Piezo-actuated Vibration and Flutter Control

The potential application of smart materials is being investigated by various researchers inthe perspective of building intelligent systems. A smart structure consists of distributed actuatorsand sensors with associated processors to analyse and control the structure. Piezoceramics,magnetostrictive materials, electro-rheological fluids, magneto-rheological fluids, shape memoryalloys, fibre optics are quite often used in realising a smart/intelligent system. In this paper,vibration and flutter control using piezoceramics is reviewed. Various aspects covering relativemerits of piezoceramics with other smart materials and application capabilities are discussed

H-Darrieus vertical axis wind turbine aerodynamics and aeroacoustics under different inflow conditions

Abstract: The aerodynamics and aeroacoustics of a scaled model H-Darrieus vertical axis wind turbine (VAWT) with end plates and supporting structures is investigated at its design operational regime. A high-fidelity hybrid Lattice Boltzmann Method/Very Large Eddy Simulation model is achieved and coupled to an in-house aeroacoustic propagation code SherFWH based on the Ffowcs Williams and Hawkings’ analogy for noise prediction. A simulation is first performed under uniform inflow conditions to validate the model with available experimental data. A good agreement is seen between the numerical predictions and the experimental noise spectra for both the tonal peaks at the blade passing frequencies and the broadband noise levels. A second simulation is performed with the VAWT titled by an angle of 20? to study the influence of skewed inflow conditions, which are more representative of a typical urban environment. A 12% decrease in the power coefficient and a 2.3 dB decrease in the overall noise level at a given observer position is seen for the skewed inflow model.Communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Effect of different source terms and inflow direction in atmospheric boundary modeling over the complex terrain site of Perdigão

Assessing wind conditions in complex terrain requires computational fluid dynamics (CFD) simulations incorporating an accurate parameterization of forest canopy effects and Coriolis effects. This study investigates how incorporating source terms such as the presence of trees and the Coriolis force can improve flow predictions. Furthermore, the study examines the impact of using different sets of atmospheric boundary layer inflow profiles, including idealized profiles with a logarithmic velocity profile, and a set of fully developed profiles from a pressure-driven precursor simulation. A three-dimensional steady Reynolds-averaged Navier–Stokes (RANS) equations model is set up using OpenFOAM to simulate the flow over a complex terrain site comprising two parallel ridges near Perdigão, Portugal. A 7.5 km×7.5 km terrain of the Perdigão site is constructed from elevation data centered around a 100 m met-mast located on the southwest ridge. A 30 min averaged stationary period is simulated, which corresponds to near-neutral conditions at met-mast Tower 20 located at the southwest ridge. The period corresponds to the wind coming from southwest at 231∘ at 100 m height above ground at Tower 20. Five case setups are simulated using a combination of different source terms, turbulence models and inflow profiles. The prediction capability of these models is analyzed for different groups of towers on the southwest ridge and, on the towers further downstream inside the valley, on the northeast ridge. Including a canopy model improves predictions close to the ground for most of the towers on the southwest ridge and inside the valley. Large uncertainties are seen in field measurement data inside the valley, which is a recirculation zone, and large prediction errors are seen in the wind velocity, wind direction and turbulent kinetic profiles for most of the models. The predictions on the northeast ridge are dependent on the extent of recirculation predicted inside the valley. The inflow wind direction plays an important role in wind profile predictions.publishedVersio

Phytocapping of municipal landfills: Evaluating the performance of 21 tree species and two soil depths

"Capping is a mandatory landfill closure procedure to isolate the waste from outside environment, mainly rain water. Clay caps are mostly expensive and often fail to limit entry of water into the waste by developing cracks due to desiccation. To reduce capping costs and to increase environmental benefits, an alternate capping system called ‘Phytocapping’ was trialled at Lakes Creek Road Landfill, Rockhampton, Australia. This system consists of a soil cover and vegetation. Soil cover stores water during rainfall events and the vegetation removes the stored water via transpiration. Trees also act as ‘rain interceptors’ by trapping certain proportion of the rainfall in their canopy. Soil and plants also contribute to reduced methane emission by supporting methanotrophs in their root zone.

Phytocapping of municipal landfills: Evaluating the performance of 21 tree species and two soil depths

"Capping is a mandatory landfill closure procedure to isolate the waste from outside environment, mainly rain water. Clay caps are mostly expensive and often fail to limit entry of water into the waste by developing cracks due to desiccation. To reduce capping costs and to increase environmental benefits, an alternate capping system called ‘Phytocapping’ was trialled at Lakes Creek Road Landfill, Rockhampton, Australia. This system consists of a soil cover and vegetation. Soil cover stores water during rainfall events and the vegetation removes the stored water via transpiration. Trees also act as ‘rain interceptors’ by trapping certain proportion of the rainfall in their canopy. Soil and plants also contribute to reduced methane emission by supporting methanotrophs in their root zone.