GALCIT Colloquium

Using wind turbines in urban areas supports an increasing demand for energy that comes with rapid population growth in a sustainable way. The challenge that has been largely neglected, however, is that urban environments are characterized by relatively low wind speeds, large velocity gradients, and significant wind fluctuations, all of which degrades wind farm efficiency. Hess Tower, built in 2010, is a 29-story office building situated in the heart of downtown Houston, TX. Unique to the building is a roof structure that was engineered to house ten vertical-axis wind turbines (VAWTs). Despite detailed wind tunnel measurements to predict the flow conditions on the roof before the building was constructed, the Hess VAWTs were removed soon after construction when one of the turbines failed and fell to the ground. In this talk, I will present new in-situ measurements taken on the roof of Hess Tower and compare this with the pre-construction wind tunnel data to assess the accuracy of the predicted flow field. I will also present results from recent wind tunnel experiments conducted in our lab to examine the effects of VAWT blade curvature on turbine performance and wake development. We find that a simple change in the helical twist of the blades plays a significant role in the VAWT aerodynamics, which has implications for both for small-scale urban VAWT use and large-scale arrays.