Aerofoil trailing-edge noise prediction models for wind turbine applications

This paper proposes a modified TNO model for the prediction of aerofoil trailing-edge noise for wind turbine applications. The capabilities of the current modified model and four variants of the TNO model are analysed through a comprehensive study which includes 10 aerofoils and involves two different wind tunnels. The Reynolds numbers considered are between 1.13 and 3.41 million, and the effective angles of attack are between −2.20° and 13.58°. The merit of a model is assessed by comparing two aspects of the numerically predicted and the experimentally measured sound pressure level spectra: the sound pressure level difference between two different aerofoils at similar lift coefficients within a certain frequency range (referred to as the delta noise); and the closeness in terms of spectral magnitude and shape of the predicted and measured sound pressure level spectra. The current modified model is developed by deriving new formulations for the computation of the wall pressure fluctuation spectrum. This is achieved by using the approximate ratio of the normal Reynolds stress components for an anisotropic flow over a flat plate to estimate the vertical Reynolds stress component, and by introducing new stretching factors to take the effects of turbulent flow anisotropy into account. Compared with the four TNO model variants tested, the current modified model has strong delta noise prediction ability, and is able to predict sound pressure level spectra that are more consistent and closer to measurements for the vast majority of aerofoils and flow conditions tested in the two wind tunnels

Benjamin’s ‘flâneur’ and serial murder: An ultra-realist literary case study of Levi Bellfield

This article seeks to develop criminological theory with the application of a literary device known as the ‘flâneur’ – an individual described as a ‘stroller’ – to serial murderer Levi Bellfield. With this application of the ‘flâneur’ to the phenomenon of serial murder, this article provides a fresh theoretical ‘lens’, and specifically sheds light on how particular serial murderers operate and evade detection in modern society. The importance of modernity to the phenomenon of serial murder is also considered utilizing Ultra-Realist theory, resulting in both a micro and macro examination into how the modern urban landscape has subsequently created an environment in which the serial killer both operates and comes to fruition. This synthesis between the application of literary devices, criminological theory and socio-cultural concepts not only raises important and previously neglected questions pertaining to serial murder, but also assists in forming the more sinister relative of the flâneur: the ‘dark flâneur’

A study on the prediction of aerofoil trailing-edge noise for wind-turbine applications

This paper presents a comparative study between the so-called BPM and TNO models for the prediction of aerofoil trailing-edge noise with particular emphasis on wind-turbine applications (the BPM model is named after Brooks, Pope and Marcolini who first proposed the model, and the TNO model is named after the TNO institute of Applied Physics where it was first proposed). In this work, two enhanced versions of the BPM model are proposed, and their performances are compared against two recent anisotropic TNO models that require more detailed boundary-layer information than the BPM-based models. The two current enhanced models are denoted as BPMM-PVII and BPMM-BLk?, where the former uses a panel method with viscous-inviscid interaction implemented (PVII) for boundary-layer calculations, the latter estimates the boundary-layer (BL) properties using a two-dimensional k-? turbulence model (k?), and BPMM stands for BPM-Modified. By comparing the predicted sound spectra with existing measurement data for seven different aerofoils tested in the current study, it is shown that the BPMM-PVII model exhibits superior results to those by the other models for most cases despite the simplicity without considering anisotropy. The BPMM-PVII model is then combined with Prandtl's nonlinear lifting-line theory to calculate and investigate three-dimensional rotor noise characteristics of an NREL UAE Phase-VI wind turbine (NREL UAE stand for the National Renewable Energy Laboratory Unsteady Aerodynamic Experiment). It is demonstrated that the current approach may provide an efficient solution for the prediction of rotor aerodynamics and noise facilitating industrial design and development for low-noise wind turbines

High performance cost-effective large wind turbine blades using air-jet vortex generators

Contractor: Aerolaminates Ltd.SIGLEAvailable from British Library Document Supply Centre-DSC:3816.4795(41/00541) / BLDSC - British Library Document Supply CentreGBUnited Kingdo