IFASD2024 Paper Submission & Registration
17 – 21 June 2024, The Hague, The Netherlands

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09:40   Distributed propulsion 1
Chair: Alessandro Scotti
30 mins
Wind tunnel test of gust response for distributed propeller-wing system
Kunhui Huang, Zhitao Zhang, Dawei Liu, Changchuan Xie
Abstract: It is known for us the distributed-propeller aircraft is becoming more popular and important in aerospace industry[1][2], such as NASA’s X-57. As a result, lots of literature concentrated on its steady/unsteady aerodynamic performance[3][4]. However, there has been little research in the sensitivity of gust response to distributed-propeller aircraft. This paper presents a wind tunnel test of the sensitivity of a distributed propeller-wing model to the variations in freestream velocity, rotation speed, and gust frequency. In the wind tunnel test, a six-component balance was mounted at the wing root in order to measure the aerodynamic loads. A more advanced Fiber Optic Sensing System (FOSS)[5] was also designed and deployed in the wing spar to measure the wing deformation response affected by gust. In addition to this, a gust generator was installed upstream in the wind tunnel which consists of two symmetric oscillating wings driven by a linear motor to generate alterable amplitude and frequency continuous sin gust. In these gust response experiments (the wing was fixed vertically under a 2° angle of attack, 19 m/s freestream velocity, 8000 r/min rotation speed and the gust generator oscillated with a frequency of 2 Hz producing continuous sin gust), the effect of distributed-propeller is quite obvious. The value of bending moment measured by the six-component balance is increased by 16.84% compared to a clean wing without propeller influence. Similarly, due to the presence of distributed-propeller, the vertical deformation response centre of the wing-tip increased from 30 mm to 42 mm, an astonishing 40% improvement. There is no doubt that the oscillating amplitude of the wing-tip is increased in the vertical and horizontal directions. When the gust frequency is near the vertical mode frequency, the vertical deformation increases fast and reaches to an extremum. According to the quantitative results of the above tests, the distributed-propeller effect does have a significant influence on the load characteristics and elastic deformation response of the wing. Next, we will analyse and study the results obtained from the wind tunnel experiment in more detail in order to share a more mature and interesting presentation at the IFASD2024 conference.
30 mins
The Effect of Aerodynamic Interactions on Aeroelastic Stability in Wing-Propeller Systems
Nils Böhnisch, Carsten Braun, Vincenzo Muscarello, Pier Marzocca
Abstract: This paper presents initial findings from aeroelastic studies conducted on a wing-propeller model, aimed at evaluating the impact of aerodynamic interactions on wing flutter mechanisms and overall aeroelastic performance. Utilizing a frequency domain method, the flutter onset within a specified flight speed range is assessed. Mid-fidelity tools with a time domain approach are then used to account for the complex aerodynamic interaction between the propeller and the wing. Specifically, open-source software DUST and MBDyn are leveraged for this purpose. This investigation covers both windmilling and thrusting conditions of the wing-propeller model. During the trim process, adjustments to the collective pitch of the blades are made to ensure consistency across operational points. Time histories are then analyzed to pinpoint flutter onset, and corresponding frequencies and damping ratios are meticulously identified. The results reveal a marginal destabilizing effect of aerodynamic interaction on flutter speed, approximately 5%. Notably, the thrusting condition demonstrates a greater destabilizing influence compared to windmilling. These comprehensive findings enhance the understanding of the aerodynamic behavior of such systems and offer valuable insights for early design predictions and the development of streamlined models for future endeavors.

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