Channel Geometry Optimization for Vertical Axis Wind Turbines in Skyscrapers

Abstract

Driven by the air pollution and the urbanization of the world, more attention is being paid to sustainable energy technologies such as wind power generation in the built environment. The design of highly efficient vertical axis wind turbines to be deployed in the urban areas is a challenge that, if realized, could revolutionize our energy system. Considering a full integration of the wind turbines during the design phase is a new way of enhancing their power output. A first attempt was performed by Skidmore, Owings & Merrill LLP when building the tunnel-integrated wind turbines of the Pearl River tower in Guangzhou. Basic research proved the benefits of this technique. Yet it has to be optimized. In this thesis, we propose a methodology to assess the performance of fully integrated wind turbines in skyscrapers based on the tunnel’s geometry. We use a cubic Bezier curve to model the opening’s shape. The process is as follows: wind tunnel experiments first, computational fluid dynamics second, followed by design of experiments. We evaluate the wind velocity across the channel. The velocity increase will enhance the power output cubically. We created a reduced scale model 1:150 for the wind tunnel experiments in the wind tunnel. The CFD simulations are run in OpenFoam using steady RANS equations and RNG k-ԑ turbulence model. We assess the wind speed enhancement yield by a shape modification. And, we measure our CFD model accuracy (less than 5% error in critical positions). The obtained results prove the contraction ratio is more significant than its location. In addition, the convexity of the tunnel does not seem to have an impact on the maximum velocity reached at the contraction level. Finally, we model the maximum speed in terms of the geometry factors used in this study and propose the optimal shape.

Date of Award	2014
Original language	English
Awarding Institution	The Hong Kong University of Science and Technology