The 50 m2kite which is installed on the žEnergy Observerž yacht, in the launching phase (23 June 2017)
Richard Leloup
Kite Design Engineer Beyond the sea⃝R 1010 avenue de l’Europe
33260 La Teste Du Buch France
richard.leloup@ensta-bretagne.org www.beyond-the-sea.com
Kite Profile Optimization using Reynolds-Averaged-Navier-Stokes
Flow Simulations
Richard Leloup, Tanguy Raffray
Beyond the sea⃝R
In the kitesurfing industry, empirical methods are used to design the kites due to the absence of any alternative, es-pecially numerical methods. Nevertheless, the kites ded-icated to auxiliary propulsion of ships developed by the Beyond the sea⃝R project are bigger, more complex and more expensive. Thus, the 3D Lifting Line method was developed to calculate the local and global aerodynamic forces and thereby the aerodynamic performances of a kite [1]. This method was then integrated into a Fluid-Structure Interaction loop in order to evaluate the defor-mation and stress in the canopy, in the inflatable tube structure and in the lines [1]. Up to now, the potential flow solver XFOIL was used to evaluate the 2D profile aero-dynamic characteristics, which are given as an input to the 3D Lifting Line method. In this study, the RANS CFD software OpenFOAM was used in order to improve the ac-curacy of 2D profile aerodynamic calculations despite a computation time increase by 20 times.
The objective of this study is to compare several kite profiles by varying two different parameters: Maximum Thickness (MT) of the profile and Maximum Thickness Po-sition (MTP). The comparison was performed as follow: first, the intervals of maximum thickness position and maximum thickness were adjusted. Then, a study of the variation of the two parameters MTP and MT was carried out on the previously defined intervals. It was thus pos-sible to plot a surface as shown in figure 1 and then to determine the best profiles in terms of aerodynamic per-formances (better lift coefficient, better fineness, greater stall angle, etc.). This allowed us to determine the best
profile for static flight and for dynamic flight. The inte-gration of the calculations on a 2D profile in the 3D Lift-ing Line method will make possible to evaluate the aero-dynamic performances of a given kite 3D geometry and thus to compare many geometries. Therefore, the manu-facture of many prototypes during the design process of a kite will be drastically limited.
2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 Position of Maximum
Thickness (%) Maximum Thickness (%)
Maximum Li
�
Coe
ff
icient (-)
Maximum lift coefficient (CLMAX) as a function of Maximum Thick-ness (MT) and Maximum ThickThick-ness Position (MTP).
References:
[1] Leloup R.: "Modelling approach and numerical tool develop-ments for kite performance assessment and mechanical design; application to vessels auxiliary propulsion". PhD Thesis, European University of Brittany, 2014.
