Wind-Tunnel Measurement of Differential Pressure on the Surface of a Dynamically Inflatable Wing Cell

Benedetti, Diego Muniz; Veras, Carlos

doi:10.3390/aerospace8020034

Cited by 6 publications

(2 citation statements)

References 42 publications

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“…Ram-air kites and parafoils are made of thin woven fabric and are inflated by the airflow entering the wing through intakes located at the kite's leading edge [9][10][11][12]. The aerodynamic shape of the wing is defined by internal ribs similar to the ribs in an aircraft wing and bridle lines that attach to the ribs and transmit the forces from the wing to the tether [13].…”

Section: Introductionmentioning

confidence: 99%

An Aero-Structural Model for Ram-Air Kite Simulations

Thedens¹,

Schmehl

2023

Energies

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Similar to parafoils, ram-air kites are flexible membrane wings inflated by the apparent wind and supported by a bridle line system. A major challenge in estimating the performance of these wings using a computer model is the strong coupling between the airflow around the wing and the deformation of the membrane structure. In this paper, we introduce a staggered coupling scheme combining a structural finite element solver using a dynamic relaxation technique with a potential flow solver. The developed method proved numerically stable for determining the equilibrium shape of the wing under aerodynamic load and is thus suitable for performance measurement and load estimation. The method was validated with flight data provided by SkySails Power. Measured forces on the tether and steering belt of the robotic kite control pod showed good resemblance with the simulation results. As expected for a potential flow solver, the kite’s glide ratio was overestimated by 10–15%, and the measured tether elevation angle in a neutral flight scenario matched the simulations within 2 degrees. Based on the obtained results, it can be concluded that the proposed aero-structural model can be used for initial designs of ram-air kites with application to airborne wind energy.

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Section: Introductionmentioning

confidence: 99%

An Aero-Structural Model for Ram-Air Kite Simulations

Thedens¹,

Schmehl

2023

Energies

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“…An instrumentation system for in situ measurement of the pressure differential at the upper and lower surfaces of dynamically inflatable wings were designed and tested by Benedetti, Gurgel Veras [ 5 ]. The experimental data confirms the occurrence of a bottom leading-edge recirculation bubble, linked to the low Reynolds regime and the presence of an air intake.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Determination of Strength Characteristics Related to Paraglider Wing with Fourier Transform Infrared Spectroscopy of Applied Materials

et al. 2022

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The aim of paper is to determine experimentally and numerically the strength characteristics related to the paraglider wing with Fourier transform infrared spectroscopy of applied materials. The applied method consists in theoretical modeling supplemented by the tests of material parameters. First, the set of 10 lightweight fabrics was selected for the tests; the samples are representative for these structures. The materials were tested using the spectroscopy to determine the FTIR spectra. The samples differ in the content of certain characteristic groups. Air permeability change of the materials was determined for the different pressure drops. The air permeability of almost all the analyzed samples was close to zero with the exception of only one material. The tensile strength and elongation at the break of samples were determined on the testing machine. The paraglider samples were characterized by slightly decreased mechanical properties compared to the parachute fabrics. The material characteristics determined during the tests are the input data for the theoretical analysis. The numerical model of the paraglider wing is based on a 3D geometry from previous research, but the stress, strain, and deformation were determined using the ANSYS Structural program and the finite elements method. To determine the strength correctly, we introduce two basic values: the absolute maximal and the representative values that are the biggest repetitive values of stress, strain, and deformation. The stress value was determined by the main factors: (i) the thinner the material, the bigger the stresses that were accumulated; (ii) the stronger the material, the bigger the stresses that were accumulated. The results are similar for all materials and differ mainly by the values. The biggest stresses were observed inside the material contacting the ribs, whereas the biggest deformation and strain were in the regions between ribs, and the smallest were in the contact areas with the fixed supports. Their highest intensity was observed on the leading edge of the paraglider. We conclude that the obtained stresses were far from the breaking level for the wing.

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Wind Tunnel Testing of Tethered Inflatable Wings

Desai,

Schetz,

Kapania

et al. 2024

Journal of Aircraft

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A wind tunnel testing approach for tethered inflatable wings is presented. Use cases for such wings range from airborne wind energy systems to high-altitude communication platforms. The tests were conducted for two tethered inflatable wings, one made out of nylon fabric and the other an ultra-high-molecular-weight polyethylene fabric. They were tested within a speed range of 15–32.5 m/s for three tether attachment configurations. Stereo photogrammetry data, force and moment measurements, and wake pressure measurements were recorded for each speed and test configuration. These measurements provide an experimental database for aeroelastic model validation and comparison with high-fidelity computational fluid dynamics studies. The effects of wing fabric material and tether attachment configurations on aerodynamic performance were explored and found to have a profound impact. These tests also highlight the possibility of passive aeroelastic tailoring of the wing configuration to achieve desired aerodynamic performance in the form of high lift and load alleviation. Some testing challenges and possible sources of measurement uncertainty are also discussed.

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Wind-Tunnel Measurement of Differential Pressure on the Surface of a Dynamically Inflatable Wing Cell

Cited by 6 publications

References 42 publications

An Aero-Structural Model for Ram-Air Kite Simulations

An Aero-Structural Model for Ram-Air Kite Simulations

Experimental and Numerical Determination of Strength Characteristics Related to Paraglider Wing with Fourier Transform Infrared Spectroscopy of Applied Materials

Wind Tunnel Testing of Tethered Inflatable Wings

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