Session: 41-04 Offshore wind

Submission Number: 176740

Blade Number Effects on Optimized H-Shaped VAWT at Tilted Operation: A CFD Study 

This study presents a detailed numerical investigation of the performance of an optimized H-shaped vertical axis wind turbine (VAWT), previously introduced at the ASME Turbo Expo (2024 and 2025), with a particular focus on the effect of blade number on aerodynamic efficiency. The motivation is to evaluate whether reducing the number of blades, and thereby the material and associated costs, can be achieved without compromising energy harvesting performance. Under identical operating conditions, two comparative scenarios are examined: in the first, the same blade chord is maintained, leading to a lower solidity for the two-blade configuration; in the second, the same rotor solidity is preserved, which requires a larger chord for the two-blade case. Unsteady CFD simulations are employed to capture the unsteady aerodynamic behavior and near-wake characteristics of the rotor operating at a 20° tilted angle, representative of typical conditions for floating spar-buoy platforms. The simulations are conducted under both design and high load conditions to ensure that the comparative assessment accounts for a wide range of operating regimes. The analysis reveals how the number of blades influences energy harvesting capability, local aerodynamic performance, and wake structure, shedding light on the aerodynamic trade-offs involved in turbine downsizing.
The findings provide valuable insights into the balance between efficiency, material savings, and contribute to the ongoing advancement of optimized Floating-VAWT technology as a promising solution for offshore wind energy exploitation.

Presenting Author: Nicoletta Franchina University of Bergamo

Presenting Author Biography: Nicoletta Franchina is an Associate Professor in Fluid Machinery at the University of Bergamo. She earned both her degree and PhD from the same institution. Her research focuses on turbomachinery, combining experimental and numerical approaches. In the past decade, her work has primarily centered on vertical-axis wind turbines (VAWTs), with in-depth studies of their flow dynamics, wake behavior, performance, and optimization.

Authors:

Otman Kouaissah Norwegian University of Life Sciences
Nicoletta Franchina University of Bergamo
Haris Hameed Mian Norwegian University of Life Sciences
Giacomo Persico Politecnico di Milano
Muhammad Salman Siddiqui Norwegian University of Life Sciences