Study of the dynamic response of a CAARC building by the synthetic wind method and comparison with different approaches

Purpose This paper analyzes the effect that is generated in the dynamic response of a Commonwealth Advisory Aeronautical Council building for different types of power spectra. This article also compares synthetic wind method (SWM) results with wind tunnel tests and other numerical approaches.Design/methodology/approach One of the main methodologies developed in Brazil, the SWM, is employed to determine the dynamic wind loads. The Davenport, Lumley and Panowski, Harris, von Karman and Kaimal model are used in SWM to generate the resonant harmonics. Lateral pressures are calculated by the wind speed deflection profile for 30, 35, 40 and 45 m/s. The structure is processed in Autodesk Robot Structural Analysis with numerical analysis in FEM by the Hilber–Hughes–Taylor method. To corroborate the synthetic wind with experimental results, displacement curves are developed for wind tunnel experimental results, Davenport method, Eurocode and NBR 6123, together with the SWM.Findings Results show that for 30 m/s, the lowest convergence of the power spectra models was presented and that the greatest difference found was below 10%. In addition, it was shown that Eurocode 1-4 can lead to oversizing, while NBR 6123 can lead to undersizing, compared with the experimental results. Finally, results by the Davenport method, wind tunnel test and synthetic wind showed good accuracy.Originality/value By carrying out this comparative analysis, this work presents an important contribution in the field of calculating the dynamic response of tall buildings. Studies with these comparisons to corroborate the SWM had not yet been carried out.

Design, Manufacture and Wind Tunnel Test of a Modular FishBAC Wing with Novel 3D Printed Skins

This paper introduces a new modular Fish Bone Active Camber morphing wing with novel 3D printed skin panels. These skin panels are printed using two different Thermoplastic Polyurethane (TPU) formulations: a soft, high strain formulation for the deformable membrane of the skin, reinforced with a stiffer formulation for the stringers and mounting tabs. Additionally, this is the first FishBAC device designed to be modular in its installation and actuation. Therefore, all components can be removed and replaced for maintenance purposes without having to remove or disassemble other parts. A 1m span, 0.27m chord morphing wing with a 25% chord FishBAC was built and tested mechanically and in a low-speed wind tunnel. Results show that the new design is capable of achieving the same large changes in airfoil lift coefficient (approximate ΔCL≈0.55) with a low drag penalty seen in previous FishBAC work, but with a much simpler, practical and modular design. Additionally, the device shows a change in the pitching moment coefficient of ΔCM≈0.1, which shows the potential that the FishBAC has as a control surface.

Aerodynamic Design and Wind Tunnel Tests of Small-scale Horizontal-axis Wind Turbines for Low Tip Speed Ratio Applications

In recent times, the application of small-scale horizontal axis wind turbines (SHAWTs) has drawn interest in certain areas where the energy demand is minimal. These turbines, operating mostly at low Reynolds number (Re) and low tip speed ratio (λ) applications, can be used as stand-alone systems. The present study aims at the design, development, and testing of a series of SHAWT models. On the basis of aerodynamic characteristics, four SHAWT models viz., M1, M2, M3, and M4 composed of E216, SG6043, NACA63415, and NACA0012 airfoils, respectively have been developed. Initially, the rotors are designed through blade element momentum theory (BEMT), and their power coefficient have been evaluated. Thence, the developed rotors are tested in a low-speed wind tunnel to find their rotational frequency, power and power coefficient at design and off-design conditions. From BEMT analysis, M1 shows a maximum power coefficient (Cpmax) of 0.37 at λ = 2.5. The subsequent wind tunnel tests on M1, M2, M3, and M4 at 9 m/s show the Cpmax values to be 0.34, 0.30, 0.28, and 0.156, respectively. Thus, from the experiments, the M1 rotor is found to be favourable than the other three rotors, and its Cpmax value is found to be about 92% of BEMT prediction. Further, the effect of pitch angle (θp) on Cp of the model rotors is also examined, where M1 is found to produce a satisfactory performance within ±5° from the design pitch angle (θp, design).