrastructure of the two WT. This would involve in general the design of two WT-models (at least w.r.t. to the critical components). On the contrary, POLITE designed a unique modular WT model suitable for the purpose of the present activity, by complying with requirements coming from different wind tunnels and infrastructures. This requires consolidated capabilities in wind tunnel model design associated to a consolidated experience in wind tunnel testing and engine propulsion systems.
Experimental tests on scaled complete A/C model typically use unpowered engines providing only main aerodynamic characteristics without simulating the interference between the propulsion system and both the airframe and aerodynamic surfaces. Moreover, modern computation methods are mainly based on ideal fluid theory, and are not able to fully reveal and take into account the above-mentioned effects. Experimental activities are therefore the main way to study the problems of Propellers and airframe interaction and in particular to assess the magnitude of the aerodynamic interference, to understand the aerodynamic phenomena associated with the installation, and to develop an analytical and experimental data base for numerical comparisons.
From a project point of view, the project delivered innovative technologies suitable for WT-testing. Although wind tunnel models are sometimes tested in different WT, this option is often not available for models equipped with powered engines. POLITE therefore enabled such tests and delivered ideas to design a model in a way to reduce the number of parts. Although of minor relevance this also increases the ecological performance. Another strong argument for this approach is the reduction of model development time, the reduction of development cycle time and a strong cost-reduction, since only one model is needed.
Motorized Flap during WT test demonstration
Rotary Shaft Balance
Model during WT test preparation activities
"WT Model view #3, powered configuration"
WT model in RUAG LWTE, first WT test campaign power-off
"WT Model view #1, unpowered configuration"
"WT Model view #2, unpowered configuration"