In the first reporting period of the DISPROP project the technical work was concentrated on the subobjectives 1) and 2). At the start of the project, design requirements for a generic distributed propulsion aircraft were worked out in cooperation with the project’s Topic Manager (TM). For this purpose, the TM provided the consortium with data from the reference aircraft, mission data, design constraints, and a test matrix based on the wind tunnel limits of GroWiKa (TUB) and DNW-NWB. Based on this data, the consortium determined a design for the distributed propulsion aircraft and scaled it down to wind tunnel model sizes (documented in deliverable D1.1).
Instead of investigating two or three propeller-wing configuration setups as suggested in the DoA, the focus of Phase I was set on a single tractor propeller high lift configuration (Config. 1, see deliverable D1.1). A second propeller-wing configuration will be investigated in DISPROP’s Phase II (Config. 2, see deliverable D1.1). Furthermore, in coordination with the TM it was decided that Config 1 will be tested in both wind tunnels: at TUB (medium scale) during Phase I and at DNW-NWB (large scale) during Phase II. Config 2, on the other hand, will only be tested at TUB in Phase II. The design of the two medium-scale models is documented in Report D2.1 and the design of the large-scale model will be documented in Report D2.3 at the beginning of Phase II.
During the reporting period the propeller structural design for the large-scale model was completed and documented in deliverable D2.2 a report laying down the methods and results of the design.
The structural design is based on geometric and operational constraints – as selected by the consortium – as well as numerical calculations from IFAS and USTUTT for the loads acting on the propeller.
Based on these prerequisites critical load cases were defined and a preliminary design for the propeller blades and the propeller hub was proposed including a possibility to continuously adjust the pitch of the blades in the hub.
The structural design was substantiated based on the Finite Element Method and dimensioned both with respect to static and fatigue loads. Furthermore, the eigenvalues of the complete setup were determined taking into account the stress stiffening effect in order to assess if eigenvalues might couple with the rotational speed of the propeller setup (Campbell diagram).
Two wind tunnel tests were performed for the first configuration and the results were used to validate the CFD models. The wind tunnel results are discussed in deliverable D3.1. The CFD calculations in Phase I were divided into three parts: 1. preliminary study, 2. specification, and 3. benchmarking of medium-scale wind tunnel tests. Subphase 1 focused on the design of the wind tunnel model and the variation of the propeller settings as well as the effects of the wind tunnel environment. The initial results of this phase were investigated in higher fidelity CFD studies in subphase 2, including further parametric studies. A summary of the CFD work performed in Phase I can be found in deliverable D4.1.
