Date of Award

Fall 2010

Project Type


Program or Major

Mechanical Engineering

Degree Name

Master of Science

First Advisor

Joe Klewicki


The concept of the Ducted Wind Turbine (DWT) has received significant research interest over the last fifty years. Several attempts to commercialize the DWT have been made in the past, but a commercial version does not exist at present. One of the primary concerns has been the size of the duct of the DWT and the economical and structural challenges relative to its design. It has been observed, both from existing as well as new experimental results at UNH, that significant reductions in the size of the duct can be achieved by better modeling the three dimensional flow in the duct. Specifically, the inherent swirling nature of the turbine wake flow is found to have significant influence on delaying the boundary layer separation in the diffuser, and thereby improving the diffuser performance considerably, concurring with Prasad and Ostrach (1971); McDonald et al. (1971); Senoo et al. (1978); Okhio et al. (1983). This improvement in diffuser performance facilitates a smaller diffuser, and hence a smaller duct. The present work addresses a DWT design optimization study in two parts: (1) a preliminary theoretical analysis showing a potential to reduce the length of the diffuser by up to 40%, and (2) experiments that were carried out on three DWT scale models that were prototyped at UNH to study the influence of swirl on the diffuser pressure recovery. Additionally, results from experiments have also shown scope of power augmentation of more than 40% through the use of a duct, compared to a same-rotor-diameter unducted turbine.