Airfoil Optimization for a ”Drag Power Kite” and Design Verification By

Master thesis Airfoil Optimization for a ”Drag Power Kite” and Design Veriﬁcation by Wind Tunnel Testing

Contact/Applications to: Florian Bauer,∗ ﬂ[email protected] and Filippo Campagnolo,† ﬁ[email protected]

Announcement date: March 16, 2020

Motivation

Power generating kites have the potential to generate clean energy at a low cost competitive with coal power plants or cheaper without subsidies (see e.g. [1, 2, 3] and references therein). “Drag power” kites generate power with onboard wind turbines and generators by ﬂying fast crosswind motions, see Fig. 1. Electrical power is transmitted to the ground at a medium voltage level via electric cables in the tether.

Figure 1: 20 kW “drag power” kite visualization of kiteKRAFT (image source: http://kitekraf t.de/Images/20kWProduct.png, accessed: Aug 11, 2019).

∗Institute for Electrical Drive Systems and Power Electronics, Department of Electrical and Computer Engi- neering, Technical University of Munich †Chair of Wind Energy, Department of Mechanical Engineering, Technical University of Munich

1 Tasks, Suggested Solution Approach, Expected Results

In this student work, the multi-element airfoil of such a “drag power” kite shall be optimized with MSES, a CFD Software written at the MIT which can be used for high lift multi-element airfoils. The global optimum can be identified by the genetic algorithm CMA-ES. Based on previous student works, the framework of the optimization (coupling of MSES with CMA-ES in MATLAB), including the geometric parametrization and convergence improvements, is given. Based on this setup further improvements of the framework with focus on 2-element airfoils shall be performed. Once a first iteration is finalized, wind tunnel tests shall be prepared. Therefore the obtained optimized 2-element airfoil shall be printed in sections with the Formlabs Form 3 printer (Fig. 2). The student shall prepare and perform wind tunnel tests, including the detailed coordination with the aerodynamic chair and the design and manufacture of the wind tunnel test rig.

Figure 2: Formlabs Form 3 LFS Printer (image source: https://formlabs.com/3d-printers/form -3/, accessed: March 16, 2020).

Starting Point

This announcement, the literature list below, and additionally provided internal documents upon start.

Report and Presentation Guidelines

One report (or thesis) and at least one presentation of the results are required. Guidelines and templates can be downloaded from https://github.com/floba/StudentGuidelines.

Your Proﬁle

This student work will be jointly supervised by the Institute for Electrical Drive Systems and Power Electronics, the Chair of Wind Energy and the TUM startup kiteKRAFT. The ideal candidate

2 • is a student in mechanical engineering, aeronautics, mechatronics or related ﬁelds, • has experience/knowledge in CFD simulations, • has prototyping experience,

• has good skills/background knowledge in aerodynamics, MATLAB, Oﬃce, LaTeX, • is motivated in the respective ﬁeld of science and engineering, • has good English and German language skills.

References

[1] M. Loyd, “Crosswind kite power,” Journal of Energy, vol. 4, no. 3, pp. 106–111, 1980. [2] U. Ahrens, M. Diehl, and R. Schmehl, Eds., Airborne Wind Energy, ser. Green Energy and Technology. Springer Berlin Heidelberg, 2013.

[3] kiteKRAFT: Website, https://www.kitekraft.de, accessed: Aug 11, 2019. [4] A. M. O. Smith. High-lift aerodynamics. Journal of Aircraft, 12(6):501530, 2016/11/25 1975. [5] Florian Bauer, Ralph M. Kennel, Christoph M. Hackl, Filippo Campagnolo, Michael Patt, Roland Schmehl, Drag power kite with very high lift coeﬃcient, Renewable Energy, Volume 118, 2018, Pages 290-305, ISSN 0960-1481, https://doi.org/10.1016/j.renene.2017.10.073. (ht tp://www.sciencedirect.com/science/article/pii/S0960148117310285)